HK1260061B

HK1260061B - Conductive composites

Info

Publication number: HK1260061B
Application number: HK19119789.6A
Authority: HK
Inventors: 黄昌仪; 诺布由熙·乔·梅吉; Q·宋
Original assignee: 安泰奥能源科技有限公司
Priority date: 2016-03-29
Filing date: 2017-03-29
Publication date: 2022-12-23

Description

Electrically conductive composite material

Technical Field

The present invention relates to the field of composite material formulations and composite articles formed therefrom. In particular, the present invention relates to forming electrically conductive continuous structures, methods of making the same, and their use for making, maintaining, and controlling electrically conductive interfaces.

Background

The reference to any prior art in the specification is not an acknowledgement or suggestion that prior art forms part of the common general knowledge in any jurisdiction or that prior art could reasonably be expected to be understood, regarded as relevant, and/or combined with other prior art by a person skilled in the art.

The flow of electrons and/or ions between different materials is the basis of any energy storage and conversion system. In order to meet the needs for higher capacity and power density and to provide other benefits, including longer cycle life, it is deemed necessary to develop new anode and cathode materials. New material compositions and doping methods, different microstructures/shapes and nanostructures/shapes, and the use of surface coatings are all active areas of research, and it is desirable to provide improved performance of the active materials used in such energy storage and conversion systems. However, this is not the only issue to consider when producing, for example, higher performance batteries. The stack functions due to the flow of electrons and ions across the interfaces formed by the different materials, so at each interface it is critical to promote this flow and maintain good conductivity. Maintaining this functionally effective interface between current collectors, such as aluminum (cathode) and copper (anode), and their respective active material coatings is critical to performance and improved operating life.

Similarly, maintaining a functionally effective interface between the different components that make up the active material coating is also critical to performance and improved operating life. An interface occurs when two "phases" form a boundary, and the way in which the two phases mix together will depend on their surface chemistry and the extent to which the interface is present per unit volume. In the case of nanoparticles and microparticles, particle size and distribution, shape and morphology, as well as overall surface area and porosity, are the core determinants of mixing. In addition, the surface chemistry of the particles, including the presence or absence of surface charge, density and distribution, and the overall hydrophobic to hydrophilic balance, are another set of core parameters. These factors together determine the extent to which different particles will form a uniformly dispersed or poorly dispersed system. Therefore, forming a homogeneous mixture of different nano-and micron-sized particles in different solvents (organic as well as aqueous) is far from a trivial process.

With smaller particles, the surface area/volume ratio is increased, making surface properties critical, which affects interfacial properties and aggregation behavior. Where two or more different particles having uniquely different surface properties are involved, forming a uniform composite is very challenging. Breaking up the aggregated similar particles and maximizing homogeneity requires high shear forces, which in turn further complicates the process and increases the cost of reproducing composite formulations that produce desirable properties.

In the field of nanocomposites or multiphase materials that can provide unique or otherwise difficult to obtain properties, it is critical to obtain good uniformity between or within composite particles, ribbons, tubes, plates and other structural components. One example of such a composite material is found in the development of electronic materials for batteries or capacitors and supercapacitors, as well as other energy storage and conversion systems. Next generation anodes require materials comprising a mixture of silicon and carbon nanoparticles with a binder (such as polyacrylic acid) in a predetermined ratio. Different silicon materials are being developed, such as alloys, core-shell structures, porous structures and nanostructures, each having different surface chemistries. In addition, different carbon materials in the form of graphite, super-P carbon, graphene, carbon nanotubes, carbon nanofibers, acetylene black, and Ketjen Black (KB) may be incorporated into certain composite materials as desired. All of these materials can ultimately exhibit a wide range of hydrophobic and hydrophilic characteristics, and there is conventionally no simple method of reliably and predictably producing homogeneous mixtures from these various materials. One example of such a material is in the field of conductive nanocomposites that are commonly used for various industrial applications. The conductive composite material can be used for electro-optical equipment, electrostatic discharge, conductive paint, lightning stroke protection and the like. The present invention addresses at least some of the deficiencies of the prior art described above.

Disclosure of Invention

The present invention is based, at least in part, on the discovery that particles of different surfaces, charges, sizes, hydrophobicity, and other characteristics can be advantageously mixed in the presence of certain metal coordination complexes to form more reliable homogeneous composite precursor formulations that yield improved characteristics in subsequently formed composites. One such key application is the presence of metal coordination complexes in the conductive composite active material interface, which has many benefits over the use of uncoated active materials, current collectors, or other material interfaces. The use of metal coordination complexes as adhesives or coatings at the conductive interface formed by such composites provides improved adhesion layers (from a strength and stability perspective) and provides a more effective conductive interface. Without wishing to be bound by theory, the inventors believe that the metal coordination complexes may serve to minimize aggregation of nano-sized and micro-sized active materials, thereby improving dispersion and interaction in mixtures comprising different active materials having different surface properties, and thus forming more dispersed and well-distributed composite precursor formulations and composites formed therefrom.

In a first aspect, although not necessarily the broadest aspect, the invention relates to a composite precursor formulation comprising: (i) a first active material; (ii) a second active material; and (iii) a metal coordination complex, wherein the first active material and the second active material have at least one surface property different from each other.

In one embodiment, the composite precursor formulation may further comprise a liquid carrier.

The liquid carrier can be an aqueous or organic solvent, or a mixture thereof, or the liquid carrier can be an additional liquid active material.

In a second aspect, the present invention relates to a method of producing a composite material precursor formulation comprising the steps of: (i) providing a first active material and a second active material, wherein the first active material and the second active material have at least one surface property that is different from each other; (ii) providing a metal coordination complex; and (iii) combining the first and second active materials and the metal coordination complex to form a composite precursor formulation.

In one embodiment, the method may further comprise the step of agitating the mixture of the combination of the first and second active materials and the metal coordination complex.

In a third aspect, the present invention relates to a composite material comprising: (i) a first active material; (ii) a second active material; and (iii) a metal coordination complex bonded or otherwise associated with the first active material and the second active material, wherein the first active material and the second active material, prior to forming the composite, have at least one surface property that is different from one another.

In one embodiment of the above aspect, the metal coordination complex is bound to the first active material and the second active material via an intermediary agent, such as, for example, an adhesive.

In some embodiments, where the composite precursor formulation includes a liquid carrier, then the method may further include the step of removing the liquid carrier.

In a fourth aspect, the present invention relates to a method of forming a conductive interface between two or more active materials, or between at least one active material and a substrate, comprising the steps of: (i) contacting at least one active material and/or substrate with a metal coordination complex; and (ii) mixing the active material or mixing the substrate with at least one active material, or coating the substrate with at least one active material, thereby forming a conductive interface, and wherein at least two active materials or one active material and the substrate have at least one surface property different from each other.

The conductive interface may be formed at least in part from the composite precursor formulation of the first aspect or the composite of the third aspect.

In a fifth aspect, the present invention relates to a conductive interface comprising (i) an active material composite comprising at least two active materials and a metal coordination complex in contact with the active materials; or (ii) an active material mixed with or coated on a substrate and a metal coordination complex in contact with the active material and/or the substrate.

In any embodiment of the fourth and fifth aspects, the electrically conductive interface is an electrically conductive interface through which the flow of electrons and/or ions is provided.

In one embodiment of the fourth and fifth aspects, the conductive interface is part of an electrode or a semiconductor.

At least two active materials, prior to forming the conductive interface, have at least one surface property that is different from each other.

In one embodiment, the substrate may be a spacer.

Preferably, the conductive interface of the fifth aspect is formed by the method of the fourth aspect.

In a sixth aspect, the present invention relates to a method of preparing an electrode comprising a conductive interface, the method comprising the steps of: (i) providing an electrode substrate and an active material; (ii) contacting one or both of the electrode substrate and the active material with a metal coordination complex; and (iii) coating the electrode substrate with an active material, thereby forming an electrode.

The electrically conductive interface of the electrode may be formed at least in part from the composite precursor formulation of the first aspect or the composite of the third aspect or the method of the fourth aspect.

The various features and embodiments of the invention mentioned in the various sections above apply mutatis mutandis to the other sections, so that features indicated in one section may be combined with features indicated in other sections as appropriate.

Further features and advantages of the present invention will become apparent from the detailed description that follows.

Drawings

Fig. 1 is a set of contact angle (θ) measurements performed on a copper current collector as follows, a. control 1 (treated with water instead of a metal coordination complex), b. treated with a metal coordination complex at pH 4.5, c. treated with a metal coordination complex at pH 5.0, d. control 2 (treated with water instead of a metal coordination complex and polyacrylic acid (PAA)), e. treated with a metal coordination complex and PAA at pH 4.5, f. treated with a metal coordination complex and PAA at pH 5.0;

fig. 2 is a set of contact angle (θ) measurements performed on an aluminum current collector as follows, a. control 1 (treated with water instead of a metal coordination complex), b. treated with a metal coordination complex at pH 4.5, c. treated with a metal coordination complex at pH 5.0, d. control 2 (treated with water instead of a metal coordination complex and polyacrylic acid (PAA)), e. treated with a metal coordination complex and PAA at pH 4.5, f. treated with a metal coordination complex and PAA at pH 5.0;

FIGS. 3a-d are a series of SEM images of silicon (1-3 μm) and carbon particle composite precursor formulations with metal coordination complexes (a) COMPO x100, (c) COMPO x250 magnification, and silicon (1-3 μm) and carbon particle composite precursor formulations without metal coordination complexes (b) COMPO x100, (d) COMPO x250 magnification;

FIGS. 4a-d are a series of SEM images of high capacity LiNiCoMnO₂And carbon composite precursor formulations with metal coordination complexes (a) COMPO x100, (c) COMPO x250 amplification, and high capacity LiNiCoMnO₂And a carbon composite precursor formulation without a metal coordination complex, (b) COMPO x100, (d) COMPO x250 amplification;

fig. 5 shows zeta potential data for silicon nanoparticles treated with a metal coordination complex formulation at pH 3.7. At this pH, the metal coordination complex does not form a stable coating and results in partially coated particles having poor coordination potential after rinsing;

fig. 6 shows zeta potential data for silicon nanoparticles treated with a metal coordination complex formulation at pH 5.0. The Si particles have a negative zeta potential, as would be expected from the presence of negatively charged Si-OH groups. Metal coordination complexes that are positively charged and effectively coat negatively charged particles can form net positively charged particles. The metal coordination complex adjusted to pH 5.0 results in more stable positively charged Si nanoparticles, with a larger potential to coordinate with other particles or binders;

FIGS. 7a-d are a series of SEM images of silicon (100nm) and carbon composite precursor formulations with metal coordination complex (a) SEI x1000, (c) COMPO x250 magnification, and silicon (100nm) and carbon composite precursor formulations without metal coordination complex (b) SEI x1000, (d) COMPO x250 magnification;

FIGS. 8a-d are a series of SEM images showing the difference in surface morphology and electrode structure of Si (100nm) electrode samples with (c and d) and without (a and b) metal-coordination complexes (samples have not undergone charge/discharge cycling);

FIGS. 9a-d are a series of SEM images showing the difference in surface morphology and electrode structure after hundreds of deep charge/discharge cycles for Si (100nm) electrode samples with (c and d) and without (a and b) metal-coordination complexes;

fig. 10(a) and (b) are cross-sectional SEM images of (a) the copper foil and active material interface without metal coordination complex formation and (b) the copper foil and active material interface formed in a similar manner but including metal coordination complex formation, taken from a disassembled half of the coin cell after 1000 deep charge and discharge cycles at 0.5C (1C ═ 4,200 mAh/g);

fig. 11(a) and (b) are photographs of (a) a disassembled electrode without metal coordination complex formation and (b) a disassembled electrode formed in a similar manner but including metal coordination complex formation taken from those components of a disassembled half coin cell after 1000 deep charge and discharge cycles at 0.5C (1C ═ 4,200 mAh/g);

Fig. 12(a), (b), (C), and (d) are (a) a 100x, SEI-mode SEM image of a disassembled electrode with metal coordination complex formation, (C) a 250x, SEI-mode SEM image of a disassembled electrode with metal coordination complex formation, and (b) a 100x, SEI-mode SEM image of a disassembled electrode formed in a similar manner but without metal coordination complex formation, (d) a 250x, SEI-mode SEM image of a disassembled electrode formed in a similar manner but without metal coordination complex formation, taken from the disassembled electrode of a half coin cell after 1000 deep charge and discharge cycles at 0.5C, 1C 4,200 mAh/g. The image of the sample with the metal coordination complex shows a hairlike structure corresponding to a battery separator made from fibers of polypropylene/polyethylene. In contrast, when no metal coordination complex was used, almost no separator fibers were observed;

fig. 13(a) and (b) LiNiCoMnO with metal coordination complex from disassembled half coin cells after 1000 deep charge and discharge cycles (at 0.5C, 1C ═ 150mAh/g)₂Photographs of material (a) and control sample (b); and

FIGS. 14(a) and (b) shows LiNiCoMnO of a detached electrode formed (a) with a metal coordination complex and (b) without a metal coordination complex ₂SEM image of material in 100x SEI mode.

Further aspects and further embodiments of aspects of the invention described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

Detailed Description

In a first aspect, the present invention relates to a composite precursor formulation comprising: (i) a first active material; (ii) a second active material; and (iii) a metal coordination complex, wherein the first active material and the second active material have at least one surface property different from each other.

The term composite or nanocomposite is intended to include any mixture of metals, intermetallics, metalloids, carbon, ceramics and/or polymeric materials. When initially mixed to form a uniformly dispersed suspension, slurry or blend, a dry or liquid-based mixture is referred to herein as a composite precursor formulation prior to forming the final composite article or material. When these formulations are converted into the final article or material, they are referred to herein as a composite or article formed using such a composite or a conductive interface.

The term "active material" as used herein may mean, but does not necessarily mean, an active functional effect on electrical conductivity in the final composite and/or conductive interface comprising the same. Additionally or alternatively, the active material may contribute to the strength, elasticity or dispensing characteristics of the composite material. Alternatively, the active effect of the active material may be solely in the composite precursor formulation prior to forming the composite. Preferably, at least one active material will contribute significantly to electrical conductivity. In one non-limiting embodiment, the active material may be a material such as silicon and/or graphite, or other carbon particles that are a component of the conductive interface (such as an electrode). Thus, in one embodiment, the active material (first, second or other) may be a particulate.

The term homogeneous is generally intended to describe a well-dispersed and well-distributed first active material and second active material that form a composite precursor formulation.

The term "conductive interface" is intended to include any arrangement of active materials (first and/or second) and/or substrates in which one material is in close proximity to another material. In some embodiments, the interface presents one continuous material immediately adjacent to another material, which may be continuous or discontinuous. The active material or substrate may be a continuous or discontinuous material. In certain embodiments, the electrically conductive interface will be an electrically conductive interface that allows or facilitates the flow of ions and/or electrons. One non-limiting example of such a conductive interface is an interface between an active material such as silicon, carbon, a binder, or a mixed metal oxide, or an interface between such an active material and an underlying current collector (such as copper or aluminum) on which they are coated. Another embodiment is to form a semiconducting interface between the semiconductor material and a suitable substrate.

In one embodiment, the first active material and the second active material are different from each other in that at least one surface property of one active material is substantially different from the same surface property of the other active material. Surface properties that may differ between active materials may be present in the form of overall surface charge, density and distribution as well as size and distribution, hydrophobicity/hydrophilicity, zeta potential, etc., such that the first and second active materials do not readily disperse with respect to each other. One non-limiting example is where the surface properties of one active material create a distinct or substantially hydrophobic surface, while the other presents a distinct or substantially hydrophilic surface.

In one embodiment, the first active material and/or the second active material of the composite precursor formulation is selected from the group consisting of: metals, metal oxides, ceramics, intermetallics, metalloids, clays, carbon, and both synthetic polymers and biological polymers. In certain embodiments, silicon is a preferred metalloid.

In one non-limiting embodiment, wherein the composite formed from the composite precursor formulation forms part of an electrode, or other conductive interface, and in particular an anode, the first active material and/or the second active material is selected from one or more of silicon, tin, and carbon. The silicon may be pure silicon, its various oxides (SiO )₂Etc.), alloys thereof (Si-Al, Si-Sn, etc.), and composite materials (Si-C, Si-graphene, etc.). Similarly, the tin can also be in any one or more of its various suitable forms. Preferably, the carbon is in the form of one or more carbon particles selected from the group consisting ofFormula (II): one or more of graphite, super-P carbon, graphene, carbon nanotubes, carbon nanofibers, acetylene black, and Ketjen Black (KB). Preferably, the carbon is in the form of graphite.

Preferably, when the electrode is a cathode, the first active material and/or the second active material is selected from one or more of the following: sulfur, LiFePO ₄(LFP), mixed metal oxides containing cobalt, lithium, nickel, iron and/or manganese, and carbon. Preferably, the carbon is in the form of one or more carbon particles selected from the group consisting of: one or more of graphite, super-P carbon, graphene, carbon nanotubes, carbon nanofibers, acetylene black, and Ketjen Black (KB). Preferably, the carbon is in the form of graphite.

The composite precursor formulation may include one or more additional active materials as needed to form the composite, and each of its additional active materials may be selected from the same groups and materials described for the first active material and the second active material. For example, the composite precursor formulation can further include a third active material, a fourth active material, a fifth active material, and the like.

The first and second active materials, and any additional active materials, may be in any shape including: particles, tubes, wires, nanocages, nanocomposites, nanofabrics, nanofibers, nanosheets, nanoflowers, nanofoam, nanonets, boxes, nanoparticles, nanopillars, nanoneedle-hole films, plate-like nanoparticles, nanobelts, nanorings, nanorods, nanoplates, nanoshells, nanopipettes, quantum dots, quantum heterostructures, and engraved thin films. Regardless of the shape or morphology of the first and second, or additional, active materials, at least two of which will have at least one surface property that is different from one another, such that each tends to reverse aggregate upon itself, typically and especially in the absence of a metal coordination complex, to form a homogeneous composite.

In one embodiment, the additional active material may be selected from polar or non-polar polymers.

Such polar and non-polar polymers may be mixed in an aqueous or organic solvent environment. It will be appreciated that with these polymers, if the molecular weight increase is above a threshold, the polymer will be a solid, and in such an embodiment, the composite precursor formulation may be a dry mixture, i.e. may be free of a liquid carrier.

It will be appreciated, therefore, that the first and second active materials, and any additional active materials, can be mixed in a dry mixed environment, a fluid environment, an aqueous solvent environment, and an organic solvent environment, or mixtures thereof, in the presence of the metal coordination complex.

In one embodiment, a dry mixing environment may occur when the high molecular weight polymer is present as one of the first or second active materials or additional components of the formulation. Alternatively, as one of the first or second active materials may contact the metal coordination complex in a liquid environment and this is subsequently dried, mixing in a dry mixing environment may occur. The first or second active material coated with the metal coordination complex can then be dry mixed with the uncoated first or second active material. Thus, although the metal coordination complex itself should be applied in the liquid environment provided by the liquid carrier, the first active material and the second active material may be dry mixed in the presence of the metal coordination complex that has previously been coated on one or both of those active materials in the liquid environment. Such methods are considered to be within the scope of the claims.

In one embodiment, a fluid environment may occur when the heated liquid polymer is present as the first or second active material of the formulation or another material. Alternatively, in one embodiment, a fluid environment may be present by including a liquid carrier in the formulation. When the liquid polymer is one of the first or second active materials, then the other active material will exhibit at least one surface property that is different from the liquid polymer and will readily aggregate therein without the addition of a metal coordination complex.

In this regard, the role of the metal coordination complex in forming the composite precursor formulation and the composites formed therefrom can be viewed as a mixing enhancer, which improves the homogeneity of the mixture or slurry and, in addition, can improve the desired characteristics of the equipment that requires the use of the composite or nanocomposite formed therefrom. In particular, a conductive composite or nanocomposite. Examples of such composite materials are mixtures of active materials used in conductive interfaces, such as mixtures of active materials used in electrodes (e.g. batteries) and supercapacitors. A uniform slurry, for example, comprising silicon and carbon particles, with other active materials (such as one or more binders) is needed to produce the composite materials necessary to improve the performance of the anode, including higher energy density, faster charge and discharge cycles, and to provide longer operating cycle life. Obviously, poor slurry uniformity will result in poor active composite materials and/or poor conductive interfaces and, thus, less than optimal performance for this type of anode and, therefore, reduced overall performance of the battery.

In one embodiment, a layer of metal coordination complex bound to the surface of the first active material and/or second active material particles serves to minimize aggregation and/or agglomeration between particles and facilitates uniformity in formulation. Bridging between different active materials in a composite or nanocomposite can result from metal coordination complexes that are bound to or directly bound to different particles, or indirectly bound to different particles through interactions between the metal coordination complexes and further components of the formulation (such as a bulky matrix).

In this regard, bridging interactions may occur between the active material particles and the bulky matrix via the metal coordination complex. In one embodiment, the matrix may be a metal, ceramic, or polymer present as a continuous phase in which the first and second active material particles or fillers are embedded. Such a matrix may have a single component that may be referred to herein as a vehicle. In certain embodiments, such a matrix and vehicle may be a binder. Thus, in certain embodiments, the metal coordination complex that binds or binds the first or second active material also includes a coordinate bond with an intermediary agent, such as an adhesive moiety. Preferred binder moieties may be selected from the group consisting of carbenes, nitrogen-containing groups, oxygen-containing groups, and sulfur-containing groups. More preferably, the binder moiety is an oxygen-containing group. Most preferably, the binder moiety is selected from at least one of carboxyl, hydroxyl and carbonyl groups. The metal coordination complex may be present at the surface to form a coordinate bond with any adjacent particle, filler, matrix or binder material and the first or second active material and to bridge any one such material with any one or more other materials.

In one embodiment, when included, the binder can be a polymer. In embodiments where it is desired to form a dative bond between the metal coordination complex and the binder, preferred polymers are those that include oxygen species (oxyden species) selected from acrylate, carboxyl, hydroxyl, and carbonyl moieties. These groups are capable of forming coordinate bonds with metal ions. However, other polymers without these groups may also be used depending on the specific criteria, for example a suitable polymer may be polyvinylidene fluoride (PVDF) or styrene butadiene rubber. In any event, where a dative bond is desired between the metal coordination complex and the binder, it is even more preferred that the binder be selected from the group consisting of polyvinylpyrrolidone, carboxymethylcellulose, polyacrylic acid (PAA), poly (methacrylic acid), maleic anhydride copolymers including poly (ethylene and maleic anhydride) copolymers, polyvinyl alcohol, carboxymethyl chitosan, natural polysaccharides, xanthan gum, alginates, and polyimides. Most preferably, the binder is PAA. In an alternative embodiment, where it is desired that the binder moiety contain nitrogen atoms, a suitable polymer is polyacrylonitrile.

It will be clear to the skilled person that the proportions of the different components of the composite material are not limitations for forming a homogeneous composite material precursor formulation. At one extreme, a relatively low percentage of the first active material and/or the second active material as nanoparticles/nanofillers may be added to a bulky matrix. At the other extreme, one, two, three, or more different types of active materials may comprise a bulk composite precursor formulation. In the latter case, the supplemental binder may be a relatively low percentage of the composite material. In one embodiment, no binder is required in forming the metal-coordination complex mediated composite.

The term 'granule' or 'particulate' is generally intended to include a range of different shaped materials. The particles may be any shape such as, but not limited to, spheres, cylinders, rods, wires, tubes. The particles may be porous or non-porous.

Preferably, the particles of the first active material and/or the second active material are nano-sized or micro-sized. The term "nanosized" is intended to include number average particle sizes of about 1nm to about 1000 nm. The term "micron-sized" is intended to include number average particle sizes of about 1m (1000nm) to about 50m (50,000 nm). In the case of "nano-sized" particles, the particles of the first and/or second active materials are nano-shaped particulate materials such as nanoparticles, carbon, silicon or other nanotubes, graphene sheets, silicon, carbon and other nanocomposites, nanorods, nanowires, nanoarrays, nucleocapsid structures, and other hollow nanostructures. It is generally preferred that the particles be substantially spherical in shape, but from a shape standpoint, it will be recognized that the distribution of such nano-sized materials in the composite and precursor formulations will be different, taking into account some constant mixing conditions. With smaller and smaller particles, the surface/volume ratio increases, which affects the interfacial properties and the aggregation behavior.

Preferably, the particles of the first active material and/or the second active material have a number average particle size of at least 10 nm. More preferably, the particles have a number average particle size of at least 30 nm. Even more preferably, the particles have a number average particle size of at least 50 nm. Most preferably, the particles have a number average particle size of at least 70 nm.

Preferably, the particles of the first active material and/or the second active material have a number average particle diameter of up to 50,000 nm. More preferably, the particles have a number average particle size of up to 10,000 nm. Even more preferably, the particles have a number average particle size of up to 5000 nm. Most preferably, the particles have a number average particle size of up to 3000 nm.

It is to be understood that the particles have a number average diameter with a lower limit selected from any of about 1nm, 10nm, 30nm, 50nm, or 70 nm; and the upper limit is selected from any one of about 50,000nm, 10,000nm, 5000nm, or 3000 nm. Most preferably, the number average diameter is in the range of 100nm to 5,000nm, depending on the desired improvement.

It will also be understood that composite precursor formulations and composites are contemplated in which the first active material and/or the second active material are provided in addition to solid particulates. For example, the active material may have a porous structure or a fibrous structure. In this embodiment, the surface of the active material is at least partially coated with the metal coordination complex.

In still other embodiments, the surface of the first active material and/or the second active material exhibits nanostructured or nanopatterned features. The term 'nanopatterned' is intended to include features in the size range of 1 to 1000 nm. In these embodiments, the surfaces or nanopatterned features of these nanostructures are at least partially coated with a metal coordination complex.

In one embodiment, the liquid carrier is an aqueous or organic solvent based liquid carrier. The scope of the present invention is not particularly limited to the nature of the liquid carrier, as a wide variety of liquid solvents will be suitable for different active materials. In certain embodiments, liquid (at room temperature) ketones, alcohols, aldehydes, halogenated solvents, and ethers may be suitable. In a preferred embodiment, an alcoholic or aqueous/alcoholic liquid carrier is preferred. Such alcohols may suitably include methanol, ethanol and isopropanol.

It is believed that the layer of metal coordination complex formed on or around the first active material and/or the second active material acts to improve the dispersion and distribution of the various materials and optional other components of the composite precursor formulation during mixing. In one embodiment, the mixing forms a dative bond with a functional group that can act as a ligand on the surface of the first active material and/or the second active material. The metal coordination complex coating alters the surface chemistry of the first active material and/or the second active material, such as the presence or absence of surface charge, density and distribution, and overall hydrophobic and hydrophilic balance, thereby minimizing any interfacial distinction between the two.

Improving the dispersion and distribution of the first active material and/or the second active material in the composite precursor formulation and the composite material formed therefrom is shown herein to, in one embodiment, improve battery performance, such as providing higher energy density, faster charge and discharge cycles, and providing longer cycle life. However, it will be appreciated that the invention is not limited to use in forming composite materials for electrodes only, but has more general application in facilitating the formation of homogeneous conductive composite material precursor formulations comprising a wide range of first and/or second active materials which have different properties such that they do not otherwise naturally form a homogeneous mixture.

Where the surface chemistry of the first active material and/or the second active material needs to be converted to be more hydrophobic, coordinating ligands may be present on the metal coordination complex, which may be electrically conductive hydrophobic ligands (R-X), where X coordinates to the metal ion and thus X may be any electron donating group capable of forming a coordination bond with the metal ion. To help form a more hydrophobic surface chemistry, it is desirable that "R" be a hydrophobic group, which is preferably also potentially conductive and is any conjugated polymer, short chain form of such polymer, or multi-conjugated small molecule that can be used as a hydrophobic ligand for binding a metal coordination complex to a hydrophobic surface, where the hydrophobic/conductive ligand is bound to the hydrophobic surface through non-covalent and non-coordinating interactions, and the remaining metal coordination sites are available to present a coordination sphere to bind conductive materials. Alternatively, these short chain forms of such polymers or small molecules can serve as a conductive interface between the metal coordination complex and the conductive material.

Examples of such polymers are polyacetylene, polypyrrole, polyaniline, poly (p-phenylene vinylene), poly (alkylthiophene), poly (3, 4-ethylenedioxythiophene), polycarbazole, polyindole, polyaza, polyfluorene, polyphenylene, polypyrene, polyazulene, polynaphthalene and copolymers thereof. Small molecule precursors of these polymers and copolymers, and shorter oligomeric units (dimers, trimers, tetramers, pentamers, hexamers, heptamers, octamers, etc.) are preferred.

It will be appreciated from the above description of the first aspect that, although not so limited, the first active material and the second active material are preferably materials that can be combined to form a conductive composite material, such as a material suitable for forming a conductive interface (such as, for example, an electrode).

The first and second active materials and the metal coordination complex can be dry mixed as previously described.

In an alternative embodiment, the method includes the step of combining the first active material and the second active material with a metal coordination complex in a liquid carrier.

The liquid carrier may be as previously described for the first aspect.

Agitation may be vibration, mechanical mixing, rotation, stirring, centrifugation, and the like.

It is recognized that the first active material and the second active material can be added to the liquid carrier in any order, and that when the metal coordination complex is added thereto, there may be no active material, one or both active materials present in the liquid carrier. That is, as long as the first active material and the second active material contact the metal coordination complex in the liquid carrier, an appropriate uniform composite precursor formulation can be produced regardless of the order of addition.

In certain embodiments, the metal coordination complex is applied to the particles of the first active material and/or the second active material prior to any aggregation, in which case at least a portion of the surface of the particles of the first active material and/or the second active material is coated with the metal coordination complex. Preferably, the particles are encapsulated by a metal coordination complex.

In an alternative embodiment, the metal coordination complex may be introduced after at least some of the particles of one of the first active material and/or the second active material are mixed and aggregated. In this case, at least a portion of the surface of the other particles of the first active material and/or the second active material is coated with a metal coordination complex. Preferably, the other particles are encapsulated by a metal coordination complex.

In one embodiment of the above aspect, the metal coordination complex is bound to the first active material and the second active material via a mediator, such as, for example, a binder.

The composite material of the third aspect may be formed at least in part from the composite material precursor formulation of the first aspect.

One of ordinary skill in the relevant art will recognize that such a composite or nanocomposite material may be used in one non-limiting embodiment to form at least a portion of a conductive interface. In one embodiment, the composite precursor formulation may be used to form one or both of the anode or cathode electrodes, and may be formed from one or more active materials, such as those described previously for the first aspect, generally for either. Thus, in this embodiment, the composite material will be a component of an electrode, such as a coating on a charge collection substrate. The use of metal coordination complexes, whether the anode or cathode, improves the uniformity of the electrode material, which is believed to result in improved performance and mass reproducibility of batteries and other energy storage devices using such nanocomposites.

The elasticity imparted by the metal coordination complex to the active material to which it is bonded, as well as the inherent conductivity of the metal coordination complex, provide it with a particular effectiveness in conducting interfaces.

In a fourth aspect, the present invention relates to a method of forming a conductive interface between two or more active materials, or between at least one active material and a substrate, comprising the steps of: (i) contacting at least one active material and/or substrate with a metal coordination complex; and (ii) mixing the active materials or mixing the substrate with at least one active material or coating the substrate with at least one active material, thereby forming a conductive interface, and wherein at least two active materials or one active material and the substrate have at least one surface property different from each other.

The following description applies equally to the fourth and fifth aspects.

It is recognised that the method of the fourth aspect may result from the use of the composite precursor formulation of the first aspect. That is, when the method forms a conductive interface from at least two active materials, those active materials will have different surface properties from each other, as described for the first aspect. When the method of the fourth aspect employs one active material and a substrate, the active material will preferably have at least one surface property that is different from that of the substrate (so, in this aspect, the substrate may be considered a particular type of active material).

Furthermore, when the conductive interface is formed by the method of the fourth aspect, it may be formed from or comprise the composite material of the third aspect. That is, the conductive interface can include a first active material and a second active material (in this aspect, one of which is a substrate) that form a composite with the metal coordination complex. In this embodiment, the composite material is electrically conductive, thereby forming an electrically conductive interface.

The formed conductive interface is stronger and/or maintains superior conductivity in use, regardless of which of the active materials or substrates the coating of the metal coordination complex is applied to, or even if it should be applied to some supplemental binder material prior to contact with one of the active materials or substrates, as compared to the same interface formed without the inclusion of the metal coordination complex.

In general, in any of the above aspects, the metal coordination complex includes a metal ion having one or more coordination sites occupied by ligands and one or more coordination sites available for binding to an active material and/or substrate of the conductive interface.

Preferably, the metal coordination complex is coated on the active material such that the metal coordination complex includes at least one ligand that is datively bonded to a metal ion of the complex, and the metal ion has a surface dative bond to the active material.

In one embodiment, the metal coordination complex may form a coordinate bond with another component of the conductive interface. Such additional components may include current collectors, additional active materials or binder materials. Regardless of the nature of the components, the metal coordination complex will be able to form a coordinate bond with the surface of such materials to form a conductive adhesive interface. Although some materials (such as metals and plastics) are not considered to have the potential to form dative bonds, they typically have oxygen species on their surface because they are in an oxygen-containing atmosphere.

In one embodiment, the substrate may be a spacer. The separator may be constructed of polypropylene or other materials, such as those commonly used to separate electrodes.

In further embodiments, additional substrates may be present, and, in one embodiment, additional separators, such as are currently known in batteries.

The separator may include nonwoven fibers, polymers, polymer films, and naturally occurring substances. In one embodiment, the separator may be selected from the group consisting of: cotton, nylon, polyester, glass, polyethylene, polypropylene, polytetrafluoroethylene, PVC, rubber, asbestos, and wood.

Advantageously, in the case of the fourth and fifth aspects, the coating of the metal coordination complex around the particles of active material acts to maintain a conductive interface when coated on the charge collector electrode substrate to form an electrode, despite the tension exerted on the system by the cyclic intercalation of electrolyte (such as, for example, small charge-carrying ions, including lithium, commonly used in electrochemical cells). That is, by effectively bridging the surface of the material with the current collector, the metal coordination complex coating acts to relieve stress and strain associated with expansion and contraction of the active material and minimize or prevent degradation and breakage of contact between the materials. This unexpected effect may provide long cycle life for active materials with higher energy density, faster charge and discharge cycles.

Such coatings of active materials have not previously been used to form stronger adhesive layers at their interfaces with other materials when forming conductive interfaces, which is a highly desirable requirement if the active materials may undergo physical dimensional changes such as cyclic expansion and contraction. In addition, conductive metals such as aluminum, copper and silver can easily oxidize at their surfaces and the oxide layer will result in poorer conductivity. Furthermore, conductive polymers (such as polyacetylene, polypyrrole, polyaniline, etc.) do not readily form binding interactions due to lack of appropriate functionality. In contrast to passive bonding, when metal coordination complexes are employed that can maintain conductivity at all times, the strong bonding interface formed is desirable in many applications where a predetermined electron and/or ion flux is required.

In one embodiment, the substrate may be mixed with the active material. The metal coordination complex may have been applied to or contacted with one or both of the substrate and the active material. For example, the substrate may be polypropylene fibers forming the separator. These may contact the metal coordination complex and then mix or otherwise contact the active material.

In one embodiment, the particles of active material are at least partially coated with a metal coordination complex. However, in an alternative embodiment, the particles of active material are substantially completely coated with the metal coordination complex. It is not critical whether the one or the other active material or the substrate forming the conductive interface is initially coated with the metal coordination complex, or whether the interface is formed and then the metal coordination complex is applied. As previously discussed, the dative bond of the metal coordination complex enhances the stability of the interface, and this can be formed in a number of ways.

In one embodiment of the fourth aspect, the active material and/or the substrate is contacted with the metal coordination complex, and then the active material is mixed or coated on the substrate. Although the metal coordination complex may contact the active material and/or the substrate after the active material is coated on the substrate, it is preferable that the active material and/or the substrate, particularly the active material, contact the metal coordination complex before the active material is coated on the substrate.

In certain embodiments, the conductive interface may include both conductive and non-conductive materials, including porous or fibrous structures, allowing for ion or electron transfer in the electrolyte. One of the active material or the substrate may be formed of such a conductive material or a non-conductive material.

Although much of the discussion herein refers to one active material mixed with or coated on a substrate with a different active material, it will be clear to the skilled artisan that these embodiments are exemplary and not intended to limit the scope of the invention. It should be understood that multiple interfaces may also be included, including, for example, a first active material and a second active material and a substrate, a second and a third active material and a substrate, a third and a fourth active material and a substrate, and the like. Although the first active material or substrate is coated with the metal coordination complex, it will be appreciated that the second, third and fourth active materials and/or substrates may be present as part of the conductive interface in any combination, coated or uncoated. The active material and the substrate comprising 1, 2, 3 or more layers may be in any shape (film, strip, etc.) and thickness as required by the application, as long as at least one interface is stabilized by the coordinate bond of the metal coordination complex in the manner described above.

The metal coordination complex can be coated or applied on the active material to form a thin film on the surface of the active material. The film may be formed as a single layer. However, thicker films can also be prepared if desired. The thickness of these coatings may be increased depending on the formulation used. This may be accomplished by forming a thicker layer of metal coordination complex, such as forming a lattice of metal coordination complex on the surface of the active material, and/or forming a multilayer laminate structure on the surface of the active material by applying an additional coating layer, such as an additional metal coordination complex, a polymer, or an adhesive. Additional coating layers may be used to alter the overall coating characteristics. Thus, the characteristics of the active material and the structure including the conductive interface can be adjusted by controlling the thickness of the layer of the metal coordination complex.

In one embodiment, the thickness of the layer of metal coordination complex formed on the active material or substrate is less than about 250nm, preferably less than about 100nm, more preferably less than about 50nm, even more preferably less than about 20nm, still even more preferably less than about 10nm, and most preferably less than about 5 nm.

The metal coordination complex can coordinate with, preferably, any electron donating group on the surface of the active material to bind the metal coordination complex to the active material. Thus, at least one active material includes a surface having electron-donating groups, and the metal ions of the metal coordination complex layer are bonded to these electron-donating groups of the active material via a coordinate bond, as will be described herein.

In certain embodiments, the active material is in the form of a population of particles. The population may be processed to form a slurry, which may include a binder, and which is then applied to a continuous substrate surface, such as copper, aluminum, or another conductive or semiconductive substrate. As discussed, the active material or substrate may be non-conductive, but its structure (e.g., its porosity) allows for electron and/or ion diffusion. The metal coordination complex may be mixed with the active material slurry and the binder, and thereby form a coating or layer around the active material particles with bonds available thereto and also bonds available to the binder, and then coated on the substrate, the substrate surface.

One of ordinary skill in the relevant art recognizes that when the conductive interface is part of an electrode, then the electrode can be either an anode or a cathode, and can be formed of materials typically used for one of them (forming the active material and the substrate). In each case, the active material comprises a surface, typically presented by particles thereof, and the metal ions of the metal coordination complex are capable of forming a coordinate bond with the surface. Preferably, the surface of the active material comprises nitrogen, oxygen, sulfur, hydroxyl or carboxylic acid species having a lone pair of electrons for forming a dative bond. Most preferably, the surface comprises an oxygen species. In general, oxygen species are preferred as the surface of the active material, and can be readily oxidized to include an oxide layer, or functionally can be considered an oxide, if desired. Thus, in a preferred embodiment, the surface of the active material is an oxide or partially oxidized surface.

In one embodiment, the substrate may be selected from the group consisting of: metals, intermetallics, metalloids, porous polymers, and conductive polymers. Preferably, the substrate is selected from the group consisting of: aluminum, copper, silver, gold, platinum, iron, zinc, nickel and their alloys or conductive polymers or any other conductive material. Suitable conductive polymers may include polyacetylene, polypyrrole, polyaniline, poly (p-phenylene vinylene), poly (alkylthiophene), poly (3, 4-ethylenedioxythiophene), polycarbazole, polyindole, polyaza, polyfluorene, polyphenylene, polypyrene, polyazulene, polynaphthalene, and copolymers thereof. Preferably, the substrate is copper when the conductive interface is part of an electrode, the electrode being an anode, and the substrate is aluminum when the electrode is a cathode.

When the conductive interface is part of a semiconductor arrangement, then the active material may be formed from any suitable semiconductor material comprising two or more elements. In one embodiment, at least one element is a group III element selected from the group consisting of indium, aluminum, and gallium, and another element may be a group V element selected from the group consisting of nitrogen, phosphorus, arsenic, and antimony. In certain embodiments, the active material is a group III nitride, a group III arsenide nitride, or a group III arsenide-phosphide. In certain embodiments, each active material is selected from the group consisting of: gallium nitride, indium gallium nitride, aluminum indium gallium nitride, indium aluminum nitride, aluminum gallium nitride, indium gallium arsenide nitride, aluminum indium gallium arsenide nitride, indium gallium arsenide phosphide, indium aluminum arsenide, indium aluminum gallium arsenide, titanium nitride, tantalum nitride, titanium oxide, tantalum oxide, silicon nitride, silicon dioxide, boron, phosphorus, and arsenic doped crystalline and amorphous silicon, and copper, aluminum, gold, silver, and alloys thereof.

Substrates suitable for semiconductor arrangements may include sapphire, zinc, glass and other silicon-based substrates. In the case of several semiconductor chips stacked together to form a combined system, the active material on the substrate may in turn become a substrate for the active material coming in later.

Potential uses and advantages of the conductive (which term explicitly includes semiconductor interfaces) interface of the present invention in semiconductor applications, including metal-ligand complexes as previously described, may include, but are not limited to, (i) use as an adhesion layer between the backside of a chip (e.g., materials such as aluminum, copper, aluminum copper, gold, or bare crystalline silicon and amorphous silicon, GaN, GaAs) and PVC foils; (ii) as a conductive material between two active species (e.g., two or more semiconductor chips, i.e., chips on a chip assembly); and (iii) as an adhesion promoter between the ceramic or copper substrate and the semiconductor backside.

In one embodiment of any one or more aspects described herein, when the active material comprises both silicon nanopowder and conductive carbon black, then the substrate may optionally not be a copper foil.

In a further embodiment, when the active material further comprises a binder, then when the active material comprises both silicon nanopowder and conductive carbon black and the substrate is copper foil, the binder may optionally not be poly (acrylic acid) (PAA).

In one embodiment of the invention, optionally neither the first active material nor the second active material is a metalloid.

It will be appreciated that metal coordination complexes used as components of conductive interfaces, for example in electrodes or including electrode-separator interfaces, provide certain advantages in operation, and in particular improve adhesion of the active material or interface to the underlying substrate. In various embodiments, the conductive interface formed according to the fourth aspect may: (i) improving the physical adhesion or bonding of the active materials to each other and to the underlying substrate; (ii) improve or increase ionic conductivity and electrical conductivity at the conductive interface; (iii) improved or maintained stability of the active material; (iv) the solubility of certain electrode materials is reduced; (v) (vii) increased cycle life of the battery, and (vi) reduced overall battery waste.

The fourth and fifth aspects will now be described with particular reference to forming a conductive interface in a silicon anode. However, it will be appreciated that the concepts described below are applicable to, but not limited to, any other conductive interface of a structure used in various applications where supporting and maintaining conductivity at the interface is important.

Silicon anodes comprising metal coordination complexes can be produced in various ways. As an example, in one production method for a silicon anode slurry, three components are used: (i) silicon particles, (ii) carbon/graphite particles, and (iii) a binder, such as polyacrylic acid (PAA). The slurry is then bonded to a current collector. The metal coordination complex may be added to the silicon particles to form an activated silicon material, which may then combine the carbon particles and PAA. Alternatively, or in addition, the carbon particles may be coated with a metal coordination complex and then the silicon particles and PAA combined. Alternatively, the metal coordination complex may be added to the binder to form a metal-ligand-binder complex, which in turn binds the silicon and carbon particles. Alternatively, the metal coordination complex may be added directly to and mixed with the pre-existing mixture of silicon particles, carbon particles and PAA. Alternatively, the silicon particles and the carbon particles and/or the binder may both be coated with the metal coordination complex, and, optionally, metal coordination complexes of different properties may be used depending on the particular active material to be coated.

Similarly, in bonding the metal coordination complex-related slurry to the current collector, the current collector itself may be pre-activated with one or more metal coordination complexes.

In the case of silicon-based anodes, the ability of the metal coordination complex to form coordinate bonds with adjacent atoms creates a stable structure that is capable of forming and reforming those bonds in a dynamic chemical environment. The anode and cathode electrodes allow lithium ions to enter or exit from the interior of the active particles constituting those electrodes. During insertion (or intercalation), ions enter the electrode. During the reverse process, extraction (or de-intercalation), ions come out of the electrodes. When the lithium ion type battery is discharged, positive lithium ions move from the negative electrode (in this case, a silicon type electrode) and enter the positive electrode (a compound containing lithium). When the battery is charged, the opposite is true.

Clearly, then, when charge is accumulated, the silicon must expand to store lithium ions. The expansion accompanying lithium uptake is always a challenge when designing high capacity lithium-ion anode materials. Among lithium-ion storage materials, silicon has the highest capacity, but expands 3-4 times in volume when fully charged. This expansion causes the electrical contact with the anode to break rapidly. The metal coordination complexes as described herein form a coordination force between the various components of the silicon anode material. It is believed that the combined adhesion resists expansion and contraction in the active material. Furthermore, even if there is some breakage of these coordination bonds during expansion, coordination bonds may be formed after shrinkage. In addition, the same benefits apply to the active material and current collector conductive interface to prevent delamination of the active material from the current collector. Thus, the fourth aspect provides a conductive interface that can be used to form an electrode of higher stability and longer lifetime. In addition, the metal coordination complex facilitates free electron movement.

The benefits of metal coordination complex coating are not limited to anodes. The cathode also faces the same challenges surrounding maintaining a good conductive interface, and the above-mentioned benefits of using metal coordination complexes also allow for more efficient performance of the cathode.

The following comments on the metal coordination complex, the related ligand and the adhesion thereof apply to all of the first to sixth aspects.

In one embodiment, the metal ion of the metal coordination complex is selected from the group consisting of: chromium, ruthenium, iron, cobalt, aluminum, zirconium, and rhodium.

Preferably, the metal ion is chromium.

The metal ion can be present in any useful oxidation state. For example, chromium is known to have the following oxidation state: I. II, III, IV, V or VI.

In embodiments where the metal ion is a chromium ion, it is preferred that the chromium has an oxidation state of III.

The metal ion may be combined with a counter ion, such as an anion selected from the group consisting of: chloride, acetate, bromide, nitrate, perchlorate, alum, fluoride, formate, tetrafluoroborate, hexafluorophosphate, and sulfate, which may be coordinated or non-coordinated (weakly coordinated). In one embodiment, the counterion is a non-coordinating anion. In another embodiment, the counterion is a coordinating anion.

In certain embodiments, mixtures of different metal ions may be used, for example, to form a plurality of different metal coordination complexes. In this case, preferably at least one metal ion is chromium.

Metals are known to form a series of metal coordination complexes. Preferred ligands for forming metal coordination complexes are those that include nitrogen, oxygen, or sulfur as a group that forms a coordinate bond. More preferably, the group forming the coordinate bond is oxygen or nitrogen. Even more preferably, the group forming the coordinate bond is an oxygen-containing group. Still even more preferably, the oxygen containing group is selected from the group consisting of: an oxide, hydroxide, water, sulfate, phosphate, or carboxylate.

The metal coordination complexes may also be further stabilized by crosslinking the metal ions of the individual complexes with one another to form larger oligomeric metal coordination complexes. Thus, in one embodiment, the metal coordination complex is an oligomeric metal coordination complex. Preferably, the oligomeric metal coordination complex is a chromium (III) oligomeric metal coordination complex.

In one embodiment, the metal coordination complex comprises, as a ligand, a bridging compound which is coordinately bound to at least two metal ions. Preferably, this results in the formation of oligomeric metal coordination complexes.

In certain embodiments, mixtures of different ligands can be used to form a metal coordination complex or complexes. Different ligands may have different functions, for example, forming a plurality of different metal coordination complexes, bridging between metal coordination complexes, crosslinking metal ions, or providing a surface for forming coordinate bonds with various components of the composite.

In one exemplary embodiment, the metal coordination complex is an oxygen bridged chromium (III) complex. The complex may optionally be further oligomerized with one or more bridging linkages such as carboxylic acid, sulfate, phosphate, and other polydentate ligands.

The metal coordination complexes will be discussed below in view of the available variations of the synthesis method and thus the possibility of differences being achieved in the final product.

The metal coordination complex may be formed by providing the following conditions: the conditions are used to form an electron donating group for bridging or otherwise connecting or bonding two or more metal ions. This may be accomplished by providing a pH of less than pH 7, such as less than pH 6 or less than pH 5, preferably between about 1.5 to 7, or about 2 to 7, or about 3 to 7 or about 4 to 7, or about 1.5 to 6, or about 2 to 6, or about 3 to 6 or about 4 to 6, or about pH of less than pH 7 to the composition formed by the metal coordination complex contacting the surface of the active material.

Various chromium salts such as chromium chloride, chromium nitrate, chromium sulfate, chromium perchlorate may be used to form the metal coordination complex. These salts are mixed with alkaline solutions (such as potassium hydroxide, lithium hydroxide, sodium bicarbonate, sodium sulfite, and ammonia) to form different metal coordination complexes. Organic reagents which can be used as bases, such as ethylenediamine, bis (3-aminopropyl) diethylamine, pyridine, imidazoles, can also be used. The size and structure of the metal coordination complex can vary with pH, temperature, solvent, and other conditions.

In particular, by changing the metal salt and reaction environment, it is possible to regulate the bonding of metal coordination complexes to oxides (such as silica) and other solid substrates, and to present coordination layers to bind different active materials in the formulation that would otherwise not be uniformly dispersed. Although the individual coordination interactions between the metal coordination complex and a given active material are relatively weak, a large number of coordination forces produce very strong interactions. Individually, each coordination interaction may break at some point due to a local stressor. However, it is highly unlikely that a localized stressor will break all or even most of the multiple coordination bonds. Thus, once the stressor is relaxed or removed, the broken bond can reform.

The oligomeric metal coordination complex may be preformed and applied to the liquid carrier, or formed in situ in the presence of the active material. In this embodiment, the ligand is capable of forming multiple coordinate bonds with multiple metal ions to effectively bridge or crosslink the metal ions. That is, the ligand may form a dative bond with two or more metal ions, thereby linking one metal ion to another metal ion.

Exemplary oxygen bridged chromium structures are provided below:

when applied to a liquid carrier in the presence of at least one of the first or second active materials and/or the substrate, at least one of the water or hydroxyl groups on the respective metal coordination complex is replaced with a coordinate bond to the surface of the active material. This is illustrated below, where "X" represents a dative bond to the surface of the active material.

It will also be appreciated that a plurality of water or hydroxyl groups may be replaced by dative bonds to one of the first or second active materials or the surface of the substrate, e.g., the respective chromium ions may form dative bonds to the active material or the surface of the substrate.

In addition, water and/or hydroxyl groups may be replaced by coordinate bonds with additional components of the formulation, such as additional active materials or binders.

In one embodiment, the step of preparing the electrode comprises casting the electrode from a composite precursor formulation comprising an active material and a metal coordination complex. A precursor formulation comprising an active material may be formed as described in any one or more embodiments of the first and second aspects.

The electrically conductive interface of the electrode may be formed at least in part from the composite precursor formulation of the first aspect or the composite of the third aspect or the method of the fourth aspect. The materials and methods may be as previously described for any of those aspects.

It is to be understood that in the present description the invention discloses and defines all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the present invention.

Examples

Example 1: metal coordination complex coated silicon nanoparticles

Metal coordination complex solutions were prepared using different salt and base combinations.

Solution 1

In this example, chromium perchlorate hexahydrate (45.9g) was dissolved in 480ml of purified water and mixed well until all solids were dissolved. Similarly, 8ml of an ethylene diamine solution was added to 490ml of purified water. The solutions were combined and stirred at room temperature overnight, and then left to equilibrate the pH to about 4.5.

Solution 2

Similarly to the above, different ratios of chromium perchlorate and ethylene diamine solutions can be used to produce solutions having different phs, such as pH 4.0, pH 5.0, or some other pH.

Solution 3

In this example, chromium chloride hexahydrate (26.6gm) was dissolved in 500mL of purified water and mixed well until all solids were dissolved. The pH was slowly adjusted to pH 4.5 (or some other target pH) with 1M NaOH or LiOH.

Solution 4

In this example, chromium chloride hexahydrate (26.6 grams) was dissolved in 480ml of purified water and mixed well until all solids were dissolved. Similarly, 8ml of ethylene diamine solution (or other amount) was added to 490ml of purified water. The solutions were combined and stirred at room temperature overnight, and then left to equilibrate the pH to about 3.8 (or other pH may be selected if desired).

Solution 5

In this example, chromium perchlorate (45.8g) was dissolved in 150ml of isopropanol and mixed well until all solids were dissolved. Similarly, 2-naphthoic acid (5.6g) was suspended in 100ml of isopropanol and finally powdered potassium hydroxide (6.17g) was added slowly with vigorous stirring. After the suspension was formed, the chromium perchlorate solution was added dropwise with stirring, and then the resulting mixture was allowed to flow in countercurrent and maintained for at least 60 minutes. Upon cooling, the reaction formed a dark green coordination complex of the chromium salt with 2-naphthoic acid. Similarly, other conjugated acids with conductive potential can be incorporated into the metal coordination complex by the methods described above.

Example 2: metal coordination complex activated current collector

Preparation of metal coordination complexes on copper and aluminum current collectors

After pre-rinsing with acetone and ethanol, copper and aluminum current collectors were treated with 5mM metal coordination complex solutions (such as those described in example 1). To obtain the desired working concentration, the metal coordination complex examples using solutions 1 to 3 were diluted in water while the examples such as in solution 4 were dissolved in isopropanol/water (1: 1). The current collector was left to stand in each metal coordination complex solution for 1 hour, rinsed with water or isopropanol/water (1:1), and dried in a drying oven for 1 hour or overnight before further processing.

The metal coordination complex coated current collector is then allowed to stand in the polymer, particles or other components including the active material. As an example, in the case of a polymer such as polyacrylic acid (PAA), a 1% aqueous solution of PAA is prepared and the current collector is immersed in the solution for 1 hour. After extensive rinsing with water, these modified current collectors were dried in air for at least 1 hour and compared to those not treated with the metal coordination complex binder.

Contact angle analysis of metal coordination complex treated and non-metal coordination complex treated current collectors.

Contact angle analysis was performed on the surface of the metal coordination complex treated and untreated current collectors using 20 μ L milliQ water drops on a Dataphysics tool. Contact angle measurements were performed in 9 to 12 replicates. As shown in fig. 1 and 2, the wettability of metal coordination complex treated copper and aluminum current collectors and polyacrylic acid (PAA) adhesion make a significant difference as shown by the change in contact angle (θ). The untreated copper current collector is relatively hydrophobic as indicated by its high contact angle (θ ═ 80 °), but the contact angle drops significantly upon metal coordination complex treatment. Interestingly, it is noted that wettability and adhesion of polyacrylic acid to copper surfaces is affected by the pH at which the metal coordination complex is formed (which affects the oligomer population in the metal coordination complex solution) and, to some extent, the drying process. Similar features are seen with aluminum current collectors (fig. 2).

Example 3: composite material of silicon and carbon particles

Preparation of Metal coordination Complex silicon particles (1-3 μm)

In this example, a 50mM (final concentration) solution of the metal coordination complex is used. Silicon (Si) powder (1-3 μm in size) was purchased from US Research Nanomaterials, USA. A20% w/w silicon slurry was prepared by ball milling 1-3 μm silicon powder with a metal coordination complex solution in an alumina jar.

Preparation of silicon particles (without Metal coordination Complex)

By ball milling 1-3 μm silicon powder and ddH in an alumina jar₂O to prepare a 20% w/w silicon slurry.

Preparation of composites of silicon and carbon particles with and without metal coordination complexes

The metal coordination complex coated and uncoated silicon nanoparticles prepared above were mixed with timal graphite and Super P conductive carbon black purchased from MTI Corporation, USA and average M purchased from Sigma-Aldrich, USA_w450,000D of poly (acrylic acid) (PAA). The silicon nanoparticles (with or without metal coordination complexes) are mixed with a quantity of Super P-carbon equal to the dry weight of the silicon nanoparticles. By adding ddH₂O, diluting the slurry to a solids content of 12.5% w/w. The alumina can was placed in a ball mill and run at 450rpm for 56 hours. Will ddH ₂Average M in O_wSufficient 5% w/v poly (acrylic acid) (PAA) solution of 450,000D was added to the slurry to achieve a large amount of poly (acrylic acid) equal to half the mass of Super P carbon and 10% w/w solids. The slurry was ball milled overnight at 200 rpm. This produced a slurry with a Si Super-P PAA ratio of 40:40:20 (wt%). The amounts of Si, Super-P and PAA can be adjusted to produce slurries comprising different ratios. The slurry was densified in a furnace at 90 ℃ until a final solids of about 25% w/w was reachedVolume content.

SEM analysis of silicon and carbon particle composites with and without metal coordination complexes.

Scanning Electron Microscope (SEM) imaging and energy dispersive X-ray spectroscopy (EDS) analysis were performed using JEOL 7001F. Secondary Electron Image (SEI), back reflection image (comp), and EDS data were collected.

Slurries prepared with metal coordination complexes clearly show a more uniform distribution of particles (silicon appears brighter than carbon on the back reflection image due to its higher atomic weight), a uniform distribution of white silicon in a reproducible pattern (fig. 3a and 3c), and no reproducible pattern in slurries prepared without metal coordination complexes (fig. 3b and 3 d).

Example 4: high capacity LiNiCoMnO ₂Composite of particles and carbon particles

Preparation of Metal coordination Complex lithium Metal oxide particles

In this example, a 50mM (final concentration) solution of chromium metal coordination complex is used. High capacity lithium metal oxide (LiNiCoMnO)₂) The pellets were purchased from MTI Corporation, USA. Preparation of 10% w/w LiNiCoMnO by adding 100mM metal coordination complex solution to dried lithium metal oxide particles₂And (4) slurry. The slurry was mixed overnight at 550rpm using a magnetic stirrer. The overnight slurry was transferred to a centrifuge tube and centrifuged at 4,000g for 10 minutes to separate the solids from the solution. Remove 90% of the supernatant from the starting volume and add ddH at pH 4.5₂And replacing by O. The pellet was resuspended using physical agitation and bathed with high levels of ultrasound for 10 minutes. This washing step was repeated and followed by a second centrifugation step, the supernatant was removed from the solution and washed with 10% v/v isopropanol ddH₂O solution was replaced to achieve a slurry of 10% w/w solids content. The slurry bath was sonicated for an additional 10 minutes to fully disperse the particles.

Preparation of a composite of lithium metal oxide and carbon particles with and without a metal coordination complex

Metal coordination complex coated lithium metal oxide particles prepared as described above, and untreated lithium metal oxide The particles were combined with TIMAL Super C45 conductive carbon black purchased from MTI Corporation, USA and average M purchased from Sigma-Aldrich, USA_wPoly (acrylic acid) (PAA) at 450,000D. Lithium metal oxide particles (with or without metal coordination complexes) were transferred to a 250mL Erlenmeyer flask using a magnetic stir bar. Super C45 carbon was added in a ratio of 7:85 dry weight of lithium metal oxide to achieve a solids content slurry of 10% w/w. The slurry flask was placed on a magnetic stirrer and mixed overnight at 550 rpm. 5% w/v of average M in proportion to Super C45 carbon 8:7_wddH of Poly (acrylic acid) (PAA) 450,000D₂The O solution was added to the slurry and resulted in a solids content of 8.5% w/w. The slurry was allowed to mix overnight at 550 rpm. The slurry had a weight percent (wt%) of 85:7:8 LiNiCoMnO₂: Super-C45: the ratio of PAA. The amounts of Si, Super-C45, and PAA can be adjusted to produce slurries comprising different ratios. The slurry was allowed to thicken in a furnace at 90 ℃ until a solids content of about 15% w/w was reached.

SEM analysis of lithium metal oxide and carbon particle composites with and without metal coordination complexes.

It can be seen that the slurries prepared with the metal coordination complexes show a more uniform distribution of particles (LiNiCoMnO on the back reflection image due to their higher atomic weight)₂Appears brighter than carbon), white linicoomno₂Uniformly distributed in a reproducible pattern (fig. 4a and 4c), with no reproducible pattern in the slurry prepared without the metal coordination complex (fig. 4b and 4 d).

Example 5: composite material of silicon (100nm) and carbon particles

Metal coordination complex silicon particles are prepared.

In this example, as described above, 50mM (final concentration) of the metal coordination complex solution 1 was used. Silicon (Si) nanopowders (100nm in size) were purchased from MTI Corporation, USA. By mixing dry silicon nanopowder with 7.5% isopropyl at pH 4.3Alcohol ddH₂O solution, preparing 20% w/v silicon nanoparticle slurry. The slurry was placed under vacuum for 5 minutes and then 100mM metal coordination complex solution was added. The flask was heated to 40 ℃ and the slurry was mixed by a mechanical overhead mixer at 400rpm for 5 minutes. After mixing, the solution was evacuated for another 10 minutes. The slurry was further mixed overnight at 400rpm at 40 ℃. The slurry was centrifuged at 10,000g for 10 minutes to separate the solids from the solution. 70% of the supernatant was removed from the starting volume and treated with ddH pH 4.3 ₂And (4) replacing by O. The precipitate was resuspended using physical agitation and bathed for 10 minutes with sonication. This washing step was repeated, and then a third centrifugation step, the supernatant was removed from the solution. ddH of pH 4.3₂O is added to the slurry until a solids content of 20% w/v is reached. The slurry bath was sonicated for an additional 10 minutes to fully disperse the particles. Various concentrations of metal coordination complex solutions in combination with no rinsing step or different number of rinsing steps can be used to coat the Si nanoparticles.

The charge and surface change of the Si nanoparticles were evaluated by a zeta sorter.

Use ofThe zeta sorter evaluates the size and surface charge of the silicon particles. Silicon nanoparticles coated with metal coordination complexes as described above or with ddH using probe sonication₂O treatment (control). After centrifugation at 10000rpm for 10 minutes, the supernatant was removed and sonicated with ddH using a probe₂O redisperses the particles. This rinsing step was repeated a total of 3 times and the size of the activated metal coordination complex and the non-activated particles and the zeta potential were measured using a zeta sorter.

Fig. 5 and 6 show zeta potential data for silicon nanoparticles treated with two metal coordination complex formulations formed at pH 3.7 and pH 5.0, respectively. The Si particles have a negative zeta potential, as would be expected from the presence of negatively charged Si-OH groups. Metal coordination complexes that are positively charged and effectively coat negatively charged particles can form net positively charged particles. The stability of these particles under vigorous washing can be seen between figures 5 and 6. The metal coordination complex adjusted to pH 5.0 yields stable positively charged Si nanoparticles, capable of coordinating with other particles or binders. At pH 3.7, the metal coordination complex still exists on the silicon nanoparticles as shown by the reduced electronegativity of the silicon nanoparticles. By controlling the type of metal complex, as exemplified by a change in pH, it is possible to change the surface properties of the silicon nanoparticles from negatively charged, to neutral and to positively charged particles.

Composites of silicon and carbon particles were prepared with and without metal coordination complexes.

Metal coordination complex coated silicon nanoparticles and untreated silicon nanoparticles prepared as described above were mixed with TIMAL graphite and Super P conductive carbon black purchased from MTI Corporation, USA and average M purchased from Sigma-Aldrich, USA_wPoly (acrylic acid) (PAA) at 450,000D. The silicon nanoparticles (with or without the metal coordination complex) were transferred to a side arm flask with a magnetic stir bar. Super P-carbon, equal in mass to the dry weight of the silicon nanoparticles, was also transferred to the same flask. By adding ddH₂A 15% solution in isopropanol in O, the slurry was diluted to a solids content of 15% w/v. The slurry flask was placed on a heated stirrer and mixed at 400rpm for 5 minutes at 40 ℃. The flask was placed under vacuum and mixing was continued for an additional 5 minutes. The vacuum was removed and the slurry was allowed to mix for an additional 1 hour. 450kDa poly (acrylic acid) equal to half the mass of the Super P carbon was weighed and added to the slurry. The slurry was mixed overnight at 400rpm at 40 ℃. This produced a slurry with a Si Super-P PAA ratio of 40:40:20 (wt%). The amounts of Si, Super-P and PAA can be adjusted to produce slurries comprising different ratios.

SEM analysis of silicon (100nm) and carbon particle composites with and without metal coordination complexes.

Scanning Electron Microscope (SEM) imaging was performed as previously described. It can be seen that the slurries prepared with the metal coordination complexes (fig. 7a) show smoother, more regular surfaces on SEI imaging than the slurries prepared without the metal coordination complexes (fig. 7 b). The back reflection image confirms this observation (silicon appears brighter than carbon on the back reflection image due to its higher atomic weight), and the white silicon is more uniformly distributed and less clustered in the slurry prepared with the metal coordination complex (fig. 7c) than in the slurry prepared without the metal coordination complex (fig. 7 d).

Example 6: production and testing of Si anodes in coin cells with and without Metal-complexes

Preparation of battery pack slurry

Metal coordination complex coated silicon nanoparticles (100nm), and battery slurry were prepared as illustrated in example 5, with a ratio of Si: Super-P: PAA of 40:40:20 (wt%). The amounts of Si, Super-P and PAA can be adjusted to produce slurries of different formulations

Fabrication of metal coordination complex coated Si anodes in coin cell batteries

The Si slurry was cast on a copper (Cu) foil, which served as a current collector, to form a Si electrode. Next, the Si electrode was dried under vacuum, calendered and cut for button cell assembly. A similar Si electrode with uncoated Si as the active material was also prepared and used as a control with a similar mass loading (2.22-2.37 mg/cm) as the metal coordination complex coated Si electrode ²). Lithium (Li) metal as a counter electrode, and 1M LiPF₆FEC with/EC DEC DMC 1:1:1, 10% was used as electrolyte for coin cell assembly. For the charge/discharge cycling test, the coin cells were activated for 2 cycles at 0.01C (1C ═ 4,200mAh/g) and then cycled at 0.5C (1C ═ 4,200mAh/g) for the long-term stability test. The C ratio is based on the mass of Si particles in the electrode. For Li, the voltage range for the charge/discharge test was 0.005-1.50V. Charge/discharge tests were performed on a software multichannel battery tester controlled by a computer. Three duplicate cells were prepared and tested for each condition.

SEM analysis and photographs of silicon (100nm) electrodes with and without metal coordination complexes before and after cycling.

Fig. 8 shows respective Secondary Electron Images (SEI) and back reflection images (comp) for Si (100nm) electrode stripes with (c and d) and without (a and b) metal-ligand complexes after casting the slurry on a Cu-foil substrate. Cycling studies were not performed on these electrodes. Again, from the uniformity and dispersion perspective of the mixed slurry, a clear distinction can be made where the metal coordination complex slurry shows better uniformity and dispersion, while the control slurry contains poor dispersed agglomeration (with lighter color) of the Si particles. Since all slurries undergo the same ball milling process, the difference is believed to be due to the metal coordination complex coating on the Si particles.

Fig. 9 shows the difference in surface morphology and electrode structure with (c and d) and without (a and b) metal coordination complexes for electrode samples after hundreds of deep charge/discharge cycles. It can be seen that the electrode structure of the metal coordination complex sample is better maintained, while the control sample shows more fragmentation and comminution of the particles. This shows the advantages resulting from the improved homogeneity of the composite precursor formulation and from the inclusion of metal coordination complexes in the final composite formed therefrom.

FIG. 10 shows cross sections of the metal coordination complex (b) and the control sample (a) after respective charge/discharge cycles. The electrode structure and integrity of the metal coordination complex sample is significantly better maintained. As shown, in the control sample, the copper foil (top) had delaminated from the silicon active material, while the electrode incorporating the metal coordination complex had the copper foil still bonded to the silicon active material. Fig. 11 shows photographs of silicon active material with metal coordination complex (b) and without metal coordination complex, i.e. control sample (a), from disassembled half coin cells after 1000 deep charge and discharge cycles (at 0.5C, 1C ═ 4,200 mAh/g). Cells (b) incorporating the metal coordination complex remain intact, while those (a) without the metal coordination complex show significant cracking and are easily removed from the copper foil.

Fig. 12(a), (b), (c), and (d) are SEM images of: SEM images of (a)100x, (c)250x SEI mode of a disassembled electrode formed with metal coordination complex, and SEM images of (b)100x, (d)250x SEI mode of a disassembled electrode formed in a similar manner but without metal coordination complex. As before, SEM images were taken from half of the button cells disassembled after 1000 deep charge and discharge cycles at 0.5C, 1C ═ 4,200 mAh/g. The image on the sample with the metal coordination complex shows a hairlike structure corresponding to a battery separator made from fibers of polypropylene/polyethylene. In contrast, when no metal coordination complex is used, almost no separator fibers are observed. This shows that in the presence of the metal coordination complex, there is a strong bond between the active material and the separator.

Example 7: LiNiCoMnO in button cells with and without metal-complexes₂Manufacture and testing of cathodes

Manufacture of metal coordination complex coated lithium metal oxide cathodes in coin cells

Metal coordination complex coated lithium metal oxide slurries were prepared as set forth in example 4 and sent for electrode manufacture and coin cell assembly. At 13mg/cm ²Mass loading of slurry cast on aluminum (Al) foil used as current collector to form LiNiCoMnO₂And an electrode. Then, each LiNiCoMnO₂The electrodes were dried under vacuum, calendered and cut for button cell assembly. Lithium (Li) metal as counter electrode, 1M LiPF₆DEC DMC 1:1:1 and 10% FEC were used as electrolyte and polypropylene/polyethylene separators were used for coin cell assembly. For the charge/discharge cycle test, the coin cells were activated at 0.02C (1C ═ 150mAh/g) for 3 cycles and then cycled at 0.1C (1C ═ 150mAh/g) for the long-term stability test (1000 cycles). The C ratio is based on the mass of Si particles in the electrode. For Li, the voltage range for the charge/discharge test was 2.5-4.2V. Charge/discharge tests were performed on a software multichannel battery tester controlled by a computer. Three duplicate cells were prepared and tested for each condition.

SEM analysis and photographs of lithium metal oxide electrodes with and without metal coordination complexes before and after cycling.

After 1000 deep cycles, the button cells were disassembled. Removal of LiNiCoMnO₂Cathode electrode and as described in example 6, using Scanning Electron Microscope (SEM) imaging and energy dispersive X-ray spectroscopy (EDS) analysis.

Fig. 13(a) and (b) LiNiCoMnO with coordination complex from a disassembled half coin cell after 1000 deep charge and discharge cycles (at 0.5C, 1C 150mAh/g)₂Photographs of the material (a) and the control sample (b). The cell incorporating the metal coordination complex (a) was still intact with residual separator material (white spots), while the control (b) without the metal coordination complex ruptured and most of the material simply fell off the aluminum foil. FIGS. 14(a) and (b) shows LiNiCoMnO in 100X SEI mode for detached electrodes formed with and without metal coordination complexes (a) and (b)₂SEM image of the material. As previously shown in the photograph (fig. 13), there were spots of hair-like structure of the separator (polypropylene/polyethylene fibers) in those instances where there was a metal coordination complex. In the case where there is no metal coordination complex, only a small amount of such fibers is present.

Example 8: forming a GaN/sapphire interface

Gallium nitride/sapphire membranes obtained from blue glass Ltd, NSW, australia were broken down into small fragments and a portion of the fragments were immersed in a 5mM solution of metal coordination complex for 1 hour with ddH₂O rinse for 30 seconds and then dry in a vacuum desiccator for 1 hour. Metal coordination complex coated and uncoated segments (treated with water under similar conditions) were placed on top of the complete membrane to form an interface between the upper GaN (on the bottom membrane) and the bottom sapphire (on the top membrane segment). These stacked sheets were allowed to stand at 700 ℃ for 15 minutes.

After the films were allowed to cool to room temperature, they were tilted, whereupon uncoated segments were observed to immediately slide off the bottom film sheet, i.e., temperature treatment alone did not result in any interfacial bonding. The metal ligand coated segment did not slip off until the bottom membrane was tilted to almost 90 °. Considering that the metal coordination complexes only form nanofilms, the difference in maintaining the bond strength of these membranes compared to the uncoated controls is significant and it is believed that improvements can be made by incorporating the metal coordination complexes more tightly (initimate) into the membrane and interface.

Claims

1. An electrically conductive interface of an electrode comprising an active material coated on an electrode substrate and a metal coordination complex in contact with the active material and the electrode substrate through a coordination bond, wherein:

(i) the electrode substrate is a current collector substrate selected from the group consisting of aluminum, copper, silver, and gold;

(ii) the active material is a first active material and/or a second active material, wherein the first active material and the second active material are independently selected from the group consisting of: metals, metal oxides, ceramics, intermetallics, metalloids, carbon, silicon, including oxides, alloys and composites thereof, and mixed metal oxides;

(iii) The metal ion of the metal coordination complex is selected from the group consisting of: chromium, ruthenium, iron, cobalt, aluminum, zirconium, and rhodium ions; and

wherein the active material comprises a binder and wherein when the active material further comprises both silicon nanopowder and conductive carbon black and the current collector substrate is copper foil, the binder is not poly (acrylic acid) (PAA).

2. A method of making an electrode comprising a conductive interface, the method comprising the steps of:

(i) providing an electrode substrate and an active material;

wherein the electrode substrate is a current collector substrate selected from the group consisting of aluminum, copper, silver, and gold; and is

The active material is a first active material and/or a second active material, wherein the first active material and the second active material are independently selected from the group consisting of: metals, metal oxides, ceramics, intermetallics, metalloids, carbon, silicon, including oxides, alloys and composites thereof, and mixed metal oxides;

(ii) contacting one or both of the current collector substrate and the active material with a metal coordination complex;

wherein the metal ion of the metal coordination complex is selected from the group consisting of: chromium, ruthenium, iron, cobalt, aluminum, zirconium, and rhodium ions; and

(iii) Coating the current collector substrate with the active material, thereby forming an electrode,

wherein the metal coordination complex is in contact with the active material and the current collector substrate through a coordination bond;

wherein the active material further comprises a binder and wherein when the active material further comprises both silicon nanopowder and conductive carbon black and the current collector substrate is copper foil, the binder is not poly (acrylic acid) (PAA).

3. The conductive interface of claim 1 or the method of claim 2, wherein the current collector substrate is a copper current collector substrate when the electrode is an anode.

4. The conductive interface of claim 1 or the method of claim 2, wherein the current collector substrate is an aluminum current collector substrate when the electrode is a cathode.

5. The conductive interface of claim 1 or the method of claim 2, wherein the active material is selected from the group consisting of silicon, mixed metal oxides, and carbon.

6. The conductive interface or method of claim 5, wherein the carbon is in a form selected from the group consisting of: graphite, super-P carbon, graphene, carbon nanotubes, carbon nanofibers, acetylene black, and Ketjen Black (KB).

7. The conductive interface or method of claim 5, wherein the mixed metal oxide includes one or more of cobalt, lithium, nickel, iron, and manganese.

8. The conductive interface of claim 1 or the method of claim 2, wherein the metal ion of the metal coordination complex is a chromium ion.

9. The conductive interface or method of claim 8, wherein the chromium ions are chromium (III) ions.

10. The conductive interface of claim 1 or the method of claim 2, wherein the metal coordination complex comprises a dative bond forming atom selected from nitrogen, oxygen, or sulfur that forms a dative bond with the metal ion.

11. The conductive interface of claim 1 or the method of claim 2, wherein the metal coordination complex is an oligomeric metal coordination complex.

12. The conductive interface of claim 1 or the method of claim 2, wherein the metal coordination complex is a hypopolyoxy-bridged chromium (III) complex.

13. The conductive interface of claim 1 or the method of claim 2, wherein the adhesive is selected from the group consisting of: polyvinylpyrrolidone, carboxymethylcellulose, polyacrylic acid (PAA), poly (methacrylic acid), maleic anhydride copolymers including poly (ethylene and maleic anhydride) copolymers, polyvinyl alcohol, carboxymethyl chitosan, natural polysaccharides, xanthan gum, alginates, and polyimides.

14. The conductive interface of claim 1 or the method of claim 2, wherein when the active material comprises both silicon nanopowder and conductive carbon black, then the current collector substrate is not a copper foil.