DE102011109137A1 - Lithium-ion battery, useful for operating plug in hybrid vehicle, comprises a positive electrode, a negative electrode and a separator, where the positive and negative electrodes comprise an electrode material containing an active material - Google Patents

Abstract

The lithium-ion battery comprises a positive electrode, a negative electrode, and a separator. The positive electrode and the negative electrode comprise an electrode material, which contains active material used for the first time in an electrochemical cell and a proportion of recycled active material. The active material is selected from a material, which absorbs or emits lithium ions or lithium. The recycled active material differs from the active material in terms of stoichiometry, structure or particle size. The lithium-ion battery comprises a positive electrode, a negative electrode, and a separator. The positive electrode and the negative electrode comprise an electrode material, which contains active material used for the first time in an electrochemical cell and a proportion of recycled active material. The active material absorbs or emits lithium ions or lithium. The recycled active material differs from the active material in terms of stoichiometry, structure or particle size. The recycled active material is present in the form of nanoparticles. A conductivity of the lithium-ion battery with the recycled active material is increased with respect to a similar lithium-ion battery with a corresponding additional proportion of the active material used for first time in the electrochemical cell. The nanoparticles (0.01-5 wt.%) are introduced in the electrode material of the positive electrode and/or the negative electrode. The total amount of nanoparticles and the electrode material are 100 wt.%, and the positive electrode contains nanoparticle (5-30 wt.%) together with the active material. The negative electrode contains nanoparticle (5-45 wt.%) together with the active material. The recycled active material is present in the positive electrode, and has an olivine structure or a spinel structure. An independent claim is included for a process for producing a lithium-ion battery.

Description

The invention relates to a lithium-ion battery containing recycled electrode material. The invention further relates to a method of manufacturing the battery, its use and the use of the recycled electrode material.

Lithium ion batteries can contain a variety of components such as chromium-nickel steel, lithium compounds, copper and aluminum and electrolytes. Some of these materials are recyclables and are therefore recycled. Corresponding recycling processes are known in principle from the prior art. These provide for disassembling the deactivated batteries into their components by means of mechanical separation, milling and classification methods. Subsequently, electrode material can be recycled and used to make new electrodes for lithium-ion batteries.

It has been proposed to convert recycled electrode material, which is to be used for producing new electrodes for lithium ion batteries, into nanopowders according to the principle of ultrasound spray electrolysis, wherein the particles can also be coated with carbon to improve the electrical conductivity ( SciTechs extra 2/2009, page 14 ).

An object of the present invention was to provide a lithium ion battery using recycled electrode material, and to provide a method of manufacturing the battery.

This object has been achieved with a lithium ion battery according to claim 1 and a method for producing the battery according to claim 13. Advantageous developments are described in the dependent claims.

• • eine positive Elektrode;
• • eine negative Elektrode;
• • einen Separator;

dadurch gekennzeichnet, dass
die positive Elektrode und die negative Elektrode oder die positive Elektrode oder die negative Elektrode ein Elektrodenmaterial aufweist/aufweisen, das erstmals in einer elektrochemischen Zelle eingesetztes Aktivmaterial sowie einen Anteil an recyceltem Aktivmaterial enthält, wobei das Aktivmaterial aus einem Material ausgewählt wird, welches Lithiumionen oder Lithium aufnehmen oder abgeben kann, und wobei das recycelte Aktivmaterial sich vom erstmals in einer elektrochemischen Zelle eingesetzten Aktivmaterial in mindestens einer der folgenden Eigenschaften unterscheidet: Stöchiometrie oder Struktur oder Teilchengröße.According to a first aspect of the invention, this relates to a lithium ion battery, comprising at least:

• • a positive electrode;
• • a negative electrode;
• • a separator;

characterized in that
the positive electrode and the negative electrode or the positive electrode or the negative electrode comprises an electrode material containing first active material used in an electrochemical cell and a content of recycled active material, wherein the active material is selected from a material comprising lithium ions or lithium and wherein the recycled active material differs from the first active material used in an electrochemical cell in at least one of the following properties: stoichiometry or structure or particle size.

battery

Hereinafter, the terms "lithium ion battery" and "lithium ion secondary battery" are used interchangeably. The terms also include the terms "lithium battery", "lithium ion secondary battery" and "lithium ion cell". A lithium-ion battery generally consists of a serial or series connection of individual lithium-ion cells. This means that the term "lithium ion battery" is used as a generic term for the terms used in the prior art and means both rechargeable batteries (secondary batteries) as well as non-rechargeable batteries (primary batteries).

electrodes

The term "positive electrode" in the following means the electrode which is able to pick up electrons when the battery is connected to a consumer, for example to an electric motor. It then represents the cathode.

The term "negative electrode" in the following means the electrode which, in use, is capable of giving off electrons. It then represents the anode.

The term "electrode material" below means inorganic material or inorganic compounds or substances used for or in or on an electrode or as an electrode.

These are preferably compounds or substances which under the working conditions of the lithium ion battery can absorb (intercalate) and also release lithium ions or metallic lithium due to their chemical nature. In the prior art, such material is also referred to as "active material" for the electrode. This material is preferably applied to a carrier for use in the battery, preferably a metallic carrier, preferably aluminum or copper.

Positive electrode

As the electrode material for the positive electrode, lithium phosphates of the molecular formula LiXPO4 can be used, where X = Mn, Fe, Co or Ni, or combinations thereof.

Further suitable compounds are lithium manganate, lithium cobaltate, lithium nickelate, or mixtures of two or more of these oxides or their mixed oxides.

The positive electrode may also contain mixtures of two or more of said substances.

Negative electrode

The negative electrode may be made of a variety of materials known for use in a prior art lithium-ion battery. For example, the negative electrode may contain lithium metal or lithium in the form of an alloy, either in the form of a foil, a grid, or in the form of particles held together by a suitable binder.

The use of lithium metal oxides such as lithium titanium oxide is also possible.

Suitable materials for the negative electrode are also graphite, synthetic graphite, carbon black, mesocarbon, doped carbon, fullerenes. As electrode material for the negative electrode and niobium pentoxide, tin or tin alloys, titanium dioxide, tin dioxide, silicon can be used. Preferably, tin or tin alloys, titanium dioxide, tin dioxide, silicon are present in a matrix of carbon, e.g. B. in graphite.

The materials used for the positive as well as for the negative electrode are preferably held together by a binder holding these materials on the electrode. For example, polymeric binders can be used. As the binder, for example, polyvinylidene fluoride, polyethylene oxide, polyethylene, polypropylene, polytetrafluoroethylene, polyacrylate, ethylene (propylene-diene monomer) copolymer (EPDM), and mixtures and copolymers thereof can be used.

The term "recycled active material" in the following means that the active material used is an active material which has already been used at least once in an electrochemical cell and / or has undergone at least one separation and / or grinding and / or classification process. Preferably, a material is used which has already been applied once to a metallic support such as preferably aluminum or copper. The term also implies that the material, in addition to material capable of accepting or donating lithium ions or metallic lithium, may contain other materials derived from the recycling process, such as binders or inorganic substances used as the electrode material.

In one embodiment, this recycled active material originates from a battery which has already been used as a power source at least once, that is, in the case of a secondary battery, has been charged and / or discharged at least once.

The term "active material used for the first time in an electrochemical cell" in the following means that the active material used is an active material which has not yet been used in an electrochemical cell and has not been subjected to a separation and grinding and / or classification process, that is not once applied to a metallic support such as preferably aluminum or copper; or which does not originate from a battery which has already been used at least once as a power source, ie has been charged and / or discharged at least once in the case of a secondary battery. The term "active material used for the first time in an electrochemical cell" in the following means that this material is used for the first time as an active material in an electrode material for an electrode (quasi "brand new").

In one embodiment, the active material used for the first time in an electrochemical cell has hitherto only been subjected to at least one charge and / or discharge cycle for the purpose of conditioning.

In one embodiment, both the recycled and the first active material used in an electrochemical cell are selected from a material that can accept or donate lithium ions or metallic lithium.

The term "proportion" in the following means that the recycled active material is used in an amount of 0.1 to 99.9% by weight, preferably 0.1 to 60% by weight, more preferably 0.1 to 50% by weight. % may be present in addition to the first active material used in an electrochemical cell, wherein the total amount of recycled and used for the first time in an electrochemical cell active material is 100 wt .-%.

In one embodiment, the recycled active material differs from the first active material used in an electrochemical cell in at least one of the following properties: stoichiometry, structure or particle size, or in two or three of these properties.

The term "stoichiometry" in the following means the composition, preferably the chemical composition of the active material, ie the ratio of the chemical elements in the active material. This can be determined by elemental analysis.

The term "structure" in the following means the arrangement, preferably the spatial arrangement, of the chemical elements in the active material. This arrangement can be determined by an X-ray structure analysis. Examples of a structure are an arrangement of suitable elements in a spinel lattice or an olivering lattice or in a layer structure, for example an "O3" layer structure.

The term "particle size" in the following means the particle size of the particles constituting the recycled material or active material used for the first time in an electrochemical cell. The determination of the particle size can be carried out by known methods, for example by mechanical methods such as sieve analysis, or optical methods such as laser light scattering.

In one embodiment, the recycled active material differs from the active material used in an electrochemical cell for the first time in stoichiometry.

In another embodiment, the recycled active material differs from the active material used in an electrochemical cell for the first time in the structure.

In another embodiment, the recycled active material differs in particle size from the first active material used in an electrochemical cell.

In one embodiment, the recycled active material differs from the active material used in an electrochemical cell for the first time in stoichiometry and structure; or in stoichiometry and particle size; or in structure and particle size; or in stoichiometry and structure and particle size.

In one embodiment, this active material, and in particular the recycled active material, is converted into nanoparticles for the application according to the invention.

In one embodiment, the term "nanoparticles" means that these particles have a particle size measured as D95 value of less than 15 microns. Preferably, the particle size is less than 10 microns.

In a further embodiment, the particles have a particle size measured as D95 value between 0.005 μm to 10 μm, or a particle size measured as D95 value of less than 10 μm, the D50 value being 4 μm ± 2 μm and the D10 Value is less than 1.5 μm.

The values given are determined by measurement using static laser light scattering (laser diffraction, laser diffractometry). Such methods are known in the art.

Suitable methods for preparing such nanoparticles are known in the art.

In one embodiment, ultrasound spray pyrolysis may be used to prepare the nanoparticles ( SciTechs extra 2/2009, page 14 ). In Ultraschallsprühpyrolyse an ultrasonic nebulizer is used in which by electrostriction a crystal is excited to high-frequency vibrations. As a result, an aerosol containing the resulting nanoparticles can be produced from any solution of the starting compounds.

In another embodiment, a microwave plasma process may be used to prepare the nanoparticles. The starting compounds are vaporized and converted into a plasma with the aid of microwaves. As a reaction product nanoparticles are obtained. Usually, the particle sizes are well below 10 nm.

In a particularly preferred embodiment, the nanoparticles can be coated with other substances. This results in so-called "nanocomposite particles" or "core / shell particles". In a further preferred embodiment, the nanoparticles are coated with carbon.

For the purposes of the present invention, the recycled active material is used in combination with active material used for the first time in an electrochemical cell.

In one embodiment, the positive and / or negative electrode contains the nanoparticles obtained via the recycling process in a proportion of 0.01 to 5 wt .-% together with first used in an electrochemical cell active material, the total amount of nanoparticles and first time each used in an electrochemical cell active material is 100 wt .-%.

In one embodiment, the proportion is 0.05 to 4 wt .-%, or 0.1 to 3 wt .-%.

In another embodiment, the positive electrode contains the nanoparticles in an amount of 5 to 30 wt .-% together with the first used in an electrochemical cell active material, wherein the total amount of nanoparticles and first used in an electrochemical cell active material is 100 wt .-% ,

In one embodiment, the amount is 10 to 25 wt% or 15 to 20 wt%.

In a further embodiment, the negative electrode contains the nanoparticles in a proportion of 5 to 45 wt .-% together with first used in an electrochemical cell active material, wherein the total amount of nanoparticles and first used in an electrochemical cell active material is 100 wt .-% ,

In one embodiment, the proportion is 10 to 40 wt .-%, or 15 to 35 wt .-%, or 20 to 25 wt .-%.

According to the invention can be used as active material materials, such as are commonly used for cathodes.

In one embodiment, the recycled active material is introduced into an active material used for the first time in an electrochemical cell, which has a spinel structure or an olivine structure, or vice versa.

In one embodiment, the active material used for the first time in an electrochemical cell, into which the recycled material is introduced, has a spinel structure. It can lithium manganate, lithium cobaltate, lithium nickelate, or mixtures of two or more of these oxides or mixed oxides are used.

In one embodiment, the active material used for the first time in an electrochemical cell has an olivine structure of the molecular formula LiXPO4, where X = Mn, Fe, Co or Ni, or combinations thereof.

It is also possible to use mixtures of two or more of the substances mentioned.

Furthermore, it is also possible that the active material used for the first time in an electrochemical cell, into which the recycled material is introduced, contains carbon to increase the conductivity. Such particles can be prepared by known methods, for example by coating with carbon compounds such as acrylic acid or ethylene glycol. It is then pyrolyzed, for example at a temperature of 2,500 ° C.

In one embodiment, the recycled positive electrode active material is selected from the group consisting of lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, or a mixture of two or three of these oxides, or lithium manganese cobalt nickel mixed oxide. Preferably, the positive electrode active material used for the first time in an electrochemical cell is selected from the group consisting of: lithium iron phosphate, lithium manganese phosphate, or lithium cobalt phosphate, or a mixture of two or three of these phosphates.

In another embodiment, the recycled positive electrode active material is selected from the group consisting of: lithium iron phosphate, lithium manganese phosphate, lithium cobalt phosphate, or a mixture of two or three of these phosphates. Preferably, the positive electrode active material used for the first time in an electrochemical cell is selected from the group consisting of lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, or a mixture of two or three of these oxides, or lithium manganese cobalt nickel mixed oxide.

Surprisingly, it has been found that when using recycled lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, or a mixture of two or three of these oxides, or lithium-manganese-cobalt-nickel mixed oxide, in particular in the form of carbon-coated nanoparticles, when added to a first time used in an electrochemical cell active material with olivine structure, ie lithium iron phosphate, lithium manganese phosphate, lithium cobalt phosphate, or a mixture of two or three of these phosphates, the conductivity of the electrode can be increased by 10 to 15% based on an electrode, the only first in an electrochemical Cell has used active material.

Surprisingly, it has also been found that when using recycled lithium iron phosphate, lithium manganese phosphate, lithium cobalt phosphate, or a mixture of two or three of these phosphates, in particular in the form of carbon-coated nanoparticles, when added to an active material with spinel structure, for the first time used in an electrochemical cell Lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, or a mixture of two or three of these oxides, or lithium-manganese-cobalt-nickel mixed oxide, the conductivity of the electrode can be increased by 10 to 15% based on an electrode, the only first in a having active material used electrochemical cell.

In another embodiment, the recycled active material is selected from the group consisting of lithium titanium oxide, tin or tin alloys, silicon and carbon, or two or more of these elements or compounds, preferably lithium titanium oxide, silicon or tin. In this embodiment, the recycled active material is preferably used together with a first in a employed active material of the negative electrode, which is also selected from lithium titanium oxide, tin or tin alloys, silicon and carbon.

In one embodiment, the recycled active material is silicon or tin, and the first active material used in an electrochemical cell is carbon, for example in the form of graphite.

In one embodiment, the battery has a separator.

The term "separator" below means a material that separates the negative and the positive electrode of the lithium ion battery from each other.

The separator used for the battery must be permeable to lithium ions in order to ensure the ion transport of the lithium ions between the positive and the negative electrode. On the other hand, the separator must be insulating for electrons.

In one embodiment, the separator comprises a nonwoven web of nonwoven polymer fibers that are electrically nonconductive. Such nonwovens are produced in particular by spinning processes with subsequent solidification.

An embodiment of the lithium ion battery is characterized in that it comprises a separator comprising a nonwoven web of nonwoven polymer fibers coated on one or both sides with an inorganic material.

The term "nonwoven" is used synonymously with terms such as "nonwoven fabrics", "knits" or "felt". Instead of the term "unwoven" the term "not woven" is used.

Preferably, the polymer fibers are selected from the group of polymers consisting of polyacrylonitrile, polyolefin, polyester, polyimide, polyetherimide, polysulfone, polyamide, polyether. Suitable polyolefins are, for example, polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride. Preferred polyesters are polyethylene terephthalates.

For the purposes of the present invention, the nonwoven contained in the separator is preferably coated on one or both sides with an ion-conducting inorganic material. The term "coating" also includes below that the ion-conducting inorganic material can be located not only on one side or both sides of the nonwoven, but also within the nonwoven.

The ion-conductive inorganic material is ion-conducting in a temperature range of -40 ° C to 200 ° C, i. H. ion-conducting for lithium ions. The material used for the coating is at least one compound from the group of oxides, phosphates, sulfates, titanates, silicates, aluminosilicates at least one of zirconium, aluminum, silicon or lithium.

In a preferred embodiment, the ion-conducting material comprises or consists of alumina or zirconia or alumina and zirconia.

In one embodiment, a separator is used in the battery according to the invention, which consists of an at least partially permeable carrier, which is not or only poorly electron-conducting. This support is coated on at least one side with an inorganic material. As at least partially permeable carrier an organic material is used, which is designed as a non-woven fleece. The organic material is in the form of polymer fibers, preferably polymer fibers of polyethylene terephthalate (PET). The nonwoven fabric is coated with an inorganic ion conducting material which is preferably ion conducting in a temperature range of -40 ° C to 200 ° C. The inorganic ion-conducting material preferably has at least one compound from the group of oxides, phosphates, sulfates, titanates, silicates, aluminosilicates with at least one of the elements zirconium, aluminum, lithium, particularly preferably zirconium oxide. The inorganic ion-conducting material preferably has particles with a maximum diameter of less than 100 nm.

Such a separator is marketed in Germany, for example, under the trade name "Separion ^®" by the company Evonik AG. Methods for producing such separators are known from the prior art, for example from the EP 1 017 476 B1 . WO 2004/021477 and WO 2004/021499 ,

In the following, particularly preferred embodiments of the separator used in the battery according to the invention as well as advantages of the battery will be summarized, in particular with regard to safety aspects.

In principle, too large pores and holes in separators used in secondary batteries can lead to an internal short circuit. The battery can then discharge itself very quickly in a dangerous reaction. In this case, such large electrical currents can occur that a closed battery cell can even explode in the worst case. For this reason, the Separator contribute significantly to the safety or lack of security of a lithium high-performance or Lithiumhochenergie battery.

Polymer separators prevent i. A. from a certain temperature (the so-called "shut-down temperature", which is typically about 120 ° C) any current transport through the electrolyte. This happens because at this temperature, the pore structure of the separator collapses and all pores are closed. The fact that no ions can be transported, the dangerous reaction that can lead to an explosion, comes to a standstill. However, if the cell continues to be heated due to external circumstances, the so-called "break-down temperature" is exceeded at approx. 150 to 180 ° C. From this temperature it comes in conventional separators to melt the separator, which contracts. In many places in the battery cell, there is now a direct contact between the two electrodes and thus to a large internal short circuit. This leads to an uncontrolled reaction, which can end with an explosion of the cell, or the resulting pressure must be reduced by a pressure relief valve (a rupture disk) often under fire phenomena.

In the separator used in the battery according to the invention comprising a non-woven of nonwoven polymer fibers and the inorganic coating, it can only come to shut-down (shutdown), when the polymer melted by the high temperature of the carrier material and penetrates into the pores of the inorganic material and this thereby closing. On the other hand, there is no such break-down (collapse) as the inorganic particles ensure that complete melting of the separator can not occur. This ensures that there are no operating states in which a large-area short circuit can occur. By the type of nonwoven used, which has a particularly suitable combination of thickness and porosity, separators can be produced that can meet the requirements for separators in high-performance batteries, especially lithium high-performance batteries. By the simultaneous use of precisely matched in their particle size oxide particles for the preparation of the porous (ceramic) coating a particularly high porosity of the finished separator is achieved, the pores are still small enough to unwanted growth of "lithium whiskers" through to prevent the separator.

Due to the high porosity in conjunction with the small thickness of the separator, it is also possible to impregnate the separator completely or at least almost completely with the electrolyte, so that no dead spaces in individual areas of the separator and thus in certain windings or laminations of the battery cells may arise in which there is no electrolyte. This is achieved in particular by the compliance of the particle size of the oxide particles, the resulting separators are free or virtually free of closed pores, in which the electrolyte can not penetrate. The separators used for the invention also have the advantage that partially attach to the inorganic surfaces of the separator material, the anions of the conducting salt, which leads to an improvement in the dissociation and thus to a better ionic conductivity in the high current range. Another not inconsiderable advantage of the separator is the very good wettability. Due to the hydrophilic ceramic coating, wetting with electrolytes takes place very rapidly, which likewise leads to improved conductivity.

The separator used for the battery according to the invention, comprising a flexible nonwoven with a porous inorganic coating on and in this nonwoven, the material of the nonwoven being selected from nonwoven, non-electrically conductive polymer fibers, is also characterized in that the nonwoven fabric has a thickness of less than 30 microns, a porosity of more than 50%, preferably from 50 to 97% and a pore radius distribution, wherein at least 50% of the pores have a pore radius of 75 to 150 microns.

Particularly preferably, the separator has a nonwoven, which has a thickness of 5 to 30 microns, preferably a thickness of 10 to 20 microns. Also particularly important is a homogeneous distribution of pore radii in the web as indicated above. An even more homogeneous pore radius distribution in the nonwoven, in combination with optimally matched oxide particles of a certain size, leads to an optimized porosity of the separator. The thickness of the substrate has a great influence on the properties of the separator, since on the one hand the flexibility but also the sheet resistance of the electrolyte-impregnated separator depends on the thickness of the substrate. Due to the small thickness, a particularly low electrical resistance of the separator is achieved in the application with an electrolyte. The separator itself has a very high electrical resistance, since it itself must have insulating properties. In addition, thinner separators allow increased packing density in a battery pack so that one can store a larger amount of energy in the same volume.

Preferably, the web has a porosity of 60 to 90%, more preferably from 70 to 90%. The porosity is defined as the volume of the web (100%) minus the volume of the fibers of the fleece, ie the proportion of the volume of the fleece that is not filled by material.

The volume of the fleece can be calculated from the dimensions of the fleece. The volume of the fibers results from the measured weight of the fleece considered and the density of the polymer fibers. The large porosity of the substrate also allows a higher porosity of the separator, which is why a higher uptake of electrolytes with the separator can be achieved. In order to obtain a separator having insulating properties, it has as polymer fibers for the non-woven fabric preferably non-electrically conductive fibers of polymers as defined above, which are preferably selected from polyacrylonitrile (PAN), polyesters such. As polyethylene terephthalate (PET) and / or polyolefin (PO), such as. As polypropylene (PP) or polyethylene (PE), or mixtures of such polyolefins.

The polymer fibers of the nonwovens preferably have a diameter of from 0.1 to 10 .mu.m, more preferably from 1 to 4 .mu.m.

Particularly preferred flexible nonwovens have a basis weight of less than 20 g / m ² , preferably from 5 to 10 g / m ² .

Preferably, the nonwoven is flexible and has a thickness of less than 30 microns.

The separator has a porous, electrically insulating, ceramic coating on and in the fleece. The porous inorganic coating on and in the nonwoven preferably has oxide particles of the elements Li, Al, Si and / or Zr with an average particle size of 0.5 to 7 μm, preferably of 1 to 5 μm and very particularly preferably of 1 , 5 to 3 microns on.

Particularly preferably, the separator has a porous inorganic coating on and in the nonwoven, which has aluminum oxide particles. Preferably, these have an average particle size of 0.5 to 7 microns, preferably from 1 to 5 microns and most preferably from 1.5 to 3 microns. In one embodiment, the alumina particles are bonded to an oxide of the elements Zr or Si.

In order to achieve the highest possible porosity, preferably more than 50% by weight and more preferably more than 80% by weight of all particles are within the abovementioned limits of average particle size. As already described above, the maximum particle size is preferably 1/3 to 1/5 and particularly preferably less than or equal to 1/10 of the thickness of the nonwoven used.

The separator preferably has a porosity of from 30 to 80%, preferably from 40 to 75% and particularly preferably from 45 to 70%. The porosity refers to the achievable, ie open pores. The porosity can be determined by the known method of mercury porosimetry or can be calculated from the volume and density of the starting materials used, if it is assumed that only open pores are present. The separators used for the battery according to the invention are also distinguished by the fact that they can have a tensile strength of at least 1 N / cm, preferably of at least 3 N / cm and very particularly preferably of 3 to 10 N / cm. The separators can preferably be bent without damage to any radius down to 100 mm, preferably down to 50 mm and most preferably down to 1 mm.

The high tensile strength and the good bendability of the separator have the advantage that changes in the geometries of the electrodes occurring during the charging and discharging of a battery can be through the separator without being damaged. The flexibility also has the advantage that commercially standardized winding cells can be produced with this separator. In these cells, the electrode / separator layers are spirally wound together in a standardized size and contacted. In one embodiment, it is possible to design the separator to have the shape of a concave or convex sponge or pad, or the shape of wires or a felt. This embodiment is well suited to compensate for volume changes in the battery. Corresponding preparation methods are known to the person skilled in the art.

In a further embodiment, the polymer fleece used in the separator has a further polymer. Preferably, this polymer is disposed between the separator and the negative electrode and / or the separator and the positive electrode, preferably in the form of a polymer layer.

In one embodiment, the separator is coated with this polymer on one or both sides.

Said polymer may be in the form of a porous membrane, i. H. as a film, or in the form of a nonwoven, preferably in the form of a nonwoven fabric of non-woven polymer fibers.

These polymers are preferably selected from the group consisting of polyester, polyolefin, polyacrylonitrile, polycarbonate, polysulfone, Polyethersulfone, polyvinylidene fluoride, polystyrene, polyetherimide.

Preferably, the further polymer is a polyolefin. Preferred polyolefins are polyethylene and polypropylene.

The separator is preferably coated with one or more layers of the further polymer, preferably of the polyolefin, which is preferably also present as a nonwoven, that is to say as nonwoven polymer fibers.

Preferably, a non-woven of polyethylene terephthalate is used in the separator, which is coated with one or more layers of the further polymer, preferably of the polyolefin, which is preferably also present as non-woven, so as non-woven polymer fibers.

Particular preference is given to a separator of the above-described type of separation which is coated with one or more layers of the further polymer, preferably of the polyolefin, which is preferably likewise present as a nonwoven, that is to say as nonwoven polymer fibers.

The coating with the further polymer, preferably with the polyolefin, can be achieved by gluing, lamination, by a chemical reaction, by welding or by a mechanical connection. Such polymer composites and processes for their preparation are known from EP 1 852 926 known.

The fiber diameters of the polyethylene terephthalate fleece are preferably larger than the fiber diameters of the further polymer fleece, preferably the polyolefin fleece, with which the separator is coated on one or both sides.

Preferably, the nonwoven made of polyethylene terephthalate then has a higher pore diameter than the nonwoven, which is made of the other polymer.

Preferably, the nonwovens usable in the separator are made of nanofibers of the polymers used, whereby nonwovens are formed which have a high porosity with formation of small pore diameters. Thus, both the risk of short-circuit reactions can be further reduced.

The use of a polyolefin in addition to the polyethylene terephthalate ensures increased safety of the electrochemical cell, since in unwanted or excessive heating of the cell, the pores of the polyolefin contract and the charge transport through the separator is reduced or terminated. Should the temperature of the electrochemical cell increase to such an extent that the polyolefin begins to melt, the polyethylene terephthalate effectively counteracts the melting together of the separator and thus an uncontrolled destruction of the electrochemical cell.

The use of a separator of the type described above is important because due to the increased conductivity of the electrodes in the battery according to the invention the formation of whiskers can be effectively counteracted and the risk of melt through of the separator or the formation of short circuits can be minimized.

In another embodiment, the lithium-ion battery comprises a nonaqueous electrolyte.

The term "electrolyte" in the following preferably means a liquid and a conductive salt. Preferably, the liquid is a solvent for the conducting salt. Preferably, the electrolyte is then present as an electrolyte solution. Suitable electrolytes are known in the art.

Suitable solvents are preferably inert. Suitable solvents are preferably solvents such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butyl methyl carbonate, ethyl propyl carbonate, dipropyl carbonate, cyclopentanones, sulfolanes, dimethylsulfoxide, 3-methyl-1,3-oxazolidine-2-one, γ-butyrolactone, 1,2-diethoxymethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, methyl acetate, ethyl acetate, nitromethane, 1,3-propanesultone.

In one embodiment, ionic liquids may also be used as the solvent.

Ionic liquids are known in the art. They contain only ions. Examples of useful cations which may in particular be alkylated are imidazolium, pyridinium, pyrrolidinium, guanidinium, uronium, thiuronium, piperidinium, morpholinium, sulfonium, ammonium and phosphonium cations. Examples of useful anions are halide, tetrafluoroborate, trifluoroacetate, triflate, hexafluorophosphate, phosphinate and tosylate anions.

Examples of ionic liquids which may be mentioned are: N-methyl-N-propylpiperidinium bis (trifluoromethylsulfonyl) imide, N-methyl-N-butyl-pyrrolidinium bis (trifluoromethylsulfonyl) imide, N-butyl-N-trimethyl-ammonium bis (trifluoromethylsulfonyl) imide, triethylsulfonium bis (trifluoromethylsulfonyl) imide, N, N- Diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethylsulfonyl) imide.

Two or more of the above liquids can be used.

Preferred conductive salts are lithium salts which have inert anions and which are non-toxic. Suitable lithium salts are preferably lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium bis (trifluoromethylsulfonyl imide), lithium trifluoromethanesulfonate, lithium tris (trifluoromethylsulfonyl) methide, lithium tetrafluoroborate, lithium perchlorate, lithium tetrachloroaluminate, lithium bisoxalatoborate, lithium difluorooxalatoborate and / or lithium chloride; and mixtures of one or more of these salts.

• (i) Überführen eines recycelten Aktivmaterials einer Elektrode einer Lithiumionen-Batterie in Nanopartikel;
• (ii) Einbringen der Nanopartikel aus Stufe (i) in ein erstmals in einer elektrochemischen Zelle eingesetztes Aktivmaterial für die positive Elektrode und die negative Elektrode oder für die positive Elektrode oder die negative Elektrode der Lithiumionen-Batterie.

According to a second aspect of the invention, it relates to a method for producing a lithium ion battery according to the invention, which comprises the steps (i) and (ii):

• (i) transferring a recycled active material of an electrode of a lithium ion battery into nanoparticles;
• (ii) introducing the nanoparticles of step (i) into a positive electrode and negative electrode active material or first positive electrode or negative electrode of the lithium ion battery used in an electrochemical cell.

The introduction of the nanoparticles into an electrode material of step (ii) can be carried out by known methods.

In one embodiment, the nanoparticles of the recycled active material are processed into an aqueous suspension with further components of the electrode material, for example the spinels or olivines as explained above. This can be prepared by the methods customary in ceramic technology, for example by mixing the components used, preferably by mixing or by stirring the components. The mixing can also be supported by sonication.

The term "suspension" is used interchangeably below with the terms "emulsion", "dispersion", "colloid" or "slurry". Preferably, the suspension is an aqueous suspension.

It is possible to use organic solvents, preferably ethanol, isopropanol, acetone or dimethylformamide, or mixtures of these solvents in the suspension.

In one embodiment, the suspension may also contain binders which promote adhesion of the nanoparticles and the other components on the metallic support of the electrode. Suitable binders are known in the art. Preferably, polymeric binders can be used, preferably polyvinylidene fluoride, polyethylene oxide, polyethylene, polypropylene, polytetrafluoroethylene, polyacrylate, ethylene (propylene-diene monomer) copolymer (EPDM) and blends and copolymers thereof.

The suspension may be applied by known methods to the metallic support used in the electrode, preferably by extrusion or calendering methods. After drying, the electrode is obtained.

According to a third aspect of the invention, this relates to the use of a lithium-ion battery according to the invention or a lithium-ion battery produced by the method according to the invention for operating a hybrid vehicle or a plug-in hybrid vehicle.

The term "hybrid vehicle" in the sense of the invention means a vehicle which has an electric drive as well as an internal combustion engine. The battery required for the electric drive is charged after or during discharge via energy from the internal combustion engine.

The term "plug in hybrid vehicle" in the sense of the invention means a vehicle which has an electric drive as well as an internal combustion engine, wherein the battery required for the electric drive can be externally charged after or during discharge.

According to a fourth aspect of the invention, it relates to the use of nanoparticles obtained by converting a recycled active material, preferably a recycled active material of an electrode of a lithium ion battery, into nanoparticles, wherein the nanoparticles are carbon coated, in or as a conductive ink or in one or more as a primer or in an electrode or as an active material of an electrode.

The nanoparticles according to these uses are prepared as described in the first aspect of the invention.

The term "conductive ink" in the context of the invention means an electrically conductive lacquer.

In one embodiment, the nanoparticles are embedded in a binder. The binder component may comprise a solvent and a synthetic resin in one embodiment. suitable Solvents and synthetic resins are known from conductive ink technology. With the help of conductive paints, for example, defective conductor tracks can be repaired in electronic devices.

The term "primer" in the context of the invention means a primer or an adhesion promoter.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1017476 B1 [0071]
• WO 2004/021477 [0071]
• WO 2004/021499 [0071]
• EP 1852926 [0097]

Cited non-patent literature

• SciTechs Extra 2/2009, page 14 [0003]
• SciTechs extra 2/2009, page 14 [0038]

Claims (15)

Lithium ion battery, comprising at least: a positive electrode; a negative electrode; a separator; characterized in that the positive electrode and the negative electrode or the positive electrode or the negative electrode comprises an electrode material containing first active material used in an electrochemical cell and a content of recycled active material, wherein the active material is selected from a material, which can accept or donate lithium ions or lithium, and wherein the recycled active material differs from the active material first used in an electrochemical cell in at least one of the following properties: stoichiometry or structure or particle size. The lithium-ion battery according to claim 1, wherein the recycled active material is different from the active material in stoichiometry first used in an electrochemical cell. A lithium ion battery according to claim 1 or 2, wherein the recycled active material is different from the active material used in an electrochemical cell for the first time in the structure. A lithium ion battery according to any one of the preceding claims, wherein the recycled active material is different in particle size from the active material used for the first time in an electrochemical cell. A lithium-ion battery according to any one of the preceding claims, wherein the recycled active material is in the form of nanoparticles. The lithium ion battery of claim 5, wherein the nanoparticles are carbon coated. Lithium ion battery according to one of the preceding claims, wherein the conductivity of the lithium ion battery is increased with recycled active material compared to an otherwise identical lithium ion battery with a corresponding additional proportion of active material used for the first time in an electrochemical cell. Lithium ion battery according to claim 5 or 6, wherein the nanoparticles are introduced in a proportion of 0.01 to 5 wt .-% in the first used in an electrochemical cell electrode material of the positive electrode and / or the negative electrode, the total amount of Nanoparticles and electrode material introduced for the first time in an electrochemical cell is in each case 100 wt .-%, or wherein the positive electrode contains nanoparticles in an amount of 5 to 30 wt .-% together with first used in an electrochemical cell active material, wherein the total amount of nanoparticles and 100% by weight of active material used in an electrochemical cell for the first time. Lithium ion battery according to claim 5 or 6, wherein the negative electrode nanoparticles in an amount of 5 to 45 wt .-% together with first used in an electrochemical cell active material, wherein the total amount of nanoparticles and first used in an electrochemical cell active material 100th Wt .-% is. A lithium ion battery according to any one of the preceding claims, wherein the recycled active material is in a positive electrode having an active material having an olivine structure or a spinel structure first used in an electrochemical cell. The lithium ion battery of claim 10, wherein the recycled active material is selected from the group consisting of: lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, or a mixture of two or three of these oxides, or lithium manganese cobalt nickel mixed oxide, and the first in a active material used in the electrochemical cell is selected from the group comprising: lithium iron phosphate, lithium manganese phosphate, or lithium cobalt phosphate, or a mixture of two or three of these phosphates; or wherein the recycled active material is selected from the group comprising: lithium iron phosphate, lithium manganese phosphate, lithium cobalt phosphate, or a mixture of two or three of these phosphates, and the first active material used in an electrochemical cell is selected from the group consisting of lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, or a mixture of two or three of these oxides, or lithium-manganese-cobalt-nickel mixed oxide. The lithium ion battery according to any one of the preceding claims, wherein the recycled negative electrode active material is selected from the group consisting of: lithium titanium oxide, tin or tin alloys, silicon and carbon, or two or more of these elements or compounds, and for the first time in an electrochemical cell used active material is selected from the same group. A method of manufacturing a lithium ion battery according to any one of claims 5 to 12, comprising steps (i) and (ii): (i) transferring a recycled active material of an electrode of a lithium ion battery to nanoparticles; (ii) introducing the nanoparticles of step (i) into a positive electrode and negative electrode active material or first positive electrode or negative electrode of the lithium ion battery used in an electrochemical cell. Use of a lithium ion battery according to any one of claims 1 to 12, or a lithium ion battery manufactured according to claim 13, for operating a hybrid vehicle or a plug in hybrid vehicle. Use of nanoparticles obtained by converting a recycled active material of an electrode into nanoparticles, wherein the nanoparticles are coated with carbon, as a conductive ink or as a primer or as an active material for an electrode.