WO2024167933A1 - Extrusion of high-energy density polymer electrodes using gel electrolytes and solid polymer electrolytes - Google Patents

Abstract

Methods and techniques for forming a high-energy density solid-state battery are described. The battery may have a solid-state cathode, a solid-state anode, and a separator. The methods may include mixing an active material powder with a conductive carbon powder, dissolving a polymer electrolyte with a salt to form a solution, mixing the solution with the mixed powders to form a homogeneous mixture, and extruding the mixture through a die and/or between rolls to produce a smooth thin film.

Description

EXTRUSION OF HIGH-ENERGY DENSITY POLYMER ELECTRODES USING GEL

ELECTROLYTES AND SOLID POLYMER ELECTROLYTES

BACKGROUND

Battery electrode manufacturing historically uses a solvent casting process; this process requires mixing active material, conductive carbon, binder, and solvent to produce a slurry, then casting this slurry on a metal foil, drying off the solvent (which leaves behind a porous, solid film on the foil), and finally filling the porous layer with a liquid electrolyte.

SUMMARY

FIG. 1 shows a conventional casting process in which a slurry is first cast and then dried. This drying process is energy-intensive and requires a large manufacturing footprint. Typical solvents used in a conventional slurry casting method (e.g., N-Methyl-2-pyrrolidone, or NMP) are toxic and flammable (the flammability also requires higher capital costs for manufacturing set-ups, e.g., explosion-proof facilities). Also, the "mud-cracking" phenomenon, resulting from volume change in the electrode during drying, has limited electrode thickness, resulting in lower energy density (i.e., thinner) electrodes. Finally, the electrolyte filling process is an additional manufacturing step, and relies on sufficient wetting of the electrolyte into the electrode pores (limiting electrolyte selection, typically, to low viscosity formulations).

Electrode processing with plasticized polymers can provide an opportunity to remove the need for the drying step, thus reducing manufacturing energy, cost, and footprint. There are no toxic/flammable solvents that need to be removed or recovered. In addition, by removing the drying process, the mud-cracking phenomenon is avoided, enabling the use of thicker electrodes for higher energy density. Finally, as described in further detail below, solid-state manufacturing, using the electrolyte as a plasticizing agent during processing and then utilizing the polymer electrolyte as both catholyte and anolyte during processing (and/or designs that uses the inorganic electrolyte and/or a composite of polymer and inorganic electrolyte) does not require an additional electrolyte filling step during cell manufacturing.

Certain processing methods have, and continue to be, developed in academia and industry to eliminate the need for extra toxic/flammable solvents. Approaches have included fully dry processing and semi-solid processing.

In fully dry processing, Teflon powder is mixed with active material and conductive carbon without the need for processing solvent. The shear forces present during processing from extrusion or calendaring, are leveraged to plastically deform the binder, resulting in a thin, dry film. However, this process still requires an electrolyte filling step at the end and can face challenges when producing thicker electrodes because the shear forces required for manufacturing diminish at the midplane of the film during calendaring and extrusion processes.

In another emerging method, referred to as semi-solid processing, the liquid electrolyte for the cell functions as a plasticizing and lubricating agent, creating a high viscosity paste when mixed with the active material and conductive carbon. Applying adequate shear force during processing induces flow in the paste, it maintains a relatively rigid consistency, resisting typical stack pressures. This method eliminates the need for a separate electrolyte filling step, but the absence of a binder phase poses challenges in ensuring adhesion between the electrode and the metal foil. Consequently, achieving high energy density through double-sided coatings, or producing bulk rolls of electrodes for manufacturing efficiency, becomes a limitation for this method due to the electrode's lack of cohesive and adhesive strength needed for web handling operations.

In some aspects, a solvent-less battery electrode processing method is described. The method includes mixing an active material powder with a conductive carbon powder and a polymer electrolyte dissolved with a salt to form a mixture and extruding the mixture through a die and/or between rolls to form a thin film.

In these and other implementations, the dissolved polymer electrolyte may be a solid polymer electrolyte. In other implementations, the dissolved polymer electrolyte may be a gel- polymer precursor. The polymer electrolyte may be a solid ceramic electrolyte in a polymer matrix. In these and other implementations, the method may also include curing the thin film to cross-link the gel-polymer precursor and produce an electrode film. If desired, the thin film may be extruded directly onto a metal foil current collector.

In other aspects, a solvent-less battery electrode processing method is described. The method includes mixing a liquid electrolyte with a low viscosity small molecule gel precursor to formulate a plasticizer, mixing the plasticizer with conductive carbon and active material to produce a paste, and extruding the paste through a die or between rolls or both to form a thin film on a metal foil.

In yet another aspect, a method of manufacturing a high-energy density solid-state battery, wherein the battery comprises a solid-state cathode, a solid-state anode, and a separator is described. The method includes mixing an active material powder with a conductive carbon powder, dissolving a polymer electrolyte with a salt to form a solution, mixing the solution with the mixed powders to form a homogeneous mixture, and extruding the mixture through a die and/or between rolls to produce a smooth thin film.

In some implementations, the solid-state electrolyte is a solid polymer electrolyte. In other implementations, the solid-state electrolyte is a gel-polymer precursor. In select implementations, the solid-state electrolyte is a solid ceramic electrolyte in a polymer matrix. If desired, the thin film may be extruded directly onto a metal foil current collector. In some implementations, a high molecular weight polymer electrolyte may be mixed with plasticizers to form the gel-polymer precursor. In these and other implementations, the method may also include curing the thin film to cross-link the gel polymer precursor and produce an electrode film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an illustration of a conventional casting process in which a slurry is first cast and then dried;

FIG. 2 shows an illustration of a process for manufacturing a gel-polymer electrolyte, in accordance with some embodiments of the present disclosure;

FIG. 3A illustrates a sample electrolyte-gel precursor blend;

FIG. 3B illustrates a cured gel-polymer electrolyte (GPE) formed from the electrolytegel precursor blend of FIG. 3A;

FIG. 4 illustrates a sample process for manufacturing a solid polymer electrolyte, in accordance with some embodiments of the present disclosure;

FIG. 5 illustrates another sample process for manufacturing a solid polymer electrolyte, in accordance with some embodiments of the present disclosure; FIG. 6 illustrates a sample structure of a solid polymer electrolyte, in accordance with some embodiments of the present disclosure;

FIG. 7 shows a plot of viscosity versus frequency measurements for various lithium salts;

FIG. 8 shows a calibration curve graph of a sample dry powder feeder;

FIG. 9 shows a graph of measured viscosities for various NCM compounds;

FIG. 10 shows a graph of measured viscosities for polymer electrolytes made with PEG salts of varying molecular weights;

FIG. 11 shows a graph of the rheological behavior of anodes with varying graphite contents; and

FIG. 12 shows a graph comparing viscosity of NCM and graphite.

DETAILED DESCRIPTION

The described processes are solid-state electrode manufacturing methods that utilize a polymer electrolyte, a gel-polymer electrolyte, an inorganic electrolyte, or a composite of these materials.

Gel-Polymer Electrolyte

The disclosed methods of manufacturing with gel-polymer electrolyte utilize the liquid electrolyte, mixed with a gel precursor (low viscosity small-molecule, i.e., monomer), as the plasticizer phase during processing. An extruder is used to mix the powder (active material and conductive carbon) with the plasticizer to produce a paste, and the paste is then extruded (with a die) or calendered between roles, or both, to a thin film form factor on a metal foil. Finally, the paste undergoes a curing step (in situ) to produce a gel-polymer electrolyte (GPE) phase between the powder particles. FIG. 2 shows an illustration of a process for manufacturing a gel-polymer electrolyte, in accordance with some embodiments of the present disclosure.

Another method for manufacturing a gel-polymer electrolyte involves utilizing the liquid electrolyte mixed with a high molecular weight polymer as the plasticizer phase, thereby eliminating the need for a curing step. The GPE serves as a binder to promote cohesion within the electrode, and adhesion to the metal foil, while allowing for ionic conduction of the liquid electrolyte. FIG. 3 A illustrates a sample electrolyte-gel precursor blend and FIG. 3B illustrates a cured gel-polymer electrolyte (GPE) formed from the electrolyte-gel precursor blend of FIG. 3 A.

The disclosed methods of manufacturing a gel-polymer electrolyte do not require solvent drying (see above), no toxic/flammable solvents required (see above), and higher energy density (thicker) electrodes can be produced. No filling step is required because the curing reaction is performed in situ, with the liquid electrolyte present, and the gel provides sufficient adhesion/mechanical integrity for roll processing and double-sided coating.

Example Embodiments - G el- Polymer Electrolytes

Process methods are disclosed to extrude anodes and cathodes comprised of active material, conductive carbon, a liquid electrolyte (solvent and salts), and a gel-polymer precursor or high Mw polymer. Additionally, methods for processing a separator layer, consisting of inorganic or organic fillers, a liquid electrolyte, and a gel-polymer precursor or a high Mw polymer will be disclosed. The processes use a twin-screw extruder to mix the components, and the resulting paste is subsequently pumped through a die to form the extrudate, and finally calendered between rollers to form a thin film on a metal foil. The paste is then cured to cross-link or polymerize the gel precursor producing a mechanically robust electrode film that adheres to the metal foil. When employing a high molecular weight polymer, there may be no need for a curing step to facilitate cross-linking or polymerization.

Various chemistries for the gel-polymer electrolyte have been explored. The liquid electrolyte comprises most of the blend (typically greater than 80% by weight), while the gel precursor is added minimally to provide sufficient mechanics for the electrode. The liquid electrolyte is blend of one, or several, organic solvents with one, or several, lithium- containing salts. The gel precursor is a monomer or polymer that is miscible in the liquid electrolyte and has functional groups that can be polymerized or cross-linked in the presence of the liquid electrolyte. In some cases, if the gel precursor has a high enough molecular weight, it doesn't require functional groups for cross-linking or polymerization.

Viable approaches that have been validated include free-radical polymerization of acrylates, Aza- Michael addition of acrylates and amines or hydroxyls, thiol-ene reactions between acrylates and thiols, condensation of aldehydes and hydroxyls, and condensation of glycidyl ethers and hydroxyls. Various initiation mechanisms for the curing reaction have been validated, including thermal initiation for the free-radical polymerization of acrylates, electron beam initiation for the free-radical polymerization of acrylates (to reduce the processing time), and acid/base catalyzed cross-linking for the Aza-Michael, thiol-ene, and condensation reactions.

Other methods may employ similar processing equipment and the use of liquid electrolyte as a plasticizer for example, the semi-solid approach and dry process may use extruders and calender rolls for processing. The semi-solid approach may also use the liquid electrolyte as a plasticizer (although no gel precursor is included). Finally, chemically cross- linked polymer binders have been explored for electrode processing, however this is typically done without the presence of the liquid electrolyte in the paste (as in situ curing in the liquid electrolyte is often challenging).

Solid Polymer Electrolyte

The disclosed methods of manufacturing a solid polymer electrolyte use the polymer electrolyte, dissolved in a salt, to form a polymer electrolyte complex during processing. Twin screw extruder, single screw extruder, high shear planetary/internal mixer, high shear planetary/internal mixer along with a single screw can be used for the preparation of electrode paste composed of active material, conductive carbon, and polymer electrolyte salt, and the paste is then extruded (with a die) or calendered between roles, or both, to a thin film form factor on a metal foil. Current collectors can be double side coated. Two processes are feasible and contemplated herein (see FIGS. 4 and 5). FIG. 4 illustrates a first sample process for manufacturing a solid polymer electrolyte and FIG. 5 illustrates a second sample process for manufacturing a solid polymer electrolyte.

In the disclosed methods, active materials are mixed with conductive carbons using the powder mixers, then are fed into the extruder or the planetary/internal mixers. Polymer electrolyte dissolved with a salt is fed into the extruder or the planetary/internal mixers at the same time. Those components undergo the mixing process forming a film shape through the T-die, and it is coated on the current collector. Double-sided coated electrode for both cathode and anode can then be made. The polymer electrolytes serve as binders to promote cohesion within the electrode, and adhesion to the metal foil, while allowing for ionic conduction. The final structure of the resulting solid polymer electrode is shown in FIG. 6. The disclosed methods of manufacturing a solid polymer electrolyte have numerous advantages as compared to methods of the prior art. For example, the disclosed methods do not require any solvent drying and no toxic/flammable solvents are required. Furthermore, the disclosed methods allow for higher energy density (thicker) electrodes. No fdling steps are required, and the polymer electrolyte provides sufficient adhesion/mechanical integrity for roll processing and double-sided coating.

Example Embodiments - Solid Polymer Electrolytes

Processes have been developed to extrude anodes and cathodes comprised of active material, conductive carbon, polymer electrolyte salts, as well as a separator layer consisting of inorganic or organic fillers, a liquid electrolyte (solvent and salts), and a polymer electrolyte.

The processes use a twin-screw extruder or intensive high shear planetary /internal mixer to mix the components, and the resulting paste is subsequently pumped through a die to form the extrudate, and coated on the metal foil with forms of a thin film.

Various chemistries for polymer electrolyte have been explored. The polymer electrolytes for an anode may be a polymer electrolyte with a desired Tg < -20°C, a weight loss less than 1% at I00°C, a desired electrochemical stability of< l pA/cm2 corrosion current at 0

V (vs Li/Li+), and lithium-ion conductivity of > 0.5 mS/cm. This polymer electrolyte may also contain additives such as nano-sized ceramic fillers, molecular rheology modifiers, molecular conductivity modifiers, molecular electrochemical stability modifiers, or other polymers.

The polymer electrolyte for a cathode may be a polymer electrolyte with a Tg < -20 °C, weight loss less than 1% at 100 °C, electrochemical stability of < 1 pA/cm2 corrosion current at 4.3

V (vs Li/Li+), and lithium-ion conductivity of > 0.5 mS/cm. This polymer electrolyte may also contain additives such as nano-sized ceramic fillers, molecular rheology modifiers, molecular conductivity modifiers, molecular electrochemical stability modifiers, or other polymers.

Tn some embodiments, charge transfer complex polymer (CTCP) and/or chargetransfer co- polymer electrolyte may be used in connection with the disclosed methods. These materials belong to a class of composite electrolyte containing polymeric electron donors and monomeric/oligomeric electron acceptors, and possibly with moderate amount of small molecule additives. These materials may show improved ionic conductivity due to the charge-transfer between donor and acceptor.

For the more efficient powder mixing of active material and conductive carbons, a more intensive high shear planetary/internal mixer may be used, which is feasible for the ordered mixing or dry particle coating technology. This equipment can be used for mixing this premix powder with polymer electrolyte salt.

In select embodiments, either a twin-screw process or an intensive high shear planetary/internal mixing process can be applied, depending on the mixing efficiency. A single screw extruder may also be used by attaching to the planetary/internal mixer.

Various types of plasticizers may also be used, depending on the rheology of the polymer electrolyte. Various kinds of separator may be used, depending on the desired electrochemical performance.

Experimental Examples

Example 1 : Catholyte Preparation

Preparation of Polymer Electrolyte Polyethylene Oxide (PEO) (P4338: Mw 3,350, Sigma) polymer powder and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, ThermoFisher) as the lithium salt was dry mixed in a Speedmixer.

<|)5 mm zirconia beads were used as grinding or milling media to aid in the dispersion of the polymer and salt in a solution or suspension. The function of the media may be, at least in part, to provide shear forces and energy to break down agglomerates or aggregates of the polymer and salt particles, leading to better dispersion throughout the medium. Zirconia beads are sometimes used in such applications due to their hardness, chemical inertness, and resistance to corrosion, but other materials such as glass, steel, ceramic, and polymer beads could alternatively or additionally be used.

Speedmixer was processed as 800 rpm for 1.5 min

1,500 rpm for 1.5 min 2,000 rpm for 1.5 2,400 rpm for 1.5 min 2,600 rpm for 1.5min.

Zirconia beads were removed, and transparent PEO Li salt complex was obtained.

Lithium salts of various LiTFSI ratios (24.5, 39.4, 56.5 wt %) were made and viscosities of those samples were measured and compared in Fig. 7 using a rheometer (Anton Paar MCR 92). Complex viscosity was measured at the frequency of 0.01 ~ 100 Hz to fully characterize the shear dependency of the polymer electrolyte solution for compound extruder mixing, which is significant for the process optimization, quality control, and product performance. Shear strain was 1%, and measuring temperature was 30 °C. The lithium salts were well dissolved in PEO polymer host at the lithium salt content of 39.4 wt%, and showed the lowest viscosity of the three formulations tested. Therefore, 39.4 wt% of LiTFSI was selected in this example as the lithium salt ratio and it was anticipated that the lithium salt would undergo effective dissociation within the PEO polymer, leading to improved processability. Preparation of Dry Powder Blend

Premix of 98.7 wt% of NCM622 (BASF) and 1. 3 wt% concentration of the conductive additive LITX200 was incorporated into the formulation. Alternative conductive additives could also be considered for similar applications. These might include materials like carbon black, graphene, carbon nanotubes, or conductive polymers such as polyaniline or poly(3,4- ethylenedioxythiophene) (PEDOT). Each of these additives offers unique electrical and mechanical properties, and their suitability depends on factors such as compatibility with the polymer matrix, desired conductivity levels, and processing requirements. V-blender was used to make dry powder blender and V-Blender is a common dry powder mixer used in industries such as pharmaceutical, food and cosmetics for producing uniformly blended powders through the combined use of high shear mixing while tumbling the bulk powders inside the V-Blender. Those powders were mixed for 2 hours at the 80% speed along with 4>2 mm zirconia beads, and were separated from the beads using a steel mesh sieve. To address issues related to agglomeration and sedimentation of the premix, adjustments were made to both the V-blender speed and the quantity of zirconia beads. By fine-tuning these parameters, efforts were made to optimize the dispersion process and achieve a more uniform distribution of the components within the mixture.

Preparation of electrode paste

Extruder mixing of the electrode paste was made using an <j) 11mm twin screw extruder (ThermoFisher Pharml 1) attached with a slot-die (30mm wide, 0.5mm thick) was used for casting the product into an electrode film composed of the PEO salts and the dry powder blend prepared separately. The premix powder feeder was calibrated prior to use by accurately measuring the powder feed rate dispensed across various machine settings. The calibration process involved establishing a calibration curve for the dry powder feeder, detailing the relationship between the machine settings and the corresponding powder feed rates. FIG. 8 illustrates the calibration curve of the dry powder feeder. From this result, the dry powder feeder was adjusted depending on the desired active material content and castability of the electrode film.

The polymer electrolyte was fed using a peristaltic pump to achieve the correct ratio powder to polymer electrolyte components. Flow rate of polymer electrolyte was 1.093 kg/hr. Twin screw elements configuration composed of feeding and mixing sections was used to obtain an optimum extruder mixing. The twin-screw extruder operated at a screw speed of 100 rpm, with consistent extruder temperatures maintained at 25°C across all sections. Through the manipulation of premix feeding rates while ensuring a consistent polymer electrolyte rate, electrode films with varying NMC contents ranging from 40% to 65% volume were processed. Smooth-surfaced electrode films were successfully produced up to 60% volume NMC content. However, achieving a smooth surface became challenging at 65% volume NMC content. Rheological behaviors associated with different NMC contents were illustrated in FIG. 9.

In FIG. 10, the viscosities of polymer electrolytes made from various molecular weights of PEG (Polyethylene Oxide) salts are compared. Specifically, PEO with a molecular weight of 10,000 displayed notably higher viscosity when compared to PEO with molecular weights of 3,350 and 8,000. This comparison offers insights into how the molecular weight of PEO influences the viscosity of the resulting polymer electrolyte.

Example 2: Anolyte Preparation

Preparation of polymer electrolyte The same materials and procedures as those used in example 1 were used for this experimental example.

Preparation of dry powder blend

Premix of 97.3 wt% of Graphite (China Steel MG12-A) and 2.7 wt% of conductive additive (Super C65) were prepared using a V-blender. Same preparation procedure in example 1 was applied.

Preparation of electrode paste

Utilizing the identical procedure outlined in Example 1, anode electrode films with varying graphite contents (50%, 55%, 60%, and 65% volume) were produced. The extruder settings remained consistent with a screw rotation speed of 70 rpm and an extruder temperature of 25°C throughout the process. Smooth- surfaced anode electrode films were successfully obtained up to a graphite content of 65% volume. For a comprehensive understanding of the rheological properties associated with different graphite contents was illustrated in FIG. 11.

In FIG. 12, a comparison of the viscosities between NCM cathode and graphite anode materials is presented. The analysis reveals that the graphite anode exhibits substantially higher viscosity compared to the NCM cathode. This disparity in viscosity can be attributed to the significantly lower density of graphite (2.223g/cm3) when compared to NCM(4.740 g/cm3). This finding underscores the importance of understanding the material properties, such as density, in relation to viscosity, which can impact the processing and performance of electrode materials in battery manufacturing.

Example 3 : Catholyte Preparation

Preparation of Polymer Electrolyte PEO (P2193: Mw 8,000, Sigma) polymer powder and the lithium salt (LiTFSI) was dry mixed in a planetary mixer (Primix). 200 g of PEO powder and 130 g of LiTFSI were put into the container, and were mixed at 70C for 15 min at the speed of 37 rpm, and additional 1 hour under vacuum, and at 15 rpm for another hour. Transparent lithium salt without air bubbles was obtained.

Preparation of Dry Powder Blend

Premix was obtained at the same procedure of example 1 only except the active material of NCM811 made in POSCO.

Preparation of electrode paste

Using the same procedure in example 1 except the extrusion temperature of 50 °C, the cathode electrode films of various NCM contents (54, 58, 62 vol%) having a nice and smooth surface could be obtained.

Example 4: Anolyte Preparation

Preparation of Polymer Electrolyte

Procedure was the same as that outlined in example 3.

Preparation of Dry Powder Blend

Premix was obtained at the same procedure of example 2 only except for the conductive carbon of LITX50.

Preparation of electrode paste

Using the same procedure in example 1 except the extrusion temperature of 50 °C, the anode electrode films of Graphite contents 65 vol%) having a nice and smooth surface could be obtained.

Example 5: Catholyte Preparation Preparation of PEO lithium salt

Procedure was same as example 3 except for PEO molecular weight 10,000 (PEG10000, Sigma). Transparent lithium salt without air bubbles was obtained.

Preparation of premix of active material and conductive additives Procedure was the same as that outlined in example 3.

Preparation of electrode paste

Using the same procedure in example 3, the cathode electrode films of various NCM contents of 55 and 60vol% having a nice and smooth surface could be obtained.

Example 6 Preparation of Polymer Electrolyte

Procedure was same as example 4 except for PEO molecular weight 10,000 (PEG10000, Sigma). Transparent lithium salt without air bubbles was obtained.

Preparation of Dry Powder Blend

Procedure was same as example 4. Preparation of electrode paste

Using the same procedure in example 4, the cathode electrode films of various NCM contents of 55, 60, and 65 vol% having a nice and smooth surface could be obtained.

Claims

CLAIMS What is claimed is:

1. A solvent-less battery electrode processing method comprising: mixing an active material powder with a conductive carbon powder and a polymer electrolyte dissolved with a salt to form a mixture; and extruding the mixture through a die and/or between rolls to form a thin film.

2. The solvent-less battery electrode processing method of claim 1, wherein the dissolved polymer electrolyte is a solid polymer electrolyte.

3. The solvent-less battery electrode processing method of claim 1, wherein the dissolved polymer electrolyte is a gel-polymer precursor.

4. The solvent-less battery electrode processing method of claim 1, wherein the polymer electrolyte is a solid ceramic electrolyte in a polymer matrix.

5. The solvent-less battery electrode processing method of claim 3, further comprising curing the thin fdm to cross-link the gel-polymer precursor and produce an electrode film.

6. The solvent-less battery electrode processing method of claim 1, wherein the thin film is extruded directly onto a metal foil current collector.

7. A solvent-less battery electrode processing method, comprising: mixing a liquid electrolyte with a low viscosity small molecule gel precursor to formulate a plasticizer; mixing the plasticizer with conductive carbon and active material to produce a paste; and extruding the paste through a die or between rolls or both to form a thin film on a metal foil.

8. A method for manufacturing a high-energy density solid-state battery, wherein the battery comprises a solid-state cathode, a solid-state anode, and a separator, the method comprising: mixing an active material powder with a conductive carbon powder; dissolving a polymer electrolyte with a salt to form a solution; mixing the solution with the mixed powders to form a homogeneous mixture; and extruding the mixture through a die and/or between rolls to produce a smooth thin film.

9. The method of claim 8, wherein the solid-state electrolyte is a solid polymer electrolyte.

10. The method of claim 9, wherein the solid-state electrolyte is a gel-polymer precursor.

11. The method of claim 9, wherein the solid-state electrolyte is a solid ceramic electrolyte in a polymer matrix.

12. The method of claim 9, wherein the thin film is extruded directly onto a metal foil current collector.

13. The method of claim 10, wherein a high molecular weight polymer electrolyte is mixed with plasticizers to form the gel-polymer precursor.

14. The method of claim 10, further comprising curing the thin film to cross-link the gel polymer precursor and produce an electrode film.