HK1165101B - Multiple electrolyte electrochemical cells - Google Patents

Abstract

Electrode assemblies for use in electrochemical cells are provided. The negative electrode assembly comprises negative electrode active material and an electrolyte chosen specifically for its useful properties in the negative electrode. These properties include reductive stability and ability to accommodate expansion and contraction of the negative electrode active material. Similarly, the positive electrode assembly comprises positive electrode active material and an electrolyte chosen specifically for its useful properties in the positive electrode. These properties include oxidative stability and the ability to prevent dissolution of transition metals used in the positive electrode active material. A third electrolyte can be used as separator between the negative electrode and the positive electrode.

Description

Multi-electrolyte electrochemical cell

Cross Reference to Related Applications

Priority of U.S. provisional patent application 61/028,443 (converted to international application PCT/US09/34156) filed on 13/2008, month 2, year 2008, U.S. provisional patent application 61/046,685 (converted to international application PCT/US09/41180) filed on 21/2008, month 4, year 2008, and U.S. provisional patent application 61/112,605 filed on 7/11, year 2008, are claimed for this application, the entire contents of which are incorporated herein by reference.

This application is related to the priority of pending U.S. provisional patent application 61/112596 entitled METHOD OFFORMING AN ELECTRODE ASSEMBLY filed on 7.11.2008 AND U.S. provisional patent application 61/112592 filed on 7.11.2008 AND entitled ELECTRODES WITHSOLID POLYMER ELECTROLYTESS AND REDUCED POROSITY, both of which are incorporated herein by reference.

Technical Field

The present invention relates generally to lithium batteries, and more particularly to the use of various electrolytes in such lithium batteries to optimize their performance.

Background

For use in batteries, the electrolyte is chemically compatible/stable with the anode and cathode materials. In addition, the electrolyte is electrochemically stable, i.e., the electrolyte is stable with respect to reduction at the anode and oxidation at the cathode when the cell is at potential. These requirements are particularly difficult to meet in lithium batteries due to the extreme reactivity of lithium itself. When a liquid electrolyte is used, the electrolyte permeates the anode and cathode and the separator, and therefore one electrolyte must meet all standards. Since the best electrolyte for the anode and the best electrolyte for the cathode may not be the same, some compromise must be made in selecting the electrolyte.

Thus, there is a clear need for a battery cell design in which different parts of the cell may contain different electrolytes, each optimized for its specific function, but all function together without compromising the overall operation of the cell.

Drawings

The above and other aspects of the present invention will be readily apparent to those skilled in the art from the following exemplary embodiments, taken in conjunction with the accompanying drawings.

FIG. 1 is an exemplary illustration of various negative pole assemblies according to embodiments of the invention.

Fig. 2 is an exemplary illustration of various positive electrode assemblies according to embodiments of the invention.

Fig. 3 is an exemplary illustration of an electrochemical cell according to an embodiment of the present invention.

FIG. 4 is a schematic representation of a diblock copolymer and the structures of regions it may form according to embodiments of the invention.

FIG. 5 is a schematic representation of a triblock copolymer and the domain structures that it can form according to an embodiment of the present invention.

FIG. 6 is a schematic representation of a triblock copolymer and the domain structures that it can form according to another embodiment of the present invention.

Fig. 7 shows a complex impedance plot for a single electrolyte system (X) and a dual electrolyte system (O).

Fig. 8A and 8B show specific capacity data during 500 cycles of a battery comprising one dry polymer electrolyte and 100 cycles of a dual electrolyte battery, respectively.

Disclosure of Invention

Preferred embodiments are described in the context of an electrolyte in an electrochemical cell. However, one skilled in the art will readily appreciate that the materials and methods disclosed herein have application in a wide variety of other contexts where it is important to optimize the electrochemical interaction between the electrolyte and the electrochemically active material. These electrolytes can be used in electrochemical devices such as capacitors, electrochemical/capacitive memories, electrochemical (e.g., dye sensitized) solar cells, and electrochromic devices.

These and other objects and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.

In the present disclosure, the terms "negative electrode" and "anode" are both used to refer to "negative electrode". Likewise, the terms "positive electrode" and "cathode" are both used to refer to the "positive electrode".

In the present disclosure, the term "dry polymer" is used to refer to a polymer having a long chain that is not plasticized by any small molecule. The dry polymer is free of organic solvents or plasticizers.

Although not always explicitly mentioned, it is understood that the electrolytes described herein include metal salts, such as lithium salts, to ensure that they are ionically conductive. Non-lithium salts such as other alkali metal or aluminium salts, sodium or magnesium salts may also be used.

An electrochemical cell has a negative electrode assembly and a positive electrode assembly with an ion-conducting separator (separator) therebetween. In one embodiment of the present invention, the negative electrode assembly comprises at least a negative electrode active material and an electrolyte specifically selected for use with the negative electrode active material (referred to herein as NE (negative electrode) electrolyte).

Fig. 1 illustrates various exemplary arrangements of the negative active material (black area) and NE electrolyte (gray area). The anode active material may be provided as particles (fig. 1a-1d, 1f) or as a film or foil (fig. 1 e). The negative electrode assembly may be formed by combining negative electrode active material particles with an NE electrolyte to form a composite layer (fig. 1a-1 d). In some arrangements, other materials (not shown) may be added to the composite layer to enhance, for example, electronic and ionic conductivity. In some arrangements, the composite is porous, i.e. comprises pores, shown as white voids in fig. 1b, 1 d; in other arrangements, the composite is non-porous (fig. 1a, 1 c). In still other arrangements, the NE dry polymer electrolytes shown in fig. 1e and 1f may also contain pores. In a negative electrode assembly having a composite layer, the NE dry polymer electrolyte may be entirely contained in the composite layer (fig. 1a, 1 b). In another arrangement, adjacent composite layers may have additional thin layers of NE dry polymer electrolyte (fig. 1c, 1 d). In some arrangements, the current collector (white layer defined by dashed lines in the figure) is also part of the negative electrode assembly.

In arrangements where the negative active material is a film or foil, the negative electrode assembly comprises at least a film or foil as shown in fig. 1e and an NE electrolyte layer adjacent to and in ionic contact with the film or foil. In some arrangements, the negative electrode material is not a solid thin film, but is arranged as an aggregate with the negative electrode active material particles in close contact with each other to ensure ionic and electronic communication between the particles (fig. 1 f). Such a structure can be produced, for example, by pressing and/or sintering anode active material particles. In some arrangements, other materials may be added to the layer of anode material particles, for example, to enhance electronic or ionic conductivity. In one arrangement, carbon particles are added to enhance the conductivity of the electrons. The negative electrode assembly includes at least a NE electrolyte layer in ionic communication with the layer of negative electrode active material particles. In some arrangements, there is also a current collector (shown as a white layer defined by dashed lines) in electrical contact with the negative electrode assembly.

The NE electrolyte is selected for use particularly with the negative active material. In one embodiment of the invention, the NE electrolyte is a dry polymer (polymer with long chains that is not plasticized by any small molecules) electrolyte. The NE electrolyte is electrochemically stable with respect to the negative active material. That is, the NE electrolyte is stable to reduction and resistant to chemical and electrochemical reactions that would result in the NE electrolyte being reduced at the interface with the anode material. The range of potentials experienced by the NE electrolyte under conditions of storage and cycling of the electrochemical cell is resistant to reduction reactions. This reduction at the negative electrode will increase the electrical impedance of the cell, thus adversely affecting the performance of the cell and/or the capacity of the cell. In addition, the NE electrolyte is chemically stable with respect to the anode active material.

In one embodiment of the invention, the negative electrode assembly has a thin film or foil as the negative active material (as shown in fig. 1e), and the NE dry polymer electrolyte has a high modulus to prevent dendrite growth from the film during battery cycling. NE dry polymer electrolytes also have good adhesion to films or foils to ensure easy charge transfer and low interfacial resistance between layers. In one arrangement, the NE dry polymer electrolyte is void free. NE dry polymer electrolytes are electrochemically stable below the lowest operating potential of the electrode. For example, for a Li-Al planar electrode, NE Dry Polymer electrolyte is a relative of Li/Li⁺Is stable at 0.3V or less. See table 1 for other NE active materials and their associated potentials. In one arrangement, the mechanical rigidity of the NE dry polymer electrolyte is sufficient to prevent continued reactivity of the active material particles that undergo large volume changes during battery cycling by maintaining their electrical contact with the matrix of the composite electrode. When a negative electrode active material that undergoes large volume expansion upon lithium absorption is used as a thin film electrode, if the NE dry polymer electrolyte hasHigh yield strain can then be used to prevent electrode fatigue.

In another embodiment of the present invention, the anode active material is an alloy (examples of which are shown in table 1), and has a particle form. To prevent continued reactivity, it is useful if the NE electrolyte is electrochemically stable below the indicated reduction potential. In addition, it is useful if the NE electrolytes have high impact toughness in order to maintain mechanical strength and high yield strain in order to accommodate the volume change of the NE active material particles as they absorb or release lithium. It is also useful if the NE electrolyte contains voids that can shrink to accommodate expansion. Good compatibility between the electrolyte and the particle surface helps to ensure good adhesion and uniform dispersion. Finally, if a current collector is used, it is useful if the NE electrolyte can adhere to the current collector.

TABLE 1

Characteristics of negative active material

The negative active material may be any of various materials depending on the chemical type of the battery designed. In one embodiment of the invention, the battery is a lithium battery or a lithium ion battery. The anode material may be any material that can serve as a lithium ion host material (i.e., can absorb and release). Examples of such materials include, but are not limited to, graphite, lithium metal, and lithium alloys, such as Li-Al, Li-Si, Li-Sn, and Li-Mg. In one embodiment of the invention, a lithium alloy is used that contains no more than about 0.5 wt.% aluminum. Silicon and silicon alloys are known to be useful as negative electrode materials in lithium batteries. Examples include silicon alloys of tin (Sn), nickel (Ni), copper (Cu), iron (Fe), cobalt (Co), manganese (Mn), zinc (Zn), indium (In), silver (Ag), titanium (Ti), germanium (Ge), bismuth (Bi), antimony (Sb), and chromium (Cr), and mixtures thereof. In some embodiments, graphite, metal oxides, silicon oxide, or silicon carbide may also be used as the negative electrode material.

In one embodiment of the present invention, the positive electrode assembly comprises at least a positive electrode active material and an electrolyte (referred to herein as PE (positive electrode) electrolyte) that has been selected for use specifically with the positive electrode active material. Fig. 2 illustrates various exemplary arrangements of positive electrode active material (light gray area) and PE electrolyte (dark gray area). The positive active material may be provided as particles (fig. 2a-2d) or as a film or foil (fig. 2 e). The positive electrode assembly may be formed by combining positive electrode material particles with a PE electrolyte to form a composite layer (fig. 2a-2 d). In some arrangements, other materials (not shown) may be added to the composite layer to enhance, for example, electronic conduction. In some arrangements, the composite is porous, i.e. contains voids, which are shown as white voids in fig. 2b, 2 d; in other arrangements, the composite has no pores (fig. 2a, 2 c). In still other arrangements (not shown), the PE electrolytes shown in fig. 2e and 2f may also contain pores. In a positive electrode assembly having a composite layer, the PE electrolyte may be entirely contained in the composite layer (fig. 2a, 2 b). In another arrangement, there may be a thin layer of additional PE electrolyte adjacent to the composite layer (fig. 2c, 2 d). In some arrangements, the current collector (shown as a white layer defined by dashed lines) is also part of the positive electrode assembly.

In an arrangement where the positive electrode active material is a film or foil, as shown in fig. 2e, the positive electrode assembly comprises at least a film or foil and a PE electrolyte layer adjacent to and in ionic contact with the film or foil. In some arrangements, the positive electrode material is not a solid thin film, but is arranged as an aggregate of positive electrode active material particles, the particles being in close proximity to each other to ensure ionic and electronic communication between the particles (fig. 2 f). Such a structure may be prepared, for example, by pressing and/or sintering the positive electrode active material. In some arrangements, other materials, such as carbon particles, may be added to the positive electrode material particle layer, for example, to enhance electronic or ionic conductivity. The positive electrode assembly includes at least a PE electrolyte in ionic communication with the layer of positive electrode active material particles. In some arrangements, there is also a current collector (shown as a white layer defined by dashed lines) in electronic contact with the positive electrode.

The PE electrolyte is specifically selected for use with the positive electrode active material. In one embodiment of the invention, the PE electrolyte is a dry polymer (polymer with long chains that is not plasticized by small molecules) electrolyte. The PE electrolyte is selected to be oxidatively stable with respect to the positive electrode active material. That is, the PE electrolyte is resistant to successive chemical and electrochemical reactions that result in oxidation of the PE electrolyte at its interface with the cathode material. The PE electrolyte is resistant to oxidation reactions over the range of potentials experienced by the electrochemical cell under storage and cycling conditions. Such oxidation reactions at the positive electrode can increase the electrical impedance of the cell, thereby having a detrimental effect on the performance and/or capacity of the cell. In addition, the PE electrolyte is chemically stable with respect to the positive electrode active material.

The positive active material may be any of various materials depending on the chemical type of the battery design. In one embodiment of the invention, the battery is a lithium or lithium ion battery. The positive electrode active material may be any material that can serve as a matrix material for lithium ions. Examples of such materials include, but are not limited to, Li of the formula_xA_1-yM_yO₂The material described, wherein a comprises at least one transition metal selected from Mn, Co and Ni; m comprises at least one element selected from B, Mg, Ca, Sr, Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Al, In, Nb, Mo, W, Y and Rh; x is more than or equal to 0.05 and less than or equal to 1.1; and y is 0-0.5. In one embodiment, the positive electrode material is LiNi_0.5Mn_0.5O₂。

In one arrangement, the positive active material is described as being of the general formula Li_xMn_2-yM_yO₂Wherein M is selected from Mn, Ni, Co and/or Cr; x is more than or equal to 0.05 and less than or equal to 1.1; and y is 0-2. In another arrangement, the positive electrode active material is described as being of the general formula Li_xM_yMn_4-yO₈Wherein M is selected from Fe and/or Co; x is more than or equal to 0.05 and less than or equal to 2; and y is 0-4. In another arrangement, the positive electrode active material has the general formula Li_x(Fe_yM_1-y)PO₄Wherein M is selected from transition metals such as Mn, Co and/or Ni; x is more than or equal to 0.9 and less than or equal to 1.1; and y is 0-1. In still another arrangement, the positive electrode active material has a general formula of Li (Ni)_0.5-xCo_0.5-xM_2x)O₂Wherein M is selected from Al, Mg, Mn and/or Ti; and x is 0-0.2. In some arrangements, the positive electrode material comprises LiNiVO₂。

Most electrolytes have electrochemical stability during a limited window of about 4 volts. A single electrolyte cannot by itself maintain an electrochemical pair with a voltage between the electrodes higher than 4 volts. Such high voltage electrochemical cells can be made stable and robust using the structures and materials described herein. Two different electrolytes are currently available in the same electrochemical cell-NE dry polymer electrolyte that is stable for reduction at the anode (but can be oxidatively stable or can be oxidatively unstable at the cathode) and PE dry polymer electrolyte that is stable for oxidation at the cathode (but can be stable for reduction or can be reductively unstable at the anode). In one embodiment of the present invention, the NE dry polymer electrolyte is optimized to be reductively stable and the NE dry polymer electrolyte is optimized to be oxidatively stable. By allowing different electrolytes to be used for the negative and positive electrodes, each electrode can be designed for optimal performance without compromise. This arrangement is particularly useful for high voltage applications.

Efforts have been made in recent years to develop high voltage (i.e., greater than-4.2V) electrochemical cells by utilizing the "high voltage cathode materials" listed in table 2. Unfortunately, electrolytes that are oxidatively stable at high potentials at the cathode/electrolyte interface are generally not stable to reduction at low potentials at the anode/electrolyte interface of standard anode materials. As described herein, electrochemical cells that currently use different, specifically selected electrolytes (e.g., dry polymer electrolytes) on the cathode and anode sides of the cell can overcome this problem and enable the design and manufacture of high voltage cells.

TABLE 2

Positive electrode active material characteristics

Lithium metal and alloy negative electrode active materials are particularly prone to reduction reactions with many conventional lithium ion electrolytes because these negative electrode active materials do not tend to form stable passivation layers. While some electrolytes may form a stable interface with such anode materials, these electrolytes do not work effectively in the rest of the battery or in the positive electrode assembly due to limitations in conductivity and/or oxidative stability. These limitations may be overcome using electrochemical cells that specifically select different electrolytes compatible with each electrode, as described in embodiments herein.

The above-described embodiments of the present invention may result in electrochemical cells having very good performance. In one embodiment of the invention, the Li-cycle efficiency of such a cell is greater than 99.7% during 500 cycles. In another embodiment of the invention, the Li-cycle efficiency of such a cell is greater than 99.9% during 500 cycles. In another embodiment of the invention, there is little increase in impedance at the negative electrode, the positive electrode, or both electrodes when the battery is cycled. In one arrangement, the increase in impedance value from 10 cycles to 500 cycles does not exceed 40%. In another arrangement, the increase in impedance value from 10 cycles to 500 cycles does not exceed 20%. In yet another arrangement, the increase in impedance value from 10 cycles to 500 cycles does not exceed 10%. In one embodiment of the invention, the electrochemical cell does not decrease by more than 40% from a capacity of 10 cycles to a capacity of 500 cycles. In another embodiment of the invention, the electrochemical cell does not decrease by more than 20% from a capacity of 10 cycles to a capacity of 500 cycles. In yet another embodiment of the present invention, the electrochemical cell does not decrease by more than 10% from a capacity of 10 cycles to a capacity of 500 cycles. In yet another embodiment of the present invention, the electrochemical cell does not decrease by more than 5% from a capacity of 10 cycles to a capacity of 500 cycles.

When the negative and positive electrode assemblies are each independently optimized, not only can electrochemical stability be optimized, but there is also an opportunity to overcome other important limitations that may be specific to the individual electrode active materials.

For example, some negative active materials undergo a large volume increase, such as 300% or more, upon lithiation. Some examples are shown in table 1 above. For composite negative electrode assemblies containing voids, such as the electrode assemblies in fig. 1b, 1d, volume expansion and contraction of the negative active material upon cycling can be accommodated. It is useful if the NE electrolyte is a dry polymer electrolyte having a yield strain greater than or equal to the maximum volume expansion of the anode material. In this way, the NE electrolyte is sufficiently elastic to move into the void space when the anode active material expands. It is also useful if the total void space is as large as the maximum total volume expansion of the negative active material. In other arrangements, the anode material active is formed as a porous layer adjacent to the NE electrolyte layer to form an anode assembly as shown in fig. 1 f. These pores in the layer may accommodate expansion of the negative active material. Further details regarding porous electrodes may be found in international application PCT/US09/52511, filed on 31/7/2009, which is incorporated herein by reference.

Generally, the cathode active material expands and contracts much less than the anode active material during battery cycling. Thus, when selecting an electrolyte for the cathode rather than the anode, different mechanical considerations are made and it is desirable to select an electrolyte for the two regions of the electrochemical cell that is different. For example, if the positive active material expands and contracts much less than the negative active material, it is optimal to use a less elastic electrolyte for the cathode of the battery or an electrode assembly that produces a cathode without voids, thereby optimizing other important parameters in the cathode assembly such as mechanical toughness or energy density. One of the key factors in determining a good PE dry polymer electrolyte is whether the electrolyte can bind and keep the positive active material particles and any electron conducting additives (e.g., carbon particles) mixed and randomly dispersed through the manufacturing process (e.g., casting, calendering) despite the significant difference in particle density.

For positive active materials comprising transition metals, dissolution of these metals into standard liquid electrolytes on cycling can be a serious problem, particularly in high voltage batteries and at high temperatures. Dissolution can cause accelerated battery degradation or premature failure. Examples of possible failure mechanisms include:

a) as the metal dissolves, the composition of the positive electrode active material changes, adversely affecting the ability of the active material to absorb and release lithium,

b) the dissolved metal may diffuse to the anode and degrade the capacity of the anode active material,

c) the dissolved metal may diffuse to the negative electrode and degrade a passivation layer on the negative electrode active material layer, resulting in a continuous electrolyte reaction with the negative electrode active material, and

d) the dissolved metal can create internal shorts or other defects in the battery.

For example, in Mn₂O₄In the case of a positive electrode active material, it is useful if the electrolyte does not dissolve the electrochemically active manganese. In the case of sulfur cathodes, it is useful if the electrolyte does not dissolve the electrochemically active polysulfides. In one arrangement, less than 10% of the electrochemically active ions are dissolved from the positive electrode active material after 500 cycles at 45-80 ℃. In another arrangement, less than 5% of the electrochemically active ions are dissolved from the positive electrode active material after 500 cycles at 45-80 ℃. In yet another embodiment, less than 1% of the electrochemically active ions are dissolved from the positive electrode active material after 500 cycles at 45-80 ℃. This allows the selection of an electrolyte that is insoluble on the cathode side alone and can prevent diffusion of metal to the anode. The positive electrode assembly can be optimized to resist dissolution (e.g., by employing a ceramic or solid polymer electrolyte). While elution of electrochemically active ions may not be a problem for the negative electrode assembly, other considerations (such as high ionic conductivity or reduction stability) may be important, and different electrolytes may be preferred.

In one embodiment of the invention, the NE electrolyte and/or the PE electrolyte is a solid electrolyte. In one arrangement, the NE electrolyte and/or the PE electrolyte is a ceramic electrolyte. In another embodiment, the NE electrolyte and/or the PE electrolyte is a dry polymer electrolyte. In yet another embodiment, the NE electrolyte and/or the PE electrolyte is a dry block copolymer electrolyte.

In one embodiment of the invention, the NE electrolyte and/or the PE electrolyte is a liquid electrolyte or a gel containing a liquid electrolyte. When a liquid electrolyte is used, it is most useful if the liquid electrolyte is immiscible with the electrolyte in the adjacent region of the cell or a selectively permeable membrane is positioned to prevent mixing of the liquid electrolyte with the adjacent electrolyte. Such membranes allow electrochemical cations to move through, but do not allow the liquid itself to pass through. In the absence of such a membrane to prevent leakage, miscible liquids can readily diffuse throughout the cell. If such diffusion occurs, the advantages of using different electrolytes in different regions of the cell will be reduced or eliminated. In the worst case, the active material in the electrode may be oxidized or reduced, seriously affecting the performance and/or life of the battery.

In one embodiment of the invention, a separator electrolyte is used between the negative electrode assembly and the positive electrode assembly. In one embodiment of the present invention, the separator electrolyte may be the same as the NE electrolyte or the PE electrolyte. In another embodiment, the separator electrolyte is different from the NE electrolyte and the PE electrolyte. The separator electrolyte may be any one of a liquid electrolyte, a solid electrolyte, a polymer electrolyte, a dry polymer electrolyte and a block copolymer electrolyte, and the NE electrolyte and the PE electrolyte are independent of each other. In some arrangements, the electrolytes are selected so that no two electrolytes are adjacent to each other. When a liquid electrolyte is used, it is most useful if the liquid electrolyte does not mix with the electrolyte of adjacent regions of the cell or if a selective membrane is placed at each interface to prevent mixing of the liquid electrolyte with the adjacent electrolyte. Such membranes allow electrochemical cations to move through, but do not allow the liquid itself to pass through. In the absence of leakage prevention, miscible liquids can readily diffuse throughout the cell. If such diffusion occurs, the advantages of using different electrolytes in different regions of the cell may be reduced or eliminated. In the worst case, this diffusion can lead to reduction on the negative electrode assembly and/or oxidation on the positive electrode assembly, leading to premature failure of the battery.

Generally, it is useful if the separator electrolyte has sufficient mechanical integrity to ensure that the negative and positive electrode assemblies are not in electrical contact with each other. In some embodiments, when a liquid, gel, or soft polymer is used as the separator electrolyte, a membrane of the separator is used therewith.

It is useful if any two electrolytes in contact at the interface are immiscible with each other and chemically compatible with each other. It is also useful if there is little or no electrical impedance or concentration overpotential across the interface.

In one arrangement, all of the electrolyte is stable over the storage and operating temperature range as well as the operating potential range of the electrochemical cell. With the embodiments described herein, such conditions may satisfy the requirements of the electrode pair, which is instead unstable with conventional electrolytes or in conventional single-electrolyte structures.

Fig. 3 is a cross-sectional view of an electrochemical cell showing an exemplary embodiment of the present invention. Battery 300 has a negative electrode assembly 310, a positive electrode assembly 320, and an intervening separator 330. The exemplary negative electrode assembly 310 is the same as that shown in fig. 1 a. The negative electrode assembly 310 is an aggregate of negative electrode active material particles 314 dispersed in NE dry polymer electrolyte 318. There may also be conductive particles, such as carbon particles (not shown), in the negative electrode assembly 310. The exemplary positive electrode assembly 320 is the same as that shown in fig. 2 a. The positive electrode assembly 320 is an aggregate of positive electrode active material particles 324 dispersed in a PE dry polymer electrolyte 328. There may also be electrically conductive particles such as carbon particles (not shown) in positive electrode assembly 320. In other exemplary embodiments, other electrode assembly configurations, such as those shown in fig. 1 and 2, may be substituted in the electrochemical cell shown in fig. 3.

NE electrolyte 318 and PE electrolyte 328 are each optimized for the respective electrodes discussed above. In one arrangement, the NE electrolyte 318 and the PE electrolyte 328 are different. In another arrangement, the NE electrolyte 318 and the PE electrolyte 328 are the same. Separator 330 includes a separator electrolyte 338, which is also optimized for its function in battery 300. In one arrangement, the separator electrolyte 338 is immiscible with the NE electrolyte 318 and the PE electrolyte 328. In another arrangement, the membrane electrolyte 338 is miscible with one or both of the NE electrolyte 318 and the PE electrolyte 328, and a selectively permeable membrane (not shown) is disposed at the interface between the miscible electrolytes. In one arrangement, the separator electrolyte 338 is the same as the NE electrolyte 318 or the PE electrolyte 328. In another arrangement, the separator electrolyte 338 is different from both the NE electrolyte 318 and the PE electrolyte 328.

In one arrangement, NE electrolyte 318, PE electrolyte 328, and diaphragm electrolyte 338 are all solid electrolytes. In some arrangements, the solid electrolyte may be made of a ceramic material or a polymeric material. In one arrangement, the solid electrolyte may be made of a dry polymer material. In one arrangement, the solid electrolyte is a block copolymer electrolyte. In some arrangements, one or more of NE electrolyte 318, PE electrolyte 328, and membrane electrolyte 338 are liquid. When using liquid electrolytes, care must be taken to ensure that the liquid cannot diffuse out of its functional area (i.e., the negative electrode assembly, the positive electrode assembly, or the separator) into other functional areas of the cell. In some arrangements, a permselective membrane is used at any interface where at least one electrolyte is a liquid. In other arrangements, the liquid electrolyte used is immiscible with any adjacent electrolyte.

Electrolyte

Examples of ceramic electrolytes useful in embodiments of the present invention include lithium silicate, lithium borate, lithium aluminate, lithium phosphate, lithium phosphorus oxynitride, lithium silicon sulfide (lithium silicosulfide), lithium boron sulfide (lithium borosulide), lithium aluminum sulfide (lithium aluminosulide), and lithium phosphorous sulfide (lithium phosphosulide).

There are a variety of polymer electrolytes suitable for use in the inventive structures described herein. In one embodiment of the invention, the electrolyte comprises one or more of the following optional cross-linkersThe polymer of the block: polyethylene oxide, polysulfone, polyacrylonitrile, silicone, polyether, polyurethane, linear copolymer containing ether or amine, ethylene carbonate, NafionAnd polysiloxanes grafted with oligomers or small molecules including polyethers and/or alkyl carbonates.

In one embodiment of the invention, the solid polymer electrolyte, when combined with a suitable salt, is chemically and thermally stable and has a temperature of at least 10 deg.f at the desired operating temperature^-5Scm^-1Ion conductivity of (2). Examples of suitable salts include, but are not limited to, metal salts selected from the group consisting of: chlorides, bromides, sulfates, nitrates, sulfides, hydrides, nitrides, phosphides, sulfonamides, triflates (triflates), thiocyanates, perchlorates, borates, or selenides of lithium, sodium, potassium, silver, barium, lead, calcium, ruthenium, tantalum, rhodium, iridium, cobalt, nickel, molybdenum, tungsten, or vanadium. Examples of specific lithium salts include LiSCN, LiN (CN)₂、LiClO₄、LiBF₄、LiAsF₆、LiPF₆、LiCF₃SO₃、Li(CF₃SO₂)₂N、Li(CF₃SO₂)₃C、LiN(SO₂C₂F₅)₂、LiN(SO₂CF₃)₂、LiN(SO₂CF₂CF₃)₂Lithium alkyl fluorophosphates, lithium oxalato borate (lithium oxalato borate) and other lithium bis (chelated) borates with 5-7 membered rings, lithium bis (trifluoromethanesulfonimide) (LiTFSI), LiPF₃(C₂F₅)₃、LiPF₃(CF₃)₃、LiB(C₂O₄)₂And mixtures thereof. In other embodiments of the invention, for other electrochemistry, electrolytes can be prepared by combining the polymer with various types of salts. Examples include, but are not limited to, AgSO₃CF₃、NaSCN、NaSO₃CF₃、KTFSI、NaTFSI、Ba(TFSI)₂、Pb(TFSI)₂And Ca (TFSI)₂. As detailed above, block copolymer electrolytes may be used in embodiments of the present invention.

Fig. 4A is a simplified illustration of an exemplary diblock polymer molecule 400 having a first polymer block 410 and a second polymer block 420 covalently bonded together. In one arrangement, the first polymer block 410 and the second polymer block 420 are both linear polymer blocks. In another arrangement, one or both polymer blocks 410, 420 have a comb-type structure. In one arrangement, none of the polymer blocks are crosslinked. In another arrangement, one polymer block is crosslinked. In yet another arrangement, the two polymer blocks are crosslinked.

As shown in fig. 4B, the plurality of diblock polymer molecules 400 may arrange themselves to form first regions 415 of a first phase made of the first polymer block 410 and second regions 425 of a second phase made of the second polymer block 420. As shown in fig. 4C, the diblock polymer molecule 400 may arrange itself to form a plurality of repeating regions, thereby forming a continuous nanostructured block copolymer material 440. The size or width of the domains can be adjusted by adjusting the molecular weight of each polymer block.

In one arrangement, the first polymer regions 415 are ionically conductive and the second polymer regions 425 provide mechanical strength to the nanostructured block copolymer.

Fig. 5A is a simplified illustration of an exemplary triblock copolymer molecule 500 having a first polymer block 510a, a second polymer block 520, and a third polymer block 510b that is identical to the first polymer block 510a covalently bonded together. In one arrangement, the first polymer block 510a, the second polymer block 520, and the third polymer block 510b are linear polymer blocks. In another arrangement, some or all of the polymer blocks 510a, 520, 510b have a comb-type structure. In one arrangement, no polymer blocks are crosslinked. In another arrangement, one polymer block is crosslinked. In yet another arrangement, the two polymer blocks are crosslinked. In yet another arrangement, all of the polymer blocks are crosslinked.

As shown in fig. 5B, the plurality of triblock polymer molecules 500 may arrange themselves to form a first region 515 of a first phase made of a first polymer block 510a, a second region 525 of a second phase made of a second polymer block 520, and a third region 515B of the first phase made of a third polymer block 510B. As shown in fig. 5C, triblock polymer molecule 500 may arrange itself to form multiple repeating regions 425, 415 (including 415a and 415b), thereby forming continuous nanostructured block copolymer 530. The size of these regions can be adjusted by adjusting the molecular weight of each polymer block.

In one arrangement, the first and third polymer regions 515a, 515b are ionically conductive and the second polymer region 525 provides mechanical strength to the nanostructured block polymer. In another arrangement, the second polymer region 525 is ionically conductive and the first and third polymer regions 515 provide a structural framework.

Fig. 6A briefly illustrates another exemplary triblock polymer molecule 600 having a first polymer block 610, a second polymer block 620, and a third polymer block 630 that is different from the other two polymer blocks, all of which are bonded together by covalent bonds. In one arrangement, the first polymer block 610, the second polymer block 620, and the third polymer block 630 are linear polymer blocks. In another arrangement, some or all of the polymer blocks 610, 620, 630 have a comb-type structure. In one arrangement, no polymer blocks are crosslinked. In another arrangement, one polymer block is crosslinked. In yet another arrangement, the two polymer blocks are crosslinked. In yet another arrangement, all of the polymer blocks are crosslinked.

As shown in fig. 6B, the plurality of triblock polymer molecules 600 may arrange themselves to form a first region 615 of a first phase made of first polymer block 610a, a second region 625 of a second phase made of second polymer block 620, and a third region 635 of a third phase made of third polymer block 630. As shown in fig. 6C, triblock polymer molecules 600 may arrange themselves to form multiple repeating regions, thereby forming a continuous nanostructured block copolymer 640. The size of these regions is adjusted by adjusting the molecular weight of each polymer block.

In one arrangement, 615 of the first polymer regions are ion conducting and the second polymer regions 625 provide mechanical strength to the nanostructured block copolymer. The third polymer region 635 provides additional functions that can improve mechanical strength, ionic conductivity, chemical or electrochemical stability, can make the material easier to process, or can provide some other desired property to the block copolymer. In other arrangements, separate regions may be used interchangeably.

In order to achieve the desired electrolyte properties, it is important to select a polymer suitable for use in the above-described block copolymer. In one embodiment, the conductive polymer (1), when combined with a suitable salt such as a lithium salt, has a conductivity of at least 10 at the operating temperature of the electrochemical cell^-5Scm^-1(ii) a (2) Chemically stable with respect to such salt species; and (3) is thermally stable at the electrochemical cell operating temperature. In one embodiment, the structural material has a temperature in excess of 1 x 10 at the operating temperature of the electrochemical cell⁵Pa modulus. In one embodiment, the third polymer (1) is elastic; and (2) having a glass transition temperature below the operating and processing temperatures. It is useful if all materials are immiscible with each other.

In one embodiment of the invention, the conductive phase may be made of a linear polymer. Conductive linear polymers that may be used in the conductive phase include, but are not limited to, polyethers, polyurethanes, polyimides, polyamides, alkyl carbonates, polynitriles, and combinations thereof. The electrically conductive linear polymers may also be used in combination with silicones, polyphosphazines, polyolefins and/or polydienes to form the electrically conductive phase.

In another exemplary embodiment, the conductive phase is made of a comb polymer having a backbone and pendant groups. Backbones that can be used for these polymers include, but are not limited to, polysiloxanes, polyphosphazines, polyethylenes, polydienes, polyolefins, polyacrylates, polymethacrylates, and mixtures thereof. Useful side groups include, but are not limited to, oligoethers, substituted oligoethers, nitriles, sulfones, thiols, polyethers, polyamines, polyimides, polyamides, alkyl carbonates, polynitriles, other polar groups, and combinations thereof.

More details regarding the phases that may be used in the conductive phase may be found in international application PCT/US09/45356 filed on 5/27 th 2009, international application PCT/US09/54709 filed on 8/22 th 2009, U.S. provisional application 61/145518 filed on 1/16 th 2009, U.S. provisional application 61/145507 filed on 1/16 th 2009, U.S. provisional application 61/158257 filed on 3/6 th 2009, and U.S. provisional application 61/158241 filed on 3/6 th 2009, the entire contents of which are incorporated herein by reference.

There is no particular limitation on the electrolyte salt that can be used for the block polymer electrolyte. Any electrolyte salt that includes an ion that is the most desirable charge carrier for the present application may be used. Particularly, it is useful for an electrolyte salt having a large dissociation constant in a polymer electrolyte.

Suitable examples include alkali metal salts, such as lithium salts. Examples of useful lithium salts include, but are not limited to, LiPF₆、LiN(CF₃SO₂)₂、Li(CF₃SO₂)₃C、LiN(SO₂CF₂CF₃)₂、LiB(C₂O₄)₂、B₁₂F_xH_12-x、B₁₂F₁₂And mixtures thereof. Non-lithium salts such as aluminum, sodium, and magnesium salts are examples of other useful salts.

In one embodiment of the invention, a single ion conductor may be used with or in place of an electrolyte salt. Examples of single ion conductors include, but are not limited to, sulfonamide salts, boron-based salts, and sulfate salts.

In one embodiment of the invention, the structural phase may be formed from polymers such as polystyrene, hydrogenated polystyrene, polymethacrylate, poly (methyl methacrylate), polyvinylpyridine, polyvinylcyclohexane, polyimide, polyamide, polypropylene, polyolefins, poly (t-butyl vinyl ether), poly (cyclohexyl methacrylate), poly (cyclohexyl vinyl ether), poly (t-butyl vinyl ether), polyethylene, fluorocarbons such as polyvinylidene fluoride, or copolymers containing styrene, methacrylate or vinylpyridine.

Additional species may be added to the nanostructured block copolymer electrolyte to increase ionic conductivity, to increase mechanical properties, or to increase any other desired property.

The ionic conductivity of the nanostructured block copolymer electrolyte material can be improved by including one or more additives in the ionically conductive phase. The additive may increase ionic conductivity by decreasing crystallinity, decreasing melting temperature, decreasing glass transition temperature, increasing chain mobility, or any combination thereof. The high dielectric constant additive can help dissociate salts, increasing Li available for ion transport⁺In quantity and reduced in bulk Li⁺[ salt]A complex compound. Weakening of Li⁺And PEO chains/anions to Li⁺An additive that readily diffuses ions may be included in the conductive phase. Additives that improve ionic conductivity can be broadly classified into the following categories: low molecular weight conductive polymers, ceramic particles, Room Temperature Ionic Liquids (RTILs), high dielectric constant organic plasticizers, and lewis acids.

Other additives may be used in the polymers described herein. For example, additives that contribute to overload protection, provide a stable SEI (solid electrolyte interface) layer, and/or improve electrochemical stability may be used. These additives are well known to those skilled in the art. Additives which make the polymer easy to process, such as plasticizers, may also be used.

In one embodiment of the invention, neither small molecules nor plasticizers are added to the block copolymer electrolyte, and the block copolymer electrolyte is a dry polymer.

More details regarding block copolymer electrolytes are described in U.S. patent application 12/225934 filed on 10.1.2008, U.S. patent application 12/2711828 filed on 11.14.2008, and international patent application PCT/US09/31356 filed on 1.16.2009, the entire contents of which are incorporated herein by reference.

Examples

The ionic conductivity of each component of the battery can be determined. In general, the conductivity G is expressed as:

where σ is the ionic conductivity, A is the cross-sectional area, and l is the length. Two conductivities G in series₁、G₂Total conductivity G_totComprises the following steps:

when the electrode assembly has a composite configuration, the ionic conductivity can be easily calculated from formula (1). When the electrode assembly has a multilayer configuration, the conductivity of each layer is found, and the total conductivity is given by formula (2). In one embodiment of the invention, the electrical conductivity of the negative electrode assembly and the electrical conductivity of the positive electrode assembly do not differ by more than 25%. In another embodiment of the present invention, the conductivity of the NE electrode assembly, the conductivity of the PE electrode assembly, and the conductivity of the separator electrolyte are within 25% of each other. Matching the conductivity in this manner may result in a cell having optimized minimum impedance characteristics.

Fig. 7 shows a complex impedance plot for a single electrolyte system (x) and a dual electrolyte system (o). The dual electrolyte battery has a first dry polymer electrolyte optimized for stability of the lithium metal anode film and a second dry polymer electrolyte optimized for low interfacial resistance of the composite cathode. The single electrolyte battery contains only the first dry polymer electrolyte. As is well known to those skilled in the art, the size of the dynamic curve (kinetic arc) in the graph reflects the total resistance of the system. It is contemplated that adding an additional interface (first polymer electrolyte/second polymer electrolyte interface) may add additional resistance to the system. However, surprisingly, the dual electrolyte system has a lower total resistance than the single electrolyte system, as indicated by the smaller dynamic curve (o). The use of multiple electrolytes that optimize their function in the cell has significant advantages.

Fig. 8A shows specific capacity data during 500 cycles for a battery comprising one dry polymer electrolyte, a lithium metal anode, and a lithium iron phosphate composite cathode. There was no measurable capacity fade during 100 cycles. After 500 cycles, the capacity fade was estimated to be about 5%. Fig. 8B shows specific capacity data for the dual electrolyte battery over 100 cycles. There is a first dry polymer electrolyte optimized for stability of the lithium metal anode film and a second dry polymer electrolyte optimized for conductivity in and on the composite cathode. Also, there was no measurable capacity fade during 100 cycles, indicating no adverse effects from using the multilayer electrolyte.

The present invention has been described herein in considerable detail in order to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components. However, it should be understood that: the invention may be carried out by different equipment, materials and devices, and various modifications, both as to the equipment and operating procedures, may be accomplished without departing from the scope of the invention itself.

Claims (49)

1. An electrochemical cell, comprising: a negative electrode assembly including a negative electrode active material and a negative electrode electrolyte, the negative electrode electrolyte being reductively stable with respect to the negative electrode active material; and

a positive electrode assembly including a positive electrode active material and a positive electrode electrolyte, the positive electrode electrolyte being oxidatively stable with respect to the positive electrode active material;

wherein the negative electrolyte and the positive electrolyte are different; and

wherein at least one of the negative electrolyte and the positive electrolyte comprises a nanostructured block copolymer comprising:

a plurality of ionically conductive first blocks arranged into first regions of a first ionically conductive phase;

a plurality of second blocks providing mechanical strength, the plurality of second blocks arranged into second regions of a second structural phase; and

a metal salt.

2. The electrochemical cell of claim 1, wherein at least one of the negative electrolyte and the positive electrolyte comprises a dry polymer.

3. The electrochemical cell of claim 1, wherein the negative and positive electrolytes comprise at least one lithium salt.

4. The electrochemical cell of claim 1, further comprising: electron conductive particles in at least a portion of the negative electrode assembly and at least a portion of the positive electrode assembly.

5. The electrochemical cell of claim 1, further comprising a separator electrolyte between the negative electrode assembly and the positive electrode assembly.

6. The electrochemical cell of claim 1, wherein the negative electrode assembly comprises particles of a negative electrode active material mixed with a negative electrode electrolyte.

7. The electrochemical cell of claim 1, wherein the negative active material comprises graphite.

8. The electrochemical cell as recited in claim 1, wherein the negative active material comprises lithium metal.

9. The electrochemical cell of claim 1, wherein the negative active material comprises a material selected from the group consisting of: Li-Al, Li-Si, Li-Sn and Li-Mg.

10. The electrochemical cell of claim 1, wherein the negative active material comprises a material selected from the group consisting of: silicon, silicon alloys of tin (Sn), nickel (Ni), copper (Cu), iron (Fe), cobalt (Co), manganese (Mn), zinc (Zn), indium (In), silver (Ag), titanium (Ti), germanium (Ge), bismuth (Bi), antimony (Sb), and chromium (Cr), silicon oxide, silicon carbide, graphite, and mixtures thereof.

11. The electrochemical cell of claim 1, wherein the negative electrode assembly comprises a layer comprising the negative electrode active material adjacent to the negative electrode electrolyte layer.

12. The electrochemical cell of claim 11, wherein the negative active material comprises lithium or lithium alloy foil.

13. The electrochemical cell of claim 12, wherein the lithium alloy foil comprises a lithium-aluminum alloy having an aluminum content of no greater than 0.5 wt.%.

14. The electrochemical cell of claim 1, wherein the negative electrode electrolyte is a solid electrolyte having a yield strain greater than or equal to the maximum volume expansion of the negative electrode material.

15. The electrochemical cell of claim 1 wherein the negative electrode assembly further comprises a plurality of voids.

16. The electrochemical cell of claim 1, wherein the positive electrode assembly comprises particles of a positive electrode active material mixed with a positive electrode electrolyte.

17. The electrochemical cell of claim 1, wherein the positive electrode assembly includes a layer containing a positive electrode active material adjacent to the positive electrode electrolyte layer.

18. The electrochemical cell of claim 1 wherein the positive active material is described by the general formula LiA_1-y-xM_yB_xO₂Wherein A comprises at least one transition metal selected from Mn, Co and Ni; m comprises at least one element selected from B, Mg, Ca, Sr, Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Al, In, Nb, Mo, W, Y and Rh; b comprises at least one element selected from Al, Fe, Mn and Mg; x is more than or equal to 0 and less than or equal to 1; and y is 0-1.

19. The electrochemical cell of claim 1, wherein the positive active material is described by the general formula Li (Ni)_0.5-xCo_0.5-xM_2x)O₂Wherein M is selected from Al, Mg, Mn and Ti, and x is more than or equal to 0 and less than or equal to 0.2.

20. The electrochemical cell of claim 1, wherein the positive active material is described by the general formula Li (Ni)_0.5-xMn_0.5-xM_2x)O₂Wherein M is selected from Al, Mg, Co, Ti and Fe, and x is 0-0.2.

21. The electrochemical cell of claim 1 wherein the positive active material is described by the general formula Li_x(Fe_yM_1-y)PO₄Wherein M comprises at least one element selected from Mn, Co and Ni; x is more than or equal to 0.9 and less than or equal to 1.1; and y is 0-1.

22. The electrochemical cell of claim 1, wherein the positive electrode active material comprises electrochemically active cations, and less than 10% of the electrochemically active cations are dissolved from the positive electrode active material after 500 cycles at a temperature of 45-80 ℃.

23. The electrochemical cell of claim 1, wherein the positive electrode active material comprises electrochemically active cations, and less than 5% of the electrochemically active cations are dissolved from the positive electrode active material after 500 cycles at a temperature of 45-80 ℃.

24. The electrochemical cell of claim 1, wherein the positive electrode active material comprises electrochemically active cations, and less than 1% of the electrochemically active cations are dissolved from the positive electrode active material after 500 cycles at a temperature of 45-80 ℃.

25. The electrochemical cell of claim 1, wherein the block copolymer is a diblock copolymer or a triblock copolymer.

26. The electrochemical cell of claim 25, wherein the first block of the block copolymer is ionically conductive and is selected from the group consisting of polyethers, polyamines, polyimides, polyamides, alkyl carbonates, polynitriles, polysiloxanes, polyphosphazines, polyolefins, polydienes, and combinations thereof.

27. The electrochemical cell of claim 25, wherein the first block of the block copolymer comprises an ionically conductive comb polymer comprising a backbone and pendant groups.

28. The electrochemical cell as recited in claim 27, wherein the backbone comprises one or more selected from the group consisting of: polysiloxanes, polyphosphazines, polyethers, polydienes, polyolefins, polyacrylates, polymethacrylates, and combinations thereof.

29. The electrochemical cell of claim 27, wherein the side group comprises one or more selected from the group consisting of: oligoethers, substituted oligoethers, nitriles, sulfones, thiols, polyethers, polyamines, polyimides, polyamides, alkyl carbonates, polynitriles, other polar groups, and combinations thereof.

30. The electrochemical cell of claim 26, wherein the second block of the block copolymer is selected from the group consisting of polystyrene, hydrogenated polystyrene, polymethacrylate, poly (methyl methacrylate), polyvinylpyridine, polyvinylcyclohexane, polyimide, polyamide, polypropylene, polyolefins, poly (t-butyl vinyl ether), poly (cyclohexyl methacrylate), poly (cyclohexyl vinyl ether), poly (t-butyl vinyl ether), polyethylene, fluorocarbons, polyvinylidene fluoride, and copolymers comprising styrene, methacrylate, and/or vinylpyridine.

31. The electrochemical cell of claim 1, wherein the Li cycling efficiency during 500 cycles of the cell is greater than 99.9%.

32. The electrochemical cell of claim 1, wherein the Li cycling efficiency during 500 cycles of the cell is greater than 99.7%.

33. The electrochemical cell of claim 1, wherein the impedance value is present after 10 cycles of the negative electrode assembly and/or the positive electrode assembly, and the value does not increase by more than 40% over 500 cycles.

34. The electrochemical cell of claim 1, wherein the resistance value is present after 10 cycles of the negative electrode assembly and/or the positive electrode assembly, and the resistance does not increase by more than 20% at 500 cycles.

35. The electrochemical cell of claim 1, wherein the impedance value is present after 10 cycles of the negative electrode assembly and/or the positive electrode assembly, and does not increase by more than 10% over 500 cycles.

36. The electrochemical cell of claim 1, wherein a capacity value exists after 10 cycles and the value does not decrease by more than 40% over 500 cycles.

37. The electrochemical cell of claim 1, wherein the capacity value exists after 10 cycles and does not decrease by more than 20% after 500 cycles.

38. The electrochemical cell of claim 1, wherein the capacity value exists after 10 cycles and does not decrease by more than 10% over 500 cycles.

39. The electrochemical cell of claim 1, wherein the ionic conductivity of the negative electrode assembly differs from the ionic conductivity of the positive electrode assembly by no more than 25%.

40. The electrochemical cell of claim 1, further comprising a separator electrolyte between the negative electrode assembly and the positive electrode assembly, the separator electrolyte being different from at least one of the negative electrode electrolyte and/or the positive electrode electrolyte.

41. The electrochemical cell of claim 40, wherein the separator electrolyte is selected from the group consisting of ceramic electrolytes, polymer electrolytes, and block copolymer electrolytes.

42. The electrochemical cell as recited in claim 40, wherein the separator electrolyte comprises a solid electrolyte.

43. The electrochemical cell as recited in claim 40, wherein the conductivity of the negative electrode assembly, the conductivity of the positive electrode assembly, and the conductivity of the separator electrolyte are within 25% of each other.

44. An electrochemical cell, comprising:

a composite anode including an anode active material and an anode electrolyte, the anode electrolyte being reductively stable with respect to the anode active material;

a composite positive electrode including a positive active material and a positive electrolyte, the positive electrolyte being oxidatively stable with respect to the positive active material; and

a separator electrolyte between the negative electrode and the positive electrode;

wherein the negative electrolyte and the positive electrolyte are different; and

wherein at least one of the negative electrolyte and the positive electrolyte comprises a nanostructured block copolymer comprising:

a plurality of ionically conductive first blocks arranged into first regions of a first ionically conductive phase;

a plurality of second blocks providing mechanical strength, the plurality of second blocks arranged into second regions of a second structural phase; and

a metal salt.

45. The electrochemical cell of claim 44, wherein at least one of the negative electrolyte, the positive electrolyte, and the separator electrolyte comprises a dry polymer.

46. The electrochemical cell of claim 44, wherein the separator electrolyte is different from both the negative and positive electrolytes.

47. The electrochemical cell as recited in claim 44, wherein the negative electrode is adapted to accommodate volume expansion and contraction of the negative active material during cycling.

48. An electrochemical cell, comprising:

an anode including a lithium metal film and an anode electrolyte film that is stable in reducing property with respect to the lithium metal; and

a positive electrode comprising a nickel cobalt aluminum oxide and a positive electrode electrolyte oxidatively stable with respect to the nickel cobalt aluminum oxide;

wherein the negative electrolyte and the positive electrolyte are different; and

wherein at least one of the negative electrolyte and the positive electrolyte comprises a nanostructured block copolymer comprising:

a plurality of ionically conductive first blocks arranged into first regions of a first ionically conductive phase;

a plurality of second blocks providing mechanical strength, the plurality of second blocks arranged into second regions of a second structural phase; and

a metal salt.

49. The electrochemical cell of claim 48, wherein at least one of the negative electrolyte and the positive electrolyte comprises a dry polymer.