A Preparation Method and Application of a Solid Electrolyte Membrane

Abstract

The present invention provides a method for preparing a solid electrolyte membrane and its application, belonging to the technical field of energy materials, which includes the following steps: Mix lithium chloride, a first halide, LiF, and Li2O, and refine them by ball milling to obtain a first mixed powder; Add lithium chloride, a second halide, and ammonium chloride to deionized water, stir, and then dry the solution to a powder state; In a saturated solution of LiCl, add an electrolyte, then add polydopamine, stir, and concentrate to control the viscosity at a set value to obtain a mixed slurry; After reacting the first mixed powder with the mixed slurry and drying, the obtained LTXC-PDA@LZCFO is mixed with a binder and a pore former, added with a solvent to form a slurry, dispersed and evaporated to obtain an electrolyte slurry, and the electrolyte slurry is coated on both sides of a polyimide-based membrane and dried to obtain an electrolyte membrane; The electrolyte membrane is subjected to atomic deposition, and a metal layer is plated on one side to obtain a solid electrolyte membrane.

Description

Technical Field

[0001] This application belongs to the technical field of energy materials, and particularly relates to a preparation method and application of a solid electrolyte membrane. Background Art

[0002] At present, the development of batteries faces two major challenges: how to improve the energy density of batteries and how to improve the safety of batteries. At present, the energy density of power batteries has reached 300 Wh / kg. In order to increase the single-charge driving range of electric vehicles, it is necessary to further improve the energy density. Replacing the current graphite anode with a lithium alloy anode can greatly improve the energy density of the battery. However, the lithium alloy will continuously react with the currently used liquid electrolyte. Due to its non-diffusibility, the solid electrolyte system is theoretically more likely to form a stable interface, thus being compatible with the lithium alloy anode. At the same time, solid electrolytes are not flammable. Replacing the flammable organic liquid electrolyte based on carbonates will significantly improve the safety of the battery.

[0003] Solid electrolytes are the core components of solid-state batteries, and determine the overall performance of the battery through their ion transport ability and mechanical stability. Among various solid electrolytes, inorganic solid electrolytes have the characteristics of high ionic conductivity and high mechanical strength. However, their brittleness and complex preparation processes may limit the flexibility of the battery and increase the production cost of the battery. In contrast, solid polymer electrolytes show great advantages in commercial applications, such as low cost, excellent flexibility, and good interfacial contact. However, challenges such as relatively low ionic conductivity and poor mechanical properties still exist for solid polymer electrolytes. Current halide electrolytes and halides are relatively sensitive to water and oxygen in the air, which makes it necessary to operate in a glove box environment, hindering large-scale production. The lithium metal anode in lithium metal batteries with halide electrolytes is very unstable, including poor chemical stability and electrochemical stability. When using lithium metal as the anode in current halide all-solid-state batteries, the uniformity of the lithium ion product is very poor, resulting in very serious lithium dendrite growth, and ultimately easily leading to severe battery life attenuation and short circuit. The high reactivity of halide electrolytes with the anode results in halides not being able to be used as a good solid electrolyte layer. Therefore, designing solid electrolytes with high electrochemical and mechanical properties is crucial for promoting battery technology. Summary of the Invention

[0004] This application provides a preparation method and application of a solid electrolyte membrane, aiming to solve the problems of relatively low ionic conductivity and poor mechanical properties in solid polymer electrolytes to a certain extent.

[0005] In a first aspect, this application provides a preparation method of a solid electrolyte membrane, including the following steps:

[0006] S1. Mix lithium chloride, the first halide, LiF, and Li2O, and refine them by ball milling to obtain the first mixed powder;

[0007] S2. Add lithium chloride, the second halide, and ammonium chloride to deionized water. After stirring, dry the solution to a powder state to obtain the electrolyte. The second halide is a combination of one or more of YCl3, ScCl3, ErCl3, InCl3 and TaCl4;

[0008] S3. In a saturated solution of lithium chloride, add the electrolyte obtained in S2, and then add polydopamine. After stirring, concentrate to control the viscosity at a set value to obtain a mixed slurry;

[0009] S4. Mix the first mixed powder obtained in S1 with the mixed slurry obtained in S3, and react at a set pressure and set temperature to obtain an intermediate product;

[0010] S5. Dry the intermediate product to obtain Li 2+b Ta a X b Cl6 - polydopamine-coated LZCFO electrolyte, denoted as LTXC-PDA@LZCFO;

[0011] S6. Mix the LTXC-PDA@LZCFO with a binder and a pore former, add a solvent to prepare a slurry, disperse it and evaporate to obtain an electrolyte slurry. Coat the electrolyte slurry on both sides of a polyimide base film and dry it to obtain an electrolyte membrane;

[0012] S7. Perform atomic deposition on the electrolyte membrane to form a metal layer on one side to obtain the solid electrolyte membrane.

[0013] In some embodiments, in step S1, the first halide is ZrCl4; the molar ratio of lithium chloride, the first halide, LiF, and Li2O is d∶e∶f∶g, where 0 < d ≤ 4, 0 < e ≤ 1, 0 ≤ f ≤ 2, 0 ≤ g ≤ 0.5; the particle size of the refined first mixed powder is 1 μm - 2 μm.

[0014] In some embodiments, in step S2, the molar ratio of lithium chloride, the second halide, and ammonium chloride is x∶y∶z, where 0 < x ≤ 3, 0 < y ≤ 1.5, 0 < z ≤ 3; the drying is to dry the solution to a powder state at 200 - 800 °C. S1 obtains LZCFO (Li 2.5 ZrCl5F 0.5 O 0.5 ), and S2 obtains Li 2+b Ta a X b Cl6.

[0015] In some embodiments, the electrolyte in step S3 is Li 2+b Ta a X b Cl6, where X is a composition of 0, 1, or 2 or more of Y, Sc, Er, and In, 0.1 ≤ a ≤ 3, 0 ≤ b ≤ 5; the molar ratio of the electrolyte to polydopamine is 1∶(0.01 - 0.5), the stirring is carried out at 5 - 200 °C, and the set value of the viscosity after concentration is 10 - 5000 cps.

[0016] In some embodiments, the set temperature in step S4 is -20 °C to 150 °C, the set pressure is 1 - 5 standard atmospheres, and the reaction is carried out in an atmosphere of saturated ammonia.

[0017] In some embodiments, the drying conditions in step S5 are: in a spray dryer under a nitrogen atmosphere, the drying temperature is 60 - 300 °C.

[0018] In some embodiments, the binder in step S6 is a PMMA - type binder, the pore - forming agent is starch, the mass ratio of the electrolyte powder∶binder∶starch is 100∶(1 - 5)∶(1 - 15), and the solvent is a deionized aqueous solution containing 15% NH4Cl.

[0019] In some embodiments, the dispersion in step S6 is that the slurry is dispersed from fast to slow at a rate of 150 - 3000 r / min for 2 h - 50 h; the evaporation is carried out at 60 - 120 °C in a rotary evaporator to increase the solid content of the slurry to 45% - 55%, and at the same time the pH is reduced to 7 ± 1; the thickness of the polyimide - based film is 3 - 14 μm, the porosity is ≥50%, and the thickness of the coating is 1 μm - 5 μm.

[0020] In some embodiments, the metal layer in step S7 is a combination of one or more of metallic tungsten, tungsten oxide, and tungsten carbide.

[0021] In a second aspect, the present invention also provides an application of a solid - state electrolyte membrane obtained by the preparation method of the solid - state electrolyte membrane according to any one of the first aspects in a battery.

[0022] It can be understood that the beneficial effects of the above - mentioned second aspect can be referred to the relevant descriptions in the above - mentioned first aspect content, and will not be elaborated here.

[0023] Compared with the prior art, the beneficial effects of the present application are:

[0024] In S1, argon gas with oxygen is used for ball milling to prepare the electrolyte, aiming to form a composite shell layer of ZrO2 and Li2O on the surface of the electrolyte particles, which can increase the mechanical strength of the electrolyte, prevent the direct contact between the electrolyte particles and the outside world, effectively reduce side reactions, and enhance the stability of the halide electrolyte in air. The halide electrolyte will not directly contact with the water and oxygen in the air, resulting in changes in the structure and crystal phase of the halide.

[0025] In S3, polydopamine is introduced with Li 2+b Ta a X b Cl6 halide electrolyte to form a polydopamine-halide electrolyte composite coating phase. Polydopamine and Li 2+b Ta a X b Cl6 halide has very good stability and adhesion ability, can form strong chemical bonds, and can inhibit the reduction of Li 2+b Ta a X b Cl6 halide, which cannot be replaced by other substances. At the same time, polydopamine can tightly coat the Li 2+b Ta a X b Cl6 halide electrolyte on the electrolyte particles obtained in S2. And polydopamine has strong negative electricity, with a wide conjugate region and high π electron density, which can guide the smooth deposition of lithium ions on the negative electrode surface and reduce the generation of lithium dendrites.

[0026] In S5, spray drying technology is used for drying, which can obtain a better coating layer. At the same time, using Li 2+b TaX b Cl6 to coat LZCFO with an oxide layer can form a screw effect, that is, unstable dead lithium will react with Li 2+b TaX b Cl6 and be consumed, thereby protecting the inner layer of LZCFO to efficiently transport lithium ions, increasing the service life of the lithium metal battery and reducing side reactions at the negative electrode.

[0027] In S6, starch is used as an additive. The glutamine amino acid in the amyloid fibers of starch has a high adsorption energy for Li, so a stable solid electrolyte interface film rich in Li ions is formed on the anode during the cycling process, which can homogenize the electric field and Li ion concentration and fundamentally inhibit the formation of dendrites.

[0028] In S7, tungsten metal is deposited on the coating by an ALD atomic deposition instrument, which can be deposited on Li 2+b Ta a X bAfter Cl6 reacts with dead lithium to form XCl3, tungsten reacts with XCl3 to form an X-W alloy, preventing side reaction products from hindering lithium ion transport.

[0029] Generally speaking, this solution increases the mechanical strength of the electrolyte, prevents direct contact between electrolyte particles and the outside world, effectively reduces side reactions, and at the same time enhances the stability of the halide electrolyte in air; it improves the ability of lithium ions to deposit uniformly, and lithium ions deposit smoothly on the surface of the negative electrode, reducing the generation of lithium dendrites. At the interface, the electric field and Li ion concentration can be homogenized, fundamentally inhibiting the formation of dendrites and increasing the battery cycle life. Brief Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0031] Figure 1 It is the LTC-PDA@LZCFO electrolyte obtained in step S5 of Embodiment 1 of the present invention, where (a) is a schematic structural diagram; (b) is a TEM image;

[0032] Figure 2 It is a schematic diagram of the process of the starch@LTC-PDA@LZCFO electrolyte membrane obtained in step S6 of Embodiment 1 of the present invention;

[0033] Figure 3 It is a diagram of the electrolyte membrane obtained in Embodiment 1 of the present invention, where (a) is a schematic structural diagram of the electrolyte membrane; (b) is a SEM cross-sectional view of the electrolyte membrane after coating in step S6; (c) is an interfacial phase diagram of the all-solid-state battery composed of the electrolyte membrane after cycling;

[0034] Figure 4 It is the EIS impedance comparison between some embodiments and comparative examples;

[0035] Figure 5 It is a cycle data diagram of the NCM83 / / SE / / Li battery made of the electrolyte membranes of Embodiment 3 and Comparative Example 7. Detailed Description of the Specific Embodiments

[0036] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clear, the following further details the present application in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0037] In this application, the term "and / or" describes the relationship between related objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, or B exists alone. Here, A and B can be singular or plural. The character " / " generally indicates that the related objects before and after are in an "or" relationship.

[0038] In this application, "at least one" means one or more, and "a plurality" means two or more. "At least one of the following items" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can both represent: a, b, c, a~b (i.e., a and b), a~c, b~c, or a~b~c, where a, b, and c can be single or multiple respectively.

[0039] The terms "first" and "second" are only used for descriptive purposes to distinguish objects such as substances from each other, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. For example, without departing from the scope of the embodiments of this application, the first XX can also be referred to as the second XX, and similarly, the second XX can also be referred to as the first XX. Thus, the features defined with "first" and "second" can explicitly or implicitly include one or more of such features.

[0040] The terms used in the embodiments of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms "a", "the", and "said" used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0041] It should be understood that in various embodiments of this application, the magnitude of the sequence numbers of the processes does not mean the order of execution. Some or all of the steps can be executed in parallel or successively. The execution order of each process should be determined by its function and internal logic and should not constitute any limitation to the implementation process of the embodiments of this application.

[0042] The weights of the related components mentioned in the specification of the embodiments of this application not only can refer to the specific contents of each component, but also can represent the proportional relationship of the weights between the components. Therefore, as long as the contents of the related components in the specification of the embodiments of this application are scaled up or down in proportion, they are within the scope disclosed in the specification of the embodiments of this application. Specifically, the mass described in the specification of the embodiments of this application can be mass units well-known in the chemical field such as μg, mg, g, kg, etc.

[0043] Unless otherwise defined, all technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0044] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in this application can be obtained through market purchases or can be prepared by existing methods.

[0045] The technical solutions of this application will be described below through specific examples and comparative examples.

[0046] To enable those skilled in the art to clearly understand the above implementation details and operations of this application, and to significantly demonstrate the advanced performance of the embodiments of this application, the above technical solutions will be illustrated by multiple examples below.

[0047] Example 1:

[0048] A preparation method and application of a solid electrolyte membrane:

[0049] S1: Charge LiCl, ZrCl4, LiF, and Li2O in a molar ratio of 1:1:0.5:0.5. Place the materials in a mixing machine and mix for 60 min while maintaining an argon atmosphere with oxygen. Then, put the mixed materials into a ball mill. The ball-to-material ratio is 40:3, and the diameters of the balls are selected as 10 mm:5 mm:3 mm = 4:1:5. Introduce a mixture of oxygen and argon into the ball mill tank. The atmosphere mixture includes 95% by volume of argon and 5% by volume of oxygen. Perform high-energy ball milling at a rotation speed of 750 r / min for 300 min, and open the ball mill tank every 30 min for gas renewal. Finally, take out the powder in the ball mill tank for refinement to obtain a powder with a particle size of 1 μm.

[0050] S2: Add LiCl, TaCl4, and NH4Cl to deionized water in a molar ratio of 2:1:3, stir at a stirring rate of 100 r / min for 30 min, and then dry the solution to a powder state at 200 °C.

[0051] S3: Add Li2TaCl6 to a saturated solution of LiCl, then add a certain amount of polydopamine. The molar ratio of the electrolyte to polydopamine is controlled at 1:0.05. Stir well at 45 °C and continuously concentrate the solution to control the viscosity at 200 ± 20 cps.

[0052] S4: Mix the powder obtained in S1 and the slurry obtained in S3 together. In a closed high-pressure reactor, set the temperature of the reactor to be kept at -10 °C, 0 °C, and 10 °C for 30 min respectively in sequence. The atmosphere in the high-pressure reactor is saturated ammonia gas and 5 atmospheres.

[0053] S5: Take out the reaction product of step S4 for spray drying. The inside of the spray dryer requires a nitrogen atmosphere and the oxygen content is less than 0.01 ppm, and the drying temperature is 95 °C to obtain the Li2TaCl6-polydopamine-coated LZCFO electrolyte, denoted as LTC-PDA@LZCFO. LTC-PDA@LZCFO is as Figure 1 shown.

[0054] S6: Mix the LTC-PDA@LZCFO powder with the binder GR-508 and starch. The mass ratio of the electrolyte powder: binder: starch is 100∶3∶5. Use a deionized aqueous solution containing 15% NH4Cl as the solvent to prepare a slurry with a solid content of 25%. Disperse the slurry at the rates of 2000 r / min, 1000 r / min, and 500 r / min from fast to slow for 6 h. After dispersion, transfer it to a rotary evaporator for evaporation at 60 °C to increase the solid content of the slurry to 50% and simultaneously reduce the pH to 7 ± 1. Then take out the slurry and use a coater to coat the slurry on a polyimide base film with a thickness of 14 μm, and the coating thickness is 2 μm. Coat both sides of the base film. After coating, conduct continuous vacuum drying at a temperature of 200 °C for 8 h. The starch@LTC-PDA@LZCFO electrolyte membrane is as Figure 2 shown.

[0055] S7: Put the electrolyte membrane obtained in S6 into an ALD atomic deposition device and deposit a layer of metallic tungsten with a thickness of 3 nm on one side. The side coated with tungsten is used as the negative electrode side of the electrolyte layer to obtain the electrolyte membrane of this solution. The obtained product is as Figure 3 shown, where (a) is the conceptual structure diagram of the electrolyte membrane; (b) is the SEM cross-sectional diagram of the electrolyte membrane after coating in step S6; (c) is the interfacial phase diagram after the product composes a all-solid-state battery is cycled.

[0056] Example 2:

[0057] S1: LiCl, ZrCl4, LiF and Li2O are mixed in a molar ratio of 2:1:0:0, and the materials are mixed in a mixing machine for 30 minutes, maintaining an argon atmosphere with oxygen; then the mixed materials are put into a ball mill, the ball-to-material ratio is 40:5, the ball diameter is selected to be 10mm:5mm:3mm=3:1:1, and an atmosphere mixture of oxygen and argon is introduced into the ball mill, the atmosphere mixture includes 99% volume of argon and 1% volume of oxygen, and high-energy ball milling is performed, the speed is set at 500r / min, the ball milling time is 15min, and the ball mill is opened every 30min for gas renewal, and finally the powder in the ball mill is taken out for refinement to obtain LZC powder with a particle size of 2μm.

[0058] S2: LiCl, TaCl4, ScCl3, and NH4Cl were added to deionized water at a molar ratio of 2.3:0.7:0.3:3, stirred at a stirring rate of 300 r / min for 30 min, and then dried at 200 °C to a powder state to obtain Li 2.3 Ta 0.7 Sc 0.3 Cl6 electrolyte.

[0059] S3: Add Li to the LiCl saturated solution 2.3 Ta 0.7 Sc 0.3 Cl6 electrolyte, and then add a certain amount of polydopamine, the molar ratio of electrolyte to polydopamine is controlled at 1:0.1, fully stirred at 50°C, and the solution is continuously concentrated to control the viscosity to 300±20 cps.

[0060] S4: The powder obtained in S1 and the slurry obtained in S3 are mixed together, and the temperature of the reactor is set to -20°C, 0°C, 20°C, 40°C, and 60°C in a closed autoclave for 15 minutes respectively. The atmosphere in the autoclave is saturated ammonia and 5 atmospheres.

[0061] S5: Take out the reaction product of step S4 and spray dry it. The spray dryer requires a nitrogen atmosphere and an oxygen content of less than 0.01 ppm. The drying temperature is 100°C to obtain Li 2.3 Ta 0.7 Sc 0.3 Cl6-polydopamine coated LZCFO electrolyte, denoted as LTSC-PDA@LZCFO.

[0062] S6: Mix LTSC-PDA@LZCFO powder with a binder and a pore-forming agent. The binder is GR-508 produced by Gaorui Power Source, and the pore-forming agent is starch. The mass ratio of electrolyte powder: binder: starch is 100:3:15. The solvent is a deionized water solution containing 15% NH4Cl. A slurry with a solid content of 15%-30% is prepared. The slurry is dispersed from fast to slow at a rate of 150-3000r / min for 6h, and then transferred to a rotary evaporator for evaporation at 60°C to increase the solid content of the slurry to 50%. At the same time, the pH is reduced to 7±1. The slurry is then taken out and coated on a polyimide base film with a thickness of 7μm using a coater. The coating thickness is 3μm, and both sides of the base film are coated. After coating, it is continuously dried at a temperature of 200°C under negative pressure for 8h.

[0063] S7: Place the electrolyte membrane obtained in S6 into an ALD atomic deposition device, and coat a layer of metal element tungsten with a thickness of 1 nm on one side. The side coated with tungsten is used as the negative electrode side of the electrolyte layer to obtain the electrolyte membrane of this scheme.

[0064] Embodiment 3:

[0065] S1: LiCl, ZrCl4, LiF and Li2O are mixed in a molar ratio of 1.5:1:0.5:0, and the materials are mixed in a mixing machine for 15 minutes, maintaining an argon atmosphere; then the mixed materials are put into a ball mill, the ball-to-material ratio is 40:4, the ball diameter is selected to be 10mm:5mm:3mm=2:2:3, argon is introduced into the ball mill, high-energy ball milling is performed, the speed is set at 600r / min, the ball mill time is 360min, and the ball mill is opened every 30min for gas renewal, and finally the powder in the ball mill is taken out for refinement to obtain a powder with a particle size of 1.2μm.

[0066] S2: LiCl, TaCl4, ScCl3, ErCl3, and NH4Cl were added to deionized water at a molar ratio of 3:0.33:0.33:0.33:3, stirred at a stirring rate of 150 r / min for 60 min, and then dried at 200 °C to a powder state to obtain Li 2.99 Ta 0.33 Sc 0.33 Er 0.33 Cl6 electrolyte.

[0067] S3: Add LiCl to the saturated solution to obtain Li 2.99 Ta 0.33 Sc 0.33 Er 0.33Cl6 electrolyte, and then a certain amount of polydopamine is added. The molar ratio of the electrolyte to polydopamine is controlled at 1:0.5. Stir well at 50 °C and continuously concentrate the solution to control the viscosity at 500 ± 20 cps.

[0068] S4: Mix the powder obtained in S1 and the slurry obtained in S3 together. In a closed high-pressure reactor, the temperature of the reactor is set to be kept at 20 °C, 40 °C, 60 °C, 80 °C, 100 °C, and 120 °C for 10 min respectively. The atmosphere in the high-pressure reactor is saturated ammonia gas and 5 atmospheres.

[0069] S5: Take out the reaction product of S4 for spray drying. The spray dryer requires a nitrogen atmosphere and the oxygen content is less than 0.01 ppm. The drying temperature is 90 °C to obtain Li 2.99 Ta 0.33 Sc 0.33 Er 0.33 Cl6-polydopamine-coated LZCFO electrolyte, denoted as LTSEC-PDA@LZCFO.

[0070] S6: Mix the LTSEC-PDA@LZCFO powder with the binder Gr-506 and starch. The mass ratio of the electrolyte powder: binder: starch is 100:5:1. The solvent used is deionized aqueous solution containing 15% NH4Cl to prepare a slurry with a solid content of 20%. The slurry is dispersed at a rate of 3000 r / min for 6 h. After dispersion, it is transferred to a rotary evaporator for evaporation at 60 °C to increase the solid content of the slurry to 50%, and at the same time the pH is reduced to 7 ± 1. Then the slurry is taken out and coated on a 10-μm-thick polyimide base film using a coater. The coating thickness is 2 μm, and both sides of the base film are coated. After coating, it is dried under negative pressure with continuous air extraction at 200 °C for 8 h.

[0071] S7: Put the electrolyte membrane obtained in S6 into an ALD atomic deposition device and deposit a 5-nm-thick metal tungsten on one side. The side coated with tungsten is used as the negative electrode side of the electrolyte layer to obtain the electrolyte membrane of this scheme.

[0072] Comparative Example 1: Compared with Example 1, there is no S3. The powder obtained in S2 is directly mixed with the powder obtained in S1 and then enters S4.

[0073] Comparative Example 2: Compared with Example 1, there is no pore-forming agent starch in S6. The binder and deionized aqueous solution containing 15% NH4Cl are directly used to prepare a slurry.

[0074] Comparative Example 3: Compared with Example 1, there is no binder in S6. The starch and deionized aqueous solution containing 15% NH4Cl are directly used to prepare a slurry.

[0075] Comparative Example 4: Compared with Example 2, in S4, it was kept warm at -20 °C for 75 min, and the others remained unchanged.

[0076] Comparative Example 5: Compared with Example 2, in S5, freeze drying was used instead of spray drying.

[0077] Comparative Example 6: Compared with Example 2, in S6, instead of using a rotary evaporator for evaporation, an ordinary evaporating dish was used for evaporation in a vacuum drying oven.

[0078] Comparative Example 7: Compared with Example 3, S7 was cancelled.

[0079] Comparative Example 8: Compared with Example 3, the deionized water with 15% NH4Cl used in all steps was replaced with pure deionized water.

[0080] Comparative Example 9: Compared with Example 3, the saturated LiCl solution in S3 was replaced with pure deionized water.

[0081] Comparative Example 10: Compared with Example 3, S2, S3, and S4 were cancelled.

[0082] Comparative Example 11: Compared with Example 1, TaCl4 was not used in S2.

[0083] Comparative Example 12: Compared with Example 2, TaCl4 was not used in S2.

[0084] Comparative Example 13: Compared with Example 3, TaCl4 was not used in S2.

[0085] Test Example:

[0086] I. EIS impedance comparison. The results are as Figure 4 shown. Compared with Comparative Examples 1 to 4, the EIS impedance of the electrolyte membranes of Example 1 and Example 2 is only 25% of that of the comparative examples, indicating that the present solution significantly improves the lithium ion conductivity.

[0087] II. Cycling test: The electrolyte powder obtained in step S5 of Example 3 and Comparative Example 7 and the positive electrode active material NCM83 were mixed in a mass ratio of 3:7, and in addition, 0.05 mass ratio of VGCF was added, and ground for 15 min to obtain a positive electrode powder. 20 mg of the positive electrode mixed powder was used, and the electrolyte membranes of Example 3 and Comparative Example 7 were respectively used, and the negative electrode used a lithium metal sheet with a thickness of 20 μm, and all-solid-state batteries were respectively assembled for testing, and the results are as Figure 5 shown. Compared with Comparative Example 7, Example 3 has a very large advantage in cycling performance, and still retains 100% of the capacity retention rate after 50 cycles, while Comparative Example 7 only has a capacity retention rate of nearly 95%.

[0088] III. Performance Test: The electrolyte powders obtained in Step S5 of Examples 1 to 3 and Comparative Examples 1 to 13 were respectively mixed with the positive electrode active material NCM83 in a mass ratio of 3:7. In addition, 0.05 mass ratio of VGCF was added, and the mixture was ground for 15 min to obtain the positive electrode powder. 20 mg of the positive electrode mixed powder was used, and the electrolyte membranes of each example and each comparative example were respectively adopted. The negative electrode used a lithium metal sheet with a thickness of 20 μm, and all-solid-state batteries were assembled respectively for testing to obtain the results in Table 1:

[0089]

[0090] As can be seen from the above table, compared with the comparative examples, all three examples showed better Coulombic efficiency and capacity retention rate, indicating that this solution has a very obvious improvement in improving ionic conductivity, interface stability and reducing side reactions. In the above examples, the descriptions of each example have their own emphases. For parts not detailed or recorded in a certain example, reference can be made to the relevant descriptions of other examples.

[0091] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of each embodiment of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for preparing a solid electrolyte membrane, characterized in that, It includes the following steps: S1. Mix lithium chloride, the first halide, LiF, and Li2O, and perform ball milling and refinement under an argon atmosphere with oxygen to obtain a first mixed powder. The first halide is ZrCl4; S2. Add lithium chloride, the second halide, and ammonium chloride to deionized water. After stirring, dry the solution to a powder state to obtain an electrolyte. The second halide is a combination of one or more of YCl3, ScCl3, ErCl3, InCl3 and a composition of TaCl4; S3. Add the electrolyte obtained in S2 to a saturated solution of lithium chloride, then add polydopamine. After stirring, concentrate to control the viscosity at a set value to obtain a mixed slurry; S4. Mix the first mixed powder obtained in S1 with the mixed slurry obtained in S3, and react under a set pressure and set temperature to obtain an intermediate product; S5. Dry the intermediate product using spray drying technology to obtain Li 2+b Ta a X b Cl6-polydopamine-coated LZCFO electrolyte, denoted as LTXC-PDA@LZCFO; S6. Mix the LTXC-PDA@LZCFO with a binder and a pore former, add a solvent to configure it into a slurry, disperse it and then evaporate to obtain an electrolyte slurry. Coat the electrolyte slurry on both sides of a polyimide-based film and dry it to obtain an electrolyte membrane; S7. Perform atomic deposition on the electrolyte membrane to form a tungsten layer on one side to obtain the solid electrolyte membrane; In step S4, the set temperature is -10°C to 150°C, the set pressure is 1 - 5 standard atmospheres, and the reaction is carried out in an atmosphere of saturated ammonia; In step S6, the evaporation is carried out at 60 - 120°C in a rotary evaporator; 2. The preparation method according to claim 1, characterized in that, In step S1, the molar ratio of lithium chloride, the first halide, LiF, and Li2O is d∶e∶f∶g, where 0 < d ≤ 4, 0 < e ≤ 1, 0 ≤ f ≤ 2, 0 ≤ g ≤ 0.5; the particle size of the refined first mixed powder is 1μm - 2μm; 3. The preparation method according to claim 1, characterized in that, In step S2, the molar ratio of lithium chloride, the second halide, and ammonium chloride is x∶y∶z, where 0 < x ≤ 3, 0 < y ≤ 1.5, 0 < z ≤ 3; the drying is to dry the solution to a powder state at 200 - 800°C; 4. The preparation method according to claim 1, characterized in that, The electrolyte described in step S3 is Li 2+b Ta a X b Cl6, where X is one or a combination of two or more of Y, Sc, Er, and In, 0.1 ≤ a ≤ 3, 0 ≤ b ≤ 5; the molar ratio of the electrolyte to polydopamine is 1:(0.01 - 0.5), the stirring is carried out under the condition of 5 - 200 °C, and the set value of the viscosity after concentration is 10 - 5000 cps.

5. The preparation method according to claim 1, characterized in that, The drying conditions in step S5 are: in a spray dryer under a nitrogen atmosphere, the drying temperature is 60 - 300°C; 6. The preparation method according to claim 1, characterized in that, In step S6, the binder is a PMMA-based binder, the pore former is starch, and the mass ratio of LTXC-PDA@LZCFO powder∶binder∶starch is 100∶(1 - 5)∶(1 - 15), and the solvent is a deionized aqueous solution containing 15% NH4Cl; 7. The preparation method according to claim 1, characterized in that, In step S6, the dispersion is that the slurry is dispersed from fast to slow at a rate of 150 - 3000 r / min for 2h - 50h; the evaporation is to increase the solid content of the slurry to 45% - 55% while reducing the pH to 7 ± 1; the thickness of the polyimide-based film is 3 - 14μm, the porosity is ≥50%, and the coating thickness is 1μm - 5μm; 8. Application of a solid electrolyte membrane obtained by the preparation method of the solid electrolyte membrane according to any one of claims 1 to 7 in a battery.

Images