Polymer solid electrolyte and all-solid-state battery comprising same

Abstract

The present invention relates to a polymer solid electrolyte comprising: an ion-conductive polymer; organic ionic plastic crystals containing imidazolium; and a lithium salt. The polymer solid electrolyte according to an aspect can simultaneously achieve excellent ion conductivity and electrochemical stability.

Description

Polymer solid electrolyte and all-solid-state battery containing the same

[0001] The present disclosure relates to a polymer solid electrolyte and an all-solid-state battery including the same.

[0002] Recently, with the demand for the development of lithium batteries with both improved energy density and safety, all-solid-state batteries using solid electrolytes that have a low risk of fire, no electrolyte leakage issues, and do not require separators are attracting attention as next-generation batteries.

[0003] Solid electrolytes can be categorized into polymer solid electrolytes and inorganic solid electrolytes based on their materials. Polymer solid electrolytes offer advantages such as flexibility, lightness, and processability. However, compared to conventional liquid electrolytes and inorganic solid electrolytes, polymer solid electrolytes suffer from lower ionic conductivity and lithium ion yield. Various strategies, such as the introduction of inorganic fillers and metal-organic frameworks, have been devised to address these issues. However, achieving the ionic conductivity required for commercialization remains challenging.

[0004] One aspect of the present invention is to provide a polymer solid electrolyte capable of simultaneously achieving excellent ionic conductivity and electrochemical stability, and a method for producing the same.

[0005] Another aspect of the present invention provides an all-solid-state battery comprising the polymer solid electrolyte.

[0006] One aspect of the present invention provides a polymer solid electrolyte comprising an ion conductive polymer, an organic ionic plastic crystal containing imidazolium, and a lithium salt.

[0007] The organic ionic plastic crystal containing the above imidazolium can be in a solid state at room temperature.

[0008] The above organic ionic plastic crystal may be represented by the following chemical formula 1.

[0009] [Chemical Formula 1]

[0010]

[0011] (In the above chemical formula 1,

[0012] R1 to R3 are each independently (C1-C7) alkyl,

[0013] X - is Cl - , Br - , I - , BF4 - or PF6 - am.)

[0014] The above organic ionic plastic crystal may be represented by the following chemical formula 1-1.

[0015] [Chemical Formula 1-1]

[0016]

[0017] The organic ionic plastic crystals may be included in an amount of 0.5 to 5 parts by weight per 100 parts by weight of the ion conductive polymer.

[0018] The above lithium salt and organic ionic plastic crystals may be included in a weight ratio of 1:0.1 to 1.

[0019] The above ion-conducting polymer may be a polyalkylene oxide polymer.

[0020] The above lithium salt may contain an imide anion.

[0021] Another aspect of the present invention provides an all-solid-state battery comprising a positive electrode, the polymer solid electrolyte, and a negative electrode.

[0022] The above negative electrode may include a negative electrode current collector and a negative electrode active material layer.

[0023] Another aspect of the present invention provides a method for producing a polymer solid electrolyte, comprising the steps of: (A) preparing a mixed solution by mixing an organic ionic plastic crystal containing imidazolium and a lithium salt in an organic solvent; (B) preparing a polymer solid electrolyte slurry by adding an ion conductive polymer to the mixed solution and mixing it; and (C) applying the polymer solid electrolyte slurry to a substrate, drying it, and applying heat thereto to obtain a polymer solid electrolyte.

[0024] An all-solid-state battery employing a polymer solid electrolyte according to one aspect of the present invention can satisfy both excellent battery performance and life characteristics.

[0025] Specifically, the polymer solid electrolyte according to one aspect has a commercially viable level of ionic conductivity, for example, 1.0Х10 at room temperature. 3 The above-mentioned excellent ionic conductivity can be realized. In addition, the polymer solid electrolyte according to one embodiment also has excellent stability and compatibility with a lithium metal anode, and an all-solid-state battery employing the polymer solid electrolyte and lithium metal anode according to one embodiment has excellent life characteristics with a capacity retention rate of 99.7% or more even after 300 cycles. Furthermore, the polymer solid electrolyte according to one embodiment not only has excellent ionic conductivity and stability, but also ensures flexibility, so it has the advantage of being applicable to devices.

[0026] Figure 1 illustrates the results of analyzing the life characteristics of an all-solid-state battery according to Example 2.

[0027] Unless otherwise defined herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0028] As used herein, the singular forms may be intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0029] Throughout this specification, the terms "comprises," "includes," "contains," or "has" a component, unless specifically stated to the contrary, do not exclude other components, but rather may include other components, and do not exclude additional unrecited elements, materials, or processes.

[0030] The numerical ranges used herein include the lower and upper limits and all values ​​within that range, increments logically derived from the shape and width of the defined range, all doubly defined values, and all possible combinations of the upper and lower limits of numerical ranges defined in different shapes. Unless otherwise specified herein, values ​​outside the defined range that may arise due to experimental error or rounding of values ​​are also included in the defined numerical range.

[0031] Unless otherwise specified herein, “about” may be considered a value within 30%, 25%, 20%, 15%, 10% or 5% of the stated value.

[0032] Below, the present disclosure will be described in detail. However, this is merely exemplary and the present disclosure is not limited to the specific embodiments described as examples.

[0033] One aspect of the present invention provides a polymer solid electrolyte capable of achieving excellent ionic conductivity and electrochemical stability.

[0034] Specifically, the polymer solid electrolyte according to one aspect may include an ion-conducting polymer, an organic ionic plastic crystal including imidazolium, and a lithium salt.

[0035] Here, organic ionic plastic crystal (OIPC) refers to an ionic organic compound characterized by a solid phase having a plastic crystal at room temperature (25℃), exhibiting very soft characteristics in the solid phase, and is a substance that exhibits a solid-solid phase transition by changing the crystal phase when the temperature changes below the melting point.

[0036] The organic ionic plastic crystal containing the above imidazolium may contain an imidazolium cation and a counter anion. The counter anion is not limited as long as it combines with the imidazolium cation to make the plastic crystal in a solid state at room temperature, and for example, Cl - , Br - , I - , BF4 - or PF6 - It could be.

[0037] Melting point (T) of the organic ionic plastic crystal containing the above imidazolium m ) may be 100°C or higher, 150°C or higher, or 100°C to 300°C, or 150°C to 300°C, or 200 to 300°C.

[0038] Specifically, the organic ionic plastic crystal can be represented by the following chemical formula 1.

[0039] [Chemical Formula 1]

[0040]

[0041] (In the above chemical formula 1,

[0042] R1 to R3 are each independently (C1-C7) alkyl,

[0043] X - is Cl - , Br - , I - , BF4 - or PF6 - am.)

[0044] For example, R1 and R2 can each independently be (C1-C4)alkyl, methyl or ethyl.

[0045] For example, R1 and R2 are the same and can be (C1-C4)alkyl, methyl or ethyl.

[0046] The above organic ionic plastic crystal may be, for example, represented by the following chemical formula 1-1.

[0047] [Chemical Formula 1-1]

[0048]

[0049] The organic ionic plastic crystals may be included in an amount of 0.5 parts by weight or more, or 1 part by weight or more, or 1.5 parts by weight or more, or 10 parts by weight or less, or 5 parts by weight or less, based on 100 parts by weight of the ion conductive polymer, and specifically, may be included in an amount of 0.5 to 5 parts by weight, or 1 to 5 parts by weight, or 1 to 3 parts by weight, and may include all possible combinations of the upper and lower limits of the above numerical range. When the content within the above numerical range is satisfied, the ion conductivity and stability of the polymer solid separation membrane can be further improved in the future.

[0050] The above lithium salt and organic ionic plastic crystals may be included in a weight ratio of 1:0.1 to 1, or a weight ratio of 1:0.1 to 0.8, or a weight ratio of 1:0.1 to 0.5.

[0051] The above ion-conducting polymer is not particularly limited as long as it is commonly used in the relevant technical field, but may be, for example, a polyalkylene oxide-based polymer. Specifically, the polyalkylene oxide polymer may include, but is not limited to, polyethylene oxide, polypropylene oxide, polybutylene oxide, polyethylene oxide-polypropylene oxide blend, polyethylene oxide-polybutylene oxide blend, polyethylene oxide-polypropylene oxide-polybutylene oxide blend, polyethylene oxide-polypropylene oxide block copolymer, polyethylene oxide-polybutylene oxide block copolymer, polyethylene oxide-polypropylene oxide-polybutylene oxide block copolymer, polybutylene oxide-polyethylene oxide-polybutylene oxide block copolymer, polyethylene oxide-polybutylene oxide-polyethylene oxide block copolymer, polymethyl methacrylate grafted with polyethylene oxide (PEO grafted PMMA), polymethyl methacrylate grafted with polypropylene oxide (PPO grafted PMMA), and polymethyl methacrylate grafted with polybutylene oxide (PBO grafted PMMA). It can be selected from the group consisting of PMMA).

[0052] The above ion-conducting polymer may be a linear polymer, a branched polymer or a network polymer, and specifically, may be a linear polymer, and more preferably, may be a polyethylene oxide (PEO) linear polymer.

[0053] The weight average molecular weight of the above ion conductive polymer may be 300,000 g / mol to 1,000,000 g / mol, or 400,000 g / mol to 1,000,000 g / mol.

[0054] The above lithium salt is not particularly limited as long as it is commonly used in the relevant technical field, but for example, LiSCN, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiPF3(C2F5)3, LiCF3SO3, LiAsF6, LiSbF6, LiClO 4, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiPF6, LiPF5(CF3), LiPF5(C2F5), LiPF5(C3F7), LiPF4(CF3)2, LiPF4(CF3)(C2F5), LiPF3(CF3)3, LiPF3(CF2CF3)3, LiPF4(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, It may be one or more selected from LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2), and LiN(SO2C2F5)2.

[0055] Specifically, the lithium salt may include an imide anion, and may be, for example, one or more selected from lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2), and LiN(SO2C2F5)2, and more specifically, may be LiTFSI.

[0056] According to one aspect, a polymer solid electrolyte can be manufactured by including the steps of: (A) preparing a mixed solution by mixing an organic ionic plastic crystal containing imidazolium and a lithium salt in an organic solvent; (B) preparing a polymer solid electrolyte slurry by adding an ion conductive polymer to the mixed solution and mixing it; and (C) applying the polymer solid electrolyte slurry to a substrate, drying it, and applying heat to obtain a polymer solid electrolyte.

[0057] Another aspect of the present invention provides an all-solid-state battery comprising the polymer solid electrolyte.

[0058] Hereinafter, an all-solid-state battery according to one embodiment will be described. However, it is to be understood that the all-solid-state battery can be manufactured in a structure known in the art using conventional manufacturing methods and materials in the art, except that it includes the polymer solid electrolyte according to one embodiment.

[0059] An all-solid-state battery according to one embodiment may include a positive electrode, a solid electrolyte, and a negative electrode, wherein the solid electrolyte includes a polymer solid electrolyte according to one embodiment, and the thickness of the polymer solid electrolyte may be 10 to 200 μm, or 30 to 200 μm, or 50 to 200 μm.

[0060] The above positive electrode may include a positive electrode collector and a positive electrode active material layer formed on the positive electrode collector.

[0061] Non-limiting examples of the positive electrode current collector may include a foil made of aluminum, nickel, or a combination thereof, and the positive electrode active material layer may include a positive electrode active material, a binder, a conductive material, a dispersing agent, etc., as needed.

[0062] The above cathode active material may be a conventional cathode active material used in this technical field, and non-limiting examples thereof include lithium cobalt oxide composite oxide (LiCoO2), spinel crystal type lithium manganese oxide composite oxide (LiMn2O4), lithium manganese oxide composite oxide (LiMnO2), lithium nickel oxide composite oxide (LiNiO2), and lithium iron phosphate (LiFePO4; LFP), lithium manganese phosphate (LiMnPO4), lithium cobalt phosphate (LiCoPO4), lithium iron pyrophosphate (iron pyrophosphate; Li2FeP2O7), lithium niobate composite oxide (LiNbO2), lithium ferrate composite oxide (LiFeO2), lithium magnesium composite oxide (LiMgO2), lithium cuprate composite oxide (LiCuO2), lithium zinc composite oxide (LiZnO2), lithium molybdate composite oxide (LiMoO2), lithium tantalate composite oxide (LiTaO2), lithium tungstate composite oxide (LiWO2), lithium permanganate nickel cobalt composite oxide (xLi2MnO3(1-x)LiMn1-y-zNiyCozO2), lithium nickel cobalt aluminum composite oxide (LiNi 0.8 Co 0.15 Al 0.05 O2), lithium nickel cobalt manganese composite oxide (LiNi 0.33 Co 0.33 Mn 0.33 O2, LiNi 0.4 Co 0.2 Mn 0.4 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.7 Co 0.15 Mn 0.15 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2), manganese nickel oxide (LiNi 0.5 Mn 1.5O4) etc., and specifically lithium iron phosphate can be used, but is not limited thereto.

[0063] The conductive material may include, but is not limited to, carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, etc.; conductive fibers such as carbon fibers and metal fibers; metal powders such as fluorinated carbon, aluminum, and nickel powders; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives, but is not particularly limited as long as it has conductivity and does not cause chemical changes in the battery.

[0064] The above binder polymer may include one or two or more selected from the group consisting of nitrile butadiene rubber, polybutadiene rubber, polyethylene glycol, polyacrylonitrile, polyvinyl chloride, polymethyl methacrylate, polypropylene oxide, polydimethylsiloxane, polyvinylidene fluoride, polyvinylidene carbonate, and polyvinylpyrrolidinone.

[0065] The above negative electrode may include a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector.

[0066] Non-limiting examples of the negative electrode current collector may be selected from a foil made of copper, gold, nickel, or a copper alloy or a combination thereof. The negative electrode active material layer may be any one or two or more selected from the group consisting of any one carbon selected from soft carbon, hard carbon, artificial graphite, natural graphite, expanded graphite, carbon fiber, non-graphitizable carbon, carbon black, carbon nanotubes, acetylene black, Ketjen black, graphene, fullerene, activated carbon, and meso carbon microbeads; any one metal selected from silicon, tin, lithium, aluminum, silver, bismuth, indium, germanium, lead, platinum, titanium, zinc, manganese, cadmium, cerium, copper, cobalt, nickel, and iron; an alloy comprising two or more of the above metals; and an oxide of one or more of the above metals; and preferably, lithium metal, but is not limited thereto.

[0067] Lithium metal anodes can satisfy high energy densities due to their high specific capacity and low reduction potential. However, batteries employing lithium metal as the anode have suffered from the problem of dendrite growth on the electrode surface during the charge / discharge process, which accelerates the decline in reversible capacity. A polymer solid electrolyte according to one embodiment has excellent compatibility with lithium metal and can realize excellent cycle life characteristics when lithium metal is employed as the anode, thereby solving the problems of the prior art described above.

[0068] Hereinafter, the above-described implementation examples will be described in more detail through examples. However, the following examples are for illustrative purposes only and do not limit the scope of the rights.

[0069] [Example 1]

[0070] Preparation of polymer solid electrolytes

[0071] Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) 0.39 g, 1-butyl-2,3-dimethylimidazolium bromide (BMI-Br, chemical formula 1-1) 0.0495 g were added to 15 mL of acetonitrile (ACN) and stirred at room temperature (25°C) for 2 hours, and polyethylene oxide (PEO, M w =600,000 g / mol) was added and stirred for 24 hours to prepare a polymer solid electrolyte slurry. After that, the polymer solid electrolyte slurry was applied to a Teflon dish and dried in a glove box for 24 hours, and then heated at 60°C for 12 hours using a hot plate to obtain a polymer solid electrolyte with a thickness of 108 μm.

[0072] Manufacturing of all-solid-state batteries

[0073] A cathode slurry was prepared by adding lithium iron phosphate (LiFePO4, LFP) / carbon nanotubes / polyvinylidene fluoride (PVDF) / LiTFSI / PEO to N-methylpyrrolidone at a weight ratio of 75:8:1:4:3:9 so that the cathode material content was 75%. The cathode slurry was applied to a 17 μm thick carbon (C)-coated aluminum (Al) thin film using a doctor blade, and then dried with hot air at 90°C for 2 hours and then vacuum-dried at 70°C for 12 hours to obtain a cathode having a 30 μm thick cathode active material layer. An all-solid-state battery was prepared by laminating the polymer solid electrolyte sheet between the cathode obtained above and a lithium metal anode having a thickness of 50 μm.

[0074] [Examples 2 to 4]

[0075] When manufacturing a polymer solid electrolyte, the same procedure as Example 1 was followed, except that the BMI-Br content was changed to 0.099 g (Example 2), 0.1485 g (Example 3), and 0.198 g (Example 4).

[0076] [Comparative Example 1]

[0077] When manufacturing a polymer solid electrolyte, the same procedure as Example 1 was followed, except that BMI-Br was not added.

[0078] [Comparative Example 2]

[0079] The same procedure as in Example 1 was followed, except that N,N-diethylpyrrolidinium bis(trifluorosulfonyl)imide (C2epyr-FSI) was used instead of BMI-Br in the preparation of the polymer solid electrolyte.

[0080]

[0081] [Comparative Example 3]

[0082] The same procedure as in Example 1 was followed, except that 1-butyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide (BMI-TFSI), an ionic liquid, was used instead of BMI-Br when manufacturing a polymer solid electrolyte.

[0083]

[0084] <Evaluation example>

[0085] Evaluation 1. Evaluation of ionic conductivity of polymer solid electrolytes

[0086] The polymer solid electrolytes manufactured in the above examples and comparative examples were placed between stainless steel to manufacture an ionic conductivity measurement cell, and the ionic conductivity of the polymer solid electrolyte was measured according to the temperature (30℃, 40℃, 50℃, 60℃, 70℃). Based on EIS (Electrochemical Impedance Spectroscopy) analysis, the impedance was measured by applying an AC amplitude of 5 mV and a frequency range of 50 mHz to 2 MHz at each temperature condition, and the ionic conductivity was calculated according to the temperature. The results are shown in Table 1 below.

[0087] Ionic conductivity (S / cm) 30℃ 40℃ 50℃ 60℃ 70℃ Example 11.10×10 *?*3 2.88×10 *?*3 8.10×10 *?*3 8.19×10*?*3 1.01×10 *?*2 Example 22.34×10 *?*3 4.10×10 *?*3 1.35×10 *?*2 1.35×10 *?*2 1.34×10 *?*2 Example 31.66×10 *?*3 3.16×10 *?*3 1.48×10 *?*2 1.07×10 *?*2 9.66×10 *?*3 Example 41.04×10 *?*3 2.80×10 *?*3 1.24×10 *?*2 1.20×10 *?*2 9.72×10 *?*3 Comparative example 11.97×10 *?*5 7.37×10 *?*5 1.56×10 *?*4 3.95×10 *?*4 5.53×10 *?*4

[0088] Referring to Table 1 above, it can be seen that the polymer solid electrolytes of Examples 1 to 4 have ionic conductivities that are about 100 times higher than the solid electrolyte of Comparative Example 1, to which BMI-Br was not introduced. In addition, it was confirmed that Comparative Examples 2 and 3 have significantly lower ionic conductivities than the polymer solid electrolyte of the Example, despite using an ionic compound such as BMI-Br of the Example.

[0089] Evaluation 2. Life Characteristics Evaluation

[0090] The life characteristics of the all-solid-state batteries manufactured in Example 2 and Comparative Examples 2 and 3 were analyzed. The initial discharge capacity (C1) was observed at a current of 1 C (= 1 mA / cm2) in a voltage range of 2.5 to 3.8 V under temperature conditions of 60℃, and the charge / discharge number was repeated 300 times under a current of 1 C (= 1 mA / cm2) to measure the 300th discharge capacity (C2), and the capacity retention ratio (C2 / C1 X100) was calculated to observe the life characteristics. The results are shown in Fig. 1 and Table 2 below.

[0091] Capacity retention rate Example 299.7% Comparative example 290.6% Comparative example 386.2% (@150cycle)

[0092] As shown in FIG. 1 and Table 2 above, the all-solid-state battery according to Example 2 was confirmed to have excellent life characteristics with a capacity retention rate of 99.7% even after 300 cycles under temperature conditions of 60°C. On the other hand, it can be seen that the life characteristics are significantly deteriorated compared to the all-solid-state battery of the Example despite the use of the ionic compounds of Comparative Examples 2 and 3. In particular, Comparative Example 3, which uses an ionic compound of an ionic liquid rather than an organic ionic plastic crystal, had a capacity retention rate of 85.2% even after 150 cycles, showing significantly deteriorated life characteristics compared to the all-solid-state battery according to one aspect of the present invention.

[0093] In summary, it can be seen that the polymer solid electrolyte according to one aspect of the present invention can sufficiently implement the level of ionic conductivity required for commercialization, and also has excellent compatibility with a lithium metal negative electrode, so that even when lithium metal is used as the negative electrode, it has excellent life characteristics.

[0094] As described above, the present invention has been described by limited embodiments, but these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains can make various modifications and variations based on this description.

[0095] Therefore, the idea of ​​the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the claims described below as well as the claims are considered to fall within the scope of the idea of ​​the present invention.

Claims

1. A polymer solid electrolyte comprising an ion-conducting polymer, an organic ionic plastic crystal containing imidazolium, and a lithium salt.

2. In paragraph 1, The organic ionic plastic crystal containing the above imidazolium is a polymer solid electrolyte that is in a solid state at room temperature.

3. In paragraph 2, A polymer solid electrolyte, wherein the organic ionic plastic crystal is represented by the following chemical formula 1. [Chemical Formula 1] In the above chemical formula 1, R1 to R3 are each independently (C1-C7) alkyl, X - is Cl - , Br - , I - , BF4 - or PF6 - am.

4. In paragraph 3, The above organic ionic plastic crystal is a polymer solid electrolyte represented by the following chemical formula 1-1. [Chemical Formula 1-1] 5. In paragraph 1, A polymer solid electrolyte, wherein the organic ionic plastic crystals are included in an amount of 0.5 to 5 parts by weight based on 100 parts by weight of the ion conductive polymer.

6. In paragraph 1, A polymer solid electrolyte, wherein the lithium salt and organic ionic plastic crystals are included in a weight ratio of 1:0.1 to 1.

7. In paragraph 1, The above ion-conducting polymer is a polymer solid electrolyte that is a polyalkylene oxide polymer.

8. In paragraph 1, A polymer solid electrolyte wherein the lithium salt contains an imide anion.

9. An all-solid-state battery comprising a cathode, a polymer solid electrolyte selected from any one of claims 1 to 8, and a cathode.

10. In paragraph 9, An all-solid-state battery, wherein the negative electrode comprises a negative current collector and a negative active material layer, and the negative active material layer is lithium metal. 11.(A) A step of preparing a mixed solution by mixing an organic ionic plastic crystal containing imidazolium and a lithium salt in an organic solvent; (B) a step of preparing a polymer solid electrolyte slurry by adding an ion conductive polymer to the above mixed solution and mixing; and (C) A method for producing a polymer solid electrolyte, comprising the step of applying the polymer solid electrolyte slurry to a substrate, drying it, and applying heat to obtain a polymer solid electrolyte.

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