Preparation method of modified positive electrode material and lithium ion battery

Abstract

The invention relates to a preparation method of a modified positive electrode material and a lithium ion battery, and the preparation method comprises the following steps: dissolving oxyhalide of zirconium and halide of lithium in water, and uniformly mixing to obtain a mixed solution; uniformly mixing the mixed solution with ternary positive electrode material powder to obtain slurry; then, freezing the slurry with liquid nitrogen, freeze-drying for 12-48 hours under a vacuum condition, annealing for 2-4 hours at 200-400 DEG C in an inert atmosphere, and cooling to obtain an annealed product; and grinding and sieving the annealed product to obtain the modified positive electrode material. According to the invention, in-situ uniform coating of the halide solid electrolyte on the surface of the positive electrode material is realized, a lithium ion transmission path is optimized, additives such as a surfactant and a binder do not need to be introduced, and adverse effects on the performance of the positive electrode material can be avoided.

Description

Technical Field

[0001] The present invention relates to a preparation method of a modified cathode material and a lithium-ion battery, and particularly to a preparation method of a modified cathode material with a halide coating layer and a lithium-ion battery, belonging to the field of lithium-ion batteries. Background Art

[0002] With the rapid development of electric vehicles and energy storage technologies, higher requirements are put forward for the performance of lithium-ion batteries. Ternary cathode materials, such as lithium nickel cobalt manganese oxide (LiNi x Co y Mn 1-x-y O2, 0 < x, y < 1) and lithium nickel cobalt aluminate (LiNi x [[ID=十六]]Co y Al 1-x- y O2, 0 < x, y < 1), etc., have become the research focus and application mainstream of lithium-ion battery cathode materials due to their high energy density and good charge-discharge performance. However, ternary cathode materials still face many challenges in practical applications, especially when applied to solid-state batteries, there are generally problems such as poor interfacial compatibility and low ion conduction efficiency, resulting in poor battery cycle stability and attenuation of rate performance. To solve this problem, coating technology (such as Al2O3, TiO2, ZrO2, etc.) is usually used to modify the surface of cathode materials. However, the traditional coating methods have the following problems: it is difficult to obtain a relatively uniform coating layer by using the mechanical mixing dry coating process, and there is a risk of coating layer shedding; in general, the wet coating process generally requires heating to evaporate the solvent, and high temperature is likely to cause agglomeration or cracking of the coating layer, and there is also a problem of uneven distribution of coating components. At the same time, the rapid evaporation of the solvent may further cause a local concentration gradient, resulting in phase separation between the electrolyte and the cathode material.

[0003] Chinese Patent Application CN201510043316.3 discloses a modification method of a lithium-ion battery cathode material. This method uses low-melting-point aluminum or zirconium salts (mainly including aluminum nitrate, aluminum acetate, zirconium nitrate, zirconium acetate, zirconium oxychloride, etc.) as alkali treatment agents. After mixing the alkali treatment agents with the high-pH lithium-ion battery cathode material evenly, a two-stage sintering process is adopted. After raising the temperature to make the low-melting-point alkali treatment agent melt and fully infiltrate and contact on the surface of the cathode material, the temperature is further raised to make it react fully with the residual alkaline lithium salts in the cathode material to obtain the final product. This patent requires first melting and infiltrating the cathode material with the alkali treatment agent at 75 - 500 °C, and then heating at a high temperature of 600 - 900 °C to decompose the alkali treatment agent. Obviously, its heat treatment process is relatively complex, with high energy consumption, and it is easy to have the problem of uneven coating, which further affects the electrochemical performance of the cathode material.

[0004] Chinese invention patent application CN202210645822.X discloses a cathode material coated with a halide solid electrolyte, its preparation method, and its application. The cathode material includes a ternary cathode material (such as NCM series or NCA series) and a halide solid electrolyte Li₂ZrCl₆ coated on the surface of the ternary cathode material. The preparation method of this cathode material includes the following steps: mixing the halide solid electrolyte Li₂ZrCl₆ with the ternary cathode material and manually grinding them in a mortar to obtain a mixed material; mechanically grinding the mixed material to obtain the halide solid electrolyte coated cathode material. However, this coating process generally suffers from uneven coating layers, easily leading to localized over-coating or incomplete coating, thus affecting the electron / ion transport performance of the material. Macroscopically, the electrochemical performance of the material also exhibits inhomogeneity (such as poor capacity consistency, decreased cycle stability, and rate performance degradation).

[0005] Chinese invention patent application CN116741961A discloses a method for preparing lithium cobalt oxide cathode material. The method includes: S1: weighing lithium chloride and indium chloride separately, dissolving them in deionized water to obtain a precursor solution; S2: weighing lithium cobalt oxide and placing it in the precursor solution, mixing evenly, freezing into a solid, and freeze-drying to obtain lithium cobalt oxide with a coating layer; wherein the coating layer is a halide solid electrolyte Li3InCl6. The cooling temperature of freeze-drying equipment can often only reach around -50℃, limiting the freezing speed. Since lithium cobalt oxide is insoluble in water, before freezing into a solid, the lithium cobalt oxide in the precursor solution is very likely to precipitate and separate, affecting the coating effect. Summary of the Invention

[0006] To address the shortcomings of existing technologies, one objective of this invention is to provide a method for preparing modified cathode materials to achieve better coating modification and obtain modified cathode materials with superior electrochemical performance; another objective of this invention is to provide a lithium-ion battery.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A method for preparing a modified cathode material includes the following steps: S1. Mix zirconium halide, lithium halide, water, and ternary cathode material powder in a ratio of 0.02mol: 0.02-0.06mol: 90-110mL: 35-60g to obtain a slurry; Wherein, the zirconium halide is one or more of ZrOCl2, ZrOCl2·8H2O, ZrOBr2, and ZrOBr2·8H2O; the lithium halide is one or two of LiCl and LiBr. S2. Pour the slurry into a tray, immerse the tray in liquid nitrogen, freeze for 2-4 minutes, and then quickly transfer the tray to a vacuum freeze-drying device. Freeze-dry under vacuum conditions for 12-48 hours, and then anneal at 200-400℃ for 2-4 hours under an inert atmosphere. After cooling, obtain the annealed product. The tray is made of metal. S3. Grind the annealed product and sieve it to obtain the modified cathode material.

[0008] Furthermore, the ternary cathode material powder is a nickel-cobalt-manganese cathode material and / or a nickel-cobalt-aluminum cathode material.

[0009] Furthermore, the particle size of the ternary cathode material powder is 1-20 μm.

[0010] Optionally, the ternary cathode material has a single crystal or polycrystalline structure.

[0011] Optionally, in S1, zirconium halide and lithium halide are first dissolved in water and mixed evenly to obtain a mixed solution; then the mixed solution is mixed evenly with ternary cathode material powder to obtain a slurry.

[0012] Optionally, in S1, zirconium halide, lithium halide, water, and ternary cathode material powder are mixed evenly in a ratio of 0.02mol: 0.03-0.05mol: 95-105mL: 40-55g.

[0013] Furthermore, in S2, during freeze drying, the vacuum degree is controlled to be ≤10 Pa and the freeze drying temperature is controlled to be ≤-50℃.

[0014] Furthermore, in S2, the inert atmosphere is argon or nitrogen protective atmosphere, and the gas flow rate is 50-1000 ml / min, and even further, 150-800 ml / min.

[0015] Furthermore, in S2, the temperature is increased to 200-400℃ at a rate of 2-10℃ / min under an inert atmosphere.

[0016] Furthermore, in S2, annealing is carried out at 250-350℃ for 2.5-3.5 hours under an inert atmosphere.

[0017] Furthermore, in S2, the metal is one or more of stainless steel, aluminum alloy, and copper alloy; preferably, the initial thickness of the slurry in the tray is controlled to be 5-12 mm. This facilitates rapid heat exchange between liquid nitrogen and the slurry; controlling the initial thickness of the slurry in the tray to be thin helps the slurry transform into a solid or semi-solid state in the shortest possible time.

[0018] Furthermore, in S3, it passes through a 200-400 mesh sieve.

[0019] This invention involves first dissolving zirconium halide and lithium halide in water to form a mixed solution, then mixing the ternary cathode material with the mixed solution to form a slurry. The slurry is then placed in a metal tray and immersed in liquid nitrogen. The extremely low temperature of the liquid nitrogen (below -196.56°C) allows for rapid indirect heat exchange between the liquid nitrogen and the slurry in the tray, enabling the solution within the slurry to quickly crystallize and transform into a solid or semi-solid substance. This effectively avoids the possibility of stratification and precipitation of the ternary cathode material powder, ensuring that the ternary material powder is uniformly distributed within the solid or semi-solid substance, preparing for uniform coating. The tray is then quickly transferred to a vacuum freeze-drying apparatus. Through vacuum freeze-drying, uniform coating of Li-Zr-O-halogens on the surface of the ternary cathode material is achieved, significantly improving its interfacial stability and ion transport pathways.

[0020] Based on the same inventive concept, the present invention also provides: a lithium-ion battery, comprising a positive electrode, an electrolyte layer, and a negative electrode stacked sequentially, wherein the electrolyte layer is a polymer solid electrolyte layer, and the active material of the positive electrode is a modified positive electrode material prepared by the preparation method described above.

[0021] Furthermore, the polymer solid electrolyte is one or more of polyvinylidene fluoride (PVDF) based solid electrolyte, polyethylene oxide (PEO) based solid electrolyte, polyacrylonitrile (PAN) based solid electrolyte, and polymethyl methacrylate (PMMA) based solid electrolyte.

[0022] Optionally, the negative electrode sheet is one or more of lithium metal, lithium metal alloy, graphite, silicon-carbon negative electrode, and negative electrode-less current collector.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In this invention, zirconium halide oxide and lithium halide are dissolved in deionized water to form a Lewis acidic Li-Zr-O-halogen structure, which can reduce the residual alkali content on the surface of the ternary cathode material. At the same time, the strong chemical bonding characteristics of Zr-O bond can effectively inhibit the decomposition of polymer electrolyte. When assembled with polymer solid electrolyte, solid battery can significantly improve interface stability and improve the cycle stability of solid battery.

[0024] (2) This invention achieves in-situ uniform coating of halide solid electrolyte on the surface of cathode material through rapid freezing with liquid nitrogen and freeze-drying technology, optimizing the lithium-ion transport path, and eliminating the need for additives such as surfactants and binders, thus avoiding adverse effects on the performance of cathode material. Compared with mechanical ball milling and coating, freeze-drying can achieve more uniform and complete coating; at the same time, compared with direct high-temperature drying, water in freeze-drying directly sublimates in solid form, avoiding component segregation caused by liquid phase migration.

[0025] (3) The preparation method of the present invention is environmentally friendly, without the use of surfactants, binders and other organic reagents, and is green and environmentally friendly.

[0026] (4) The present invention has significant advantages in reducing side reactions between the cathode material and the electrolyte and improving the lithium-ion transport path, and is especially suitable for polymer-based solid-state batteries. Attached Figure Description

[0027] Figure 1 The images show a comparison of SEM images of the coating materials prepared in Example 1 and Comparative Example 1 of the present invention.

[0028] Figure 2 The image shown is an XPS image of the coating material prepared in Example 1 of the present invention, wherein the unit of relative strength is au.

[0029] Figure 3 The graph shows the rate performance of the coin cells assembled in Example 1 and Comparative Examples 1-3 of the present invention at room temperature and 0.1C-5C.

[0030] Figure 4 The graphs show the first charge-discharge curves of the coin cells assembled in Embodiment 1 and Comparative Examples 1-3 of the present invention at room temperature and 1C cycle.

[0031] Figure 5 The graph shows the cycle performance of the coin cells assembled in Example 1 and Comparative Examples 1-3 of the present invention at room temperature and 1C rate. Detailed Implementation

[0032] The present invention will be described in detail below with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other. In all embodiments and comparative examples, the purity of zirconium oxychloride (ZrOCl2) used is ≥99%, the purity of zirconium chloride is ≥99.5%, and the purity of lithium chloride is ≥99%. Unless otherwise specified, the relevant percentages refer to mass percentages.

[0033] Example 1 In this embodiment, the preparation method of the modified cathode material powder includes the following steps: (1) Weigh 6.44g of zirconium oxychloride (ZrOCl2·8H2O) and 1.70g of lithium chloride (the molar ratio of zirconium oxychloride to lithium chloride is 1:2), add them to 100mL of deionized water, mix well, and obtain a mixed solution; (2) Add 47.32g of NCM811 (LiNi) to the mixed solution obtained in step (1). 0.8 Co 0.1 Mn 0.1 O2 powder, stir for 2 hours to form a uniform slurry; At this point, the ratio of zirconium oxychloride (ZrOCl2·8H2O), lithium chloride, water, and NCM811 in the slurry is 0.02mol:0.04mol:100mL:47.32g.

[0034] (3) Pour the slurry into the tray (made of 304 stainless steel), control the initial thickness of the slurry in the tray to be 10 mm, then immerse the tray containing the slurry in liquid nitrogen, freeze for 3 min, and then quickly transfer the tray to a vacuum freeze-drying device. After freeze-drying for 24 h under vacuum of 5 Pa and -50 °C, the dry cathode material coated with Li-Zr-O-Cl can be obtained.

[0035] The initial thickness of the slurry in the tray is 10mm. During immersion, the liquid nitrogen level is controlled to be below the top of the tray.

[0036] (4) The positive electrode material coated with Li-Zr-O-Cl was heated to 300℃ at 5℃ / min under argon atmosphere and annealed for 3 hours. Then it was naturally cooled under the condition of maintaining an inert atmosphere to obtain the annealed product. The argon flow rate was controlled at 400 mL / min. (5) Post-processing: The annealed product is ground and then passed through a 300-mesh sieve to obtain a uniformly coated modified cathode material powder.

[0037] The SEM image of the modified cathode material powder is shown below. Figure 1 As shown in (a), the surface elemental analysis diagram is as follows: Figure 2 As shown, a uniformly distributed coating layer is clearly formed on the surface of the cathode material, and the coating layer has a Li-Zr-O-Cl structure. The pH of the modified cathode material powder was determined by acid-base titration. The pH of the cathode material decreased from 12.25 to 11.48. The total lithium impurity content of the modified cathode material decreased from 0.324% to 0.069%, significantly reducing the content of alkaline substances on the surface. The total lithium impurity content refers to the mass content of lithium in the alkaline impurities Li₂CO₃ and LiOH.

[0038] The lithium metal solid-state battery was assembled as follows: the battery was assembled in the order of positive electrode case, positive electrode sheet, solid electrolyte, lithium sheet (15.6 mm × 0.45 mm) and negative electrode case, and room temperature impedance and charge-discharge performance were tested.

[0039] The preparation method of the positive electrode sheet is as follows: the modified positive electrode material powder, conductive carbon black (Super P) and binder (polyvinylidene fluoride, abbreviated as PVDF) are mixed evenly in a mass ratio of 8:1:1 and dissolved in NMP to form a positive electrode slurry with a solid content of 50wt%; the positive electrode slurry is then coated on aluminum foil and dried in a vacuum drying oven at 80℃ for 24h to obtain the positive electrode sheet.

[0040] Negative electrode: A 450μm thick lithium metal sheet is used as the negative electrode.

[0041] Solid electrolyte: A polyvinylidene fluoride (PVDF)-based solid electrolyte was selected. This solid electrolyte uses PVDF-hexafluoropropylene (PVDF-HFP) as the polymer matrix, and incorporates lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as the lithium salt, barium titanate (BaTiO3) as the inorganic filler, and N,N-dimethylformamide (DMF) as the solvent through solution blending. The electrolyte membrane is prepared by casting and has a thickness of 60 μm. The ratio of polymer matrix, lithium salt, inorganic filler, and solvent is 10 g: 10 g: 2 g: 50 mL.

[0042] Electrochemical testing showed that the lithium metal solid-state battery exhibited an interfacial impedance of 20.5 Ω, an initial coulombic efficiency of 90.6% at 0.1C, a discharge capacity of 125.1 mAh / g at 5C, and a capacity retention of 92% after 500 cycles at 1C, demonstrating excellent electrochemical performance. The first-cycle impedance at room temperature was measured using an AC impedance spectroscopy (EIS) tester on a Chenhua CH760e electrochemical workstation. Cycling and rate performance tests were conducted using a Xinwei BTS-5V10mA testing system.

[0043] Comparative Example 1 Repeat Example 1, except that in step (1), zirconium chloride (ZrCl4) is used instead of ZrOCl2·8H2O. Weigh 4.67g of ZrCl4 and 1.70g of lithium chloride (the molar ratio of zirconium chloride to lithium chloride is 1:2) and add them to 100mL of deionized water.

[0044] Comparative Example 2 In this comparative example, the preparation method of the modified cathode material powder includes the following steps: (1) Weigh out 6.44g of zirconium oxychloride (ZrOCl2·8H2O), 1.70g of lithium chloride (the molar ratio of zirconium oxychloride to lithium chloride is 1:2), and 47.32g of NCM811 (LiNi) respectively. 0.8 Co 0.1 Mn 0.1 O2 powder is added to a zirconia ball mill jar, and 10mm diameter zirconia grinding balls are placed inside the jar. The jar is then sealed and placed in a ball mill for mechanical ball milling for 4 hours at a speed of 250 rpm. After the ball milling time is completed, the jar is removed, the sealed lid is opened, and the mixed coated material is obtained. (2) The mixed coating material was annealed at 300°C for 3 hours under an argon atmosphere at a rate of 5°C / min, and then cooled naturally under an inert atmosphere to obtain the annealed product; wherein the argon flow rate was controlled at 400 mL / min. (3) Post-processing: The annealed product is ground and then passed through a 300-mesh sieve to obtain modified cathode material powder.

[0045] The following steps are the same as in Example 1.

[0046] The SEM image of the modified cathode material powder is shown below. Figure 1 As shown in (b), a coating layer is formed on the surface of the positive electrode material, but the uniformity of the coating layer is significantly worse than that of Example 1.

[0047] Comparative Example 3 In this comparative example, the preparation method of the modified cathode material powder includes the following steps: (1) Weigh 6.44g of zirconium oxychloride (ZrOCl2·8H2O) and 1.70g of lithium chloride (the molar ratio of zirconium oxychloride to lithium chloride is 1:2), add them to 100mL of deionized water, mix well, and obtain a mixed solution; (2) Add 47.32g of NCM811 (LiNi) to the mixed solution in step (1). 0.8 Co 0.1 Mn 0.1 O2 powder, stir for 2 hours to form a uniform slurry; (3) The slurry was placed in a vacuum drying oven, the vacuum degree was maintained at 50 Pa, the drying temperature was 105 °C, and the drying time was controlled at 24 h, and then the coated positive electrode material was obtained. (4) The coated cathode material was annealed at 300°C for 3 hours under an argon atmosphere at a rate of 5°C / min, and then cooled naturally under an inert atmosphere to obtain the annealed product; wherein the argon flow rate was controlled at 400 mL / min. (5) Post-processing: The annealed product is ground and then passed through a 300-mesh sieve to obtain modified cathode material powder coated with high temperature drying.

[0048] The following steps are the same as in Example 1.

[0049] Comparative Example 4 Repeat Example 1, except that in step (3), the liquid nitrogen soaking step is omitted, and the tray containing the slurry is directly transferred to the vacuum freeze-drying device for freeze-drying.

[0050] Comparative Example 5 Repeat Example 1, except that in step (1), 6.44g of zirconium oxychloride (ZrOCl2·8H2O) and 0.68g of lithium chloride (the molar ratio of zirconium oxychloride and lithium chloride is 1:0.8) are weighed and added to 100mL of deionized water.

[0051] Example 2 Repeat Example 1, except that in step (1), 6.44g of zirconium oxychloride (ZrOCl2·8H2O) and 0.85g of lithium chloride (the molar ratio of zirconium oxychloride and lithium chloride is 1:1) are weighed and added to 100mL of deionized water.

[0052] Example 3 Repeat Example 1, except that in step (1), 6.44g of zirconium oxychloride (ZrOCl2·8H2O) and 2.55g of lithium chloride (the molar ratio of zirconium oxychloride and lithium chloride is 1:3) are weighed and added to 100mL of deionized water.

[0053] Comparative Example 6 Repeat Example 1, except that in step (1), 6.44g of zirconium oxychloride (ZrOCl2·8H2O) and 2.72g of lithium chloride (the molar ratio of zirconium oxychloride to lithium chloride is 1:3.2) are weighed and added to 100mL of deionized water.

[0054] Table 1 Performance test results of each embodiment and comparative example

[0055] The comparison shows that replacing ZrOCl2·8H2O with zirconium chloride (ZrCl4), using mechanical ball milling for mixing and coating, or high-temperature drying of the slurry to achieve coating results in increased battery impedance, and a significant decrease in initial coulombic efficiency, charge and discharge capacity, and cycle performance. This indicates that the Li-Zr-O-Cl coated dry cathode material obtained by the "liquid nitrogen rapid freezing + freeze drying" method of this invention has superior performance.

[0056] Referring to Example 1 and Comparative Example 4, when the liquid nitrogen rapid freezing step is omitted and only freeze-drying is used to treat the slurry, the performance of the final assembled battery is significantly reduced. The possible reason is that the freeze-drying temperature only reaches -50°C, and the slurry still needs a long time to crystallize and solidify. Before the slurry solidifies, some NCM811 powder has already deposited at the bottom of the tray, resulting in uneven coating and affecting the final performance.

[0057] Referring to Examples 1-3 and Comparative Examples 5-6, controlling the ratio of zirconium oxychloride and lithium chloride within a specific range helps to obtain better impedance, initial coulombic efficiency, charge and discharge capacity, and cycle performance indicators.

[0058] The above embodiments should be understood as being used only to illustrate the present invention more clearly, and not to limit the scope of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope defined by the appended claims.

Claims

1. A method for preparing a modified cathode material, characterized in that, Includes the following steps: S1. Mix zirconium halide, lithium halide, water, and ternary cathode material powder in a ratio of 0.02mol: 0.02-0.06mol: 90-110mL: 35-60g to obtain a slurry; Wherein, the zirconium halide is one or more of ZrOCl2, ZrOCl2·8H2O, ZrOBr2, and ZrOBr2·8H2O; the lithium halide is one or two of LiCl and LiBr. S2. Pour the slurry into a tray, immerse the tray in liquid nitrogen, freeze for 2-4 minutes, and then quickly transfer the tray to a vacuum freeze-drying device. Freeze-dry under vacuum conditions for 12-48 hours, and then anneal at 200-400℃ for 2-4 hours under an inert atmosphere. After cooling, obtain the annealed product. The tray is made of metal. S3. Grind the annealed product and sieve it to obtain the modified cathode material.

2. The preparation method according to claim 1, characterized in that, The ternary cathode material powder is a nickel-cobalt-manganese cathode material and / or a nickel-cobalt-aluminum cathode material.

3. The preparation method according to claim 1, characterized in that, The particle size of the ternary cathode material powder is 1-20 μm.

4. The preparation method according to claim 1, characterized in that, In S1, zirconium halide and lithium halide are first dissolved in water and mixed evenly to obtain a mixed solution; then the mixed solution is mixed evenly with ternary cathode material powder to obtain a slurry.

5. The preparation method according to claim 1, characterized in that, In S2, during freeze drying, the vacuum degree is controlled to be ≤10Pa and the freeze drying temperature is controlled to be ≤-50℃.

6. The preparation method according to any one of claims 1-5, characterized in that, In S2, the inert atmosphere is argon or nitrogen, and the gas flow rate is 50-1000 ml / min.

7. The preparation method according to any one of claims 1-5, characterized in that, In S2, annealing is carried out at 250-350℃ for 2.5-3.5 hours under an inert atmosphere.

8. The preparation method according to any one of claims 1-5, characterized in that, In S2, the metal is one or more of stainless steel, aluminum alloy, and copper alloy; preferably, the initial thickness of the slurry in the tray is controlled to be 5-12 mm.

9. A lithium-ion battery, comprising a positive electrode, an electrolyte layer, and a negative electrode stacked sequentially, wherein the electrolyte layer is a polymer solid electrolyte layer, characterized in that, The active material of the positive electrode sheet is a modified positive electrode material prepared by the preparation method described in any one of claims 1-8.

10. The lithium-ion battery according to claim 9, characterized in that, The polymer solid electrolyte is one or more of polyvinylidene fluoride solid electrolyte, polyoxyethylene solid electrolyte, polyacrylonitrile-based solid electrolyte, and polymethyl methacrylate-based solid electrolyte.

Images