Asymmetric solid-state electrolyte membrane, preparation method therefor, and use thereof in battery

Abstract

Provided in the present invention are an asymmetric solid-state electrolyte membrane, a preparation method therefor, and a use thereof in a battery. The asymmetric solid-state electrolyte membrane comprises: a base membrane, a first coating layer, and a second coating layer, wherein the base membrane has a first surface and a second surface, the second surface is opposite to the first surface, the first coating layer is formed on the first surface of the base membrane and comprises lithium titanium aluminium phosphate, and the second coating layer is formed on the second surface of the base membrane and comprises a solid-state electrolyte material other than lithium titanium aluminium phosphate. By selecting a solid-state electrolyte that is stable at the negative electrode for coating, the problem of LATP degrading the performance of the negative electrode is solved, improving the overall performance of the membrane, and the coating process is compatible with existing production lines without the need for great modification.

Description

Asymmetric solid electrolyte membranes, their preparation methods, and their applications in batteries Technical Field

[0001] This invention relates to the field of battery separator technology, and particularly to an asymmetric solid electrolyte membrane, its preparation method, and its application in batteries. Background Technology

[0002] Lithium-ion batteries are a type of efficient and clean energy storage device that has been widely used in portable electronic devices, electric vehicles, and large-scale energy storage systems since their commercialization. Their working principle primarily relies on the reversible migration of lithium ions between the positive and negative electrodes, enabling the conversion between chemical energy and electrical energy. However, with the continuous expansion of application areas and the increasing market demand, higher requirements are being placed on lithium batteries in terms of energy density, safety, and cycle life.

[0003] Currently, alumina separators are used in traditional commercial lithium-ion batteries, but their performance is limited. Solid-state electrolytes (SSEs) have attracted significant research attention in recent years due to their advantages such as high ionic conductivity, excellent safety, and good stability. LATP (Lithium Acid Electrolyte) is currently the most mature, stable to water and air, and relatively inexpensive, making it the fastest-growing coating for separators, with overall performance superior to alumina separators. However, the reaction of LATP with Li can cause performance degradation in some cell systems due to high-temperature storage and cycling. Therefore, there is an urgent need to develop novel coating structures to address the performance degradation of LATP coatings when facing the negative electrode, thereby improving the overall performance of the separator. Summary of the Invention

[0004] In this invention, an asymmetric solid electrolyte coating structure is developed. The coating facing the positive electrode uses LATP (lithium aluminum titanium phosphate), while the coating facing the negative electrode uses other types of solid electrolytes. This novel coating structure solves the problem of performance degradation facing the negative electrode, improves the overall performance of the solid electrolyte membrane, and provides new ideas for the development of subsequent related products.

[0005] The first aspect of the invention is implemented as follows:

[0006] An asymmetric solid electrolyte membrane includes: a base membrane, a first coating, and a second coating. The base membrane has a first surface and a second surface, the second surface being opposite to the first surface. The first coating is formed on the first surface of the base membrane and contains lithium titanium aluminum phosphate. The second coating is formed on the second surface of the base membrane and contains a solid electrolyte material other than lithium titanium aluminum phosphate.

[0007] In an embodiment of the present invention, the solid electrolyte material includes one or more of LLZO (lithium lanthanum zirconium oxide), LLZTO (lithium lanthanum zirconium tantalum oxide), LLTO (lithium lanthanum titanium oxide), LAGP (lithium aluminum germanium phosphate), Li2ZrF6, Li2ZrCl6, and Li2AlF6.

[0008] In an embodiment of the present invention, the thickness of the base film is 5 μm to 16 μm, the thickness of the first coating is 2 μm to 4 μm, and the thickness of the second coating is 2 μm to 4 μm.

[0009] In an embodiment of the present invention, the base film is one or more of polyethylene base film and polypropylene base film.

[0010] In an embodiment of the present invention, the particle size D50 of the lithium titanium aluminum phosphate particles in the first coating is 0.1 μm to 3 μm, and the particle size D50 of the solid electrolyte material particles in the second coating is 0.1 μm to 3 μm.

[0011] The second aspect of the invention is implemented as follows:

[0012] A battery includes: a positive electrode, a negative electrode, and a separator, the separator being disposed between the positive electrode and the negative electrode and including an asymmetric solid electrolyte membrane as described above, the first coating facing the positive electrode and the second coating facing the negative electrode.

[0013] The third aspect of the invention is implemented as follows:

[0014] A method for preparing an asymmetric solid electrolyte membrane includes: coating a first slurry and a second slurry onto a first surface and a second surface opposite to the first surface of a base membrane, wherein the first slurry comprises lithium titanium aluminum phosphate and the second slurry comprises a solid electrolyte material other than lithium titanium aluminum phosphate; and drying to obtain the asymmetric solid electrolyte membrane.

[0015] In an embodiment of the present invention, the solid electrolyte material includes one or more of LLZO (lithium lanthanum zirconium oxide), LLZTO (lithium lanthanum zirconium tantalum oxide), LLTO (lithium lanthanum titanium oxide), LAGP (lithium aluminum germanium phosphate), Li2ZrF6, Li2ZrCl6, and Li2AlF6.

[0016] In an embodiment of the present invention, the first slurry further includes one or more of a dispersing agent, a binder, and a wetting agent, and the second slurry further includes one or more of a dispersing agent, a binder, and a wetting agent.

[0017] In an embodiment of the present invention, the dispersing agent of the first slurry includes one or more of sodium polyacrylate, polyethylene oxide, polyvinyl alcohol, methylcellulose, hydroxyethylcellulose, sodium carboxymethylcellulose, polyether silicone copolymer, polyoxyethylene alkanolamide, and ammonium polyacrylate; the binder of the first slurry includes one or more of acrylate, methacrylate, a polymer obtained by copolymerizing styrene-butadiene rubber with olefins, a polymer obtained by copolymerizing styrene-butadiene rubber with esters, a polymer obtained by copolymerizing nitrile rubber with olefins, and a polymer obtained by copolymerizing nitrile rubber with esters; and the wetting agent of the first slurry includes one or more of polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether, and polyoxyethylene polyoxypropylene block copolymer.

[0018] In an embodiment of the present invention, the dispersing agent of the second slurry includes one or more of sodium polyacrylate, polyethylene oxide, polyvinyl alcohol, methylcellulose, hydroxyethylcellulose, sodium carboxymethylcellulose, polyether silicone copolymer, polyoxyethylene alkanolamide, and ammonium polyacrylate; the binder of the second slurry includes one or more of acrylate, methacrylate, a polymer obtained by copolymerizing styrene-butadiene rubber with olefins, a polymer obtained by copolymerizing styrene-butadiene rubber with esters, a polymer obtained by copolymerizing nitrile rubber with olefins, and a polymer obtained by copolymerizing nitrile rubber with esters; and the wetting agent of the second slurry includes one or more of polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether, and polyoxyethylene polyoxypropylene block copolymer.

[0019] In an embodiment of the present invention, the first slurry is an aqueous slurry with a solid content of 40% to 50%, a viscosity of 10 mPa·s to 50 mPa·s, and a pH of 7 to 10; the second slurry is an aqueous slurry with a solid content of 40% to 50%, a viscosity of 10 mPa·s to 50 mPa·s, and a pH of 7 to 10.

[0020] The beneficial effects of this invention are as follows:

[0021] By selecting a solid electrolyte that is stable to the negative electrode for coating, the problem of LATP degrading the performance of the negative electrode is solved, and the overall performance of the membrane is improved. The coating process is compatible with existing production lines and does not require major modifications. Attached Figure Description

[0022] Figure 1 illustrates the asymmetric solid electrolyte membrane of the present invention. Detailed Implementation

[0023] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0025] Please refer to Figure 1, which is the asymmetric solid electrolyte membrane of the present invention, which includes at least the following structure: a base membrane (1), a first coating (21), and a second coating (22). The base membrane (1) has a first surface and a second surface, with the second surface opposite to the first surface. The first coating (21) is formed on the first surface of the base membrane (1) and contains lithium titanium aluminum phosphate, and the second coating (22) is formed on the second surface of the base membrane (1) and contains solid electrolyte materials other than lithium titanium aluminum phosphate.

[0026] The base film (1) can be one or more of polyethylene base film and polypropylene base film. In addition, the thickness of the base film (1) can be from 5 μm to 16 μm, preferably any value or a range between any two values ​​of 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, and 16 μm.

[0027] The thickness of the first coating (21) can be from 2 μm to 4 μm, preferably any value or a range between any two of 2 μm, 2.5 μm, 3 μm, 3.5 μm, and 4 μm. In addition to containing lithium aluminum titanium phosphate, the first coating (21) may also include one or more of a dispersant, a binder, and a wetting agent. The dispersant may include one or more of sodium polyacrylate, polyethylene oxide, polyvinyl alcohol, methylcellulose, hydroxyethylcellulose, sodium carboxymethylcellulose, polyether silicone copolymer, polyoxyethylene alkanolamide, and ammonium polyacrylate. The binder may include one or more of acrylates, methacrylates, polymers obtained by copolymerizing styrene-butadiene rubber with olefins, polymers obtained by copolymerizing styrene-butadiene rubber with esters, polymers obtained by copolymerizing nitrile rubber with olefins, and polymers obtained by copolymerizing nitrile rubber with esters. The wetting agent may include one or more of polyoxyethylene alkylphenol ethers, polyoxyethylene fatty alcohol ethers, and polyoxyethylene polyoxypropylene block copolymers. In addition, the particle size D50 of lithium titanium aluminum phosphate can be from 0.1 μm to 3 μm, preferably any value or a range between any two values ​​of 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm.

[0028] The thickness of the second coating (22) can be from 2 μm to 4 μm, preferably any value or a range between any two of 2 μm, 2.5 μm, 3 μm, 3.5 μm, and 4 μm. The solid electrolyte material may include one or more of LLZO (lithium lanthanum zirconium oxide), LLZTO (lithium lanthanum zirconium tantalum oxide), LLTO (lithium lanthanum titanium oxide), LAGP (lithium aluminum germanium phosphate), Li2ZrF6, Li2ZrCl6, and Li2AlF6. In addition to containing the solid electrolyte material, the second coating (22) may also include one or more of the following: dispersant, binder, and wetting agent. The dispersing agent may include one or more of sodium polyacrylate, polyethylene oxide, polyvinyl alcohol, methylcellulose, hydroxyethylcellulose, sodium carboxymethylcellulose, polyether silicone copolymer, polyoxyethylene alkanolamide, and ammonium polyacrylate. The binder may include one or more of acrylate, methacrylate, polymers obtained by copolymerizing styrene-butadiene rubber with olefins, polymers obtained by copolymerizing styrene-butadiene rubber with esters, polymers obtained by copolymerizing nitrile rubber with olefins, and polymers obtained by copolymerizing nitrile rubber with esters. The wetting agent may include one or more of polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether, and polyoxyethylene polyoxypropylene block copolymer. Furthermore, the particle size D50 of the solid electrolyte material can be from 0.1 μm to 3 μm, preferably within any value or a range between any two values ​​of 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, and 3 μm.

[0029] When the asymmetric solid electrolyte membrane of the present invention is assembled into a battery, the asymmetric solid electrolyte membrane is disposed between the positive electrode and the negative electrode, and the first coating (21) faces the positive electrode and the second coating (22) faces the negative electrode, thereby solving the problem of LATP degrading the performance of the negative electrode.

[0030] The following describes the preparation method of the asymmetric solid electrolyte membrane of the present invention. Although the above-mentioned asymmetric solid electrolyte membrane can be prepared, it should not be considered as a limitation. The detailed steps of the preparation method of the asymmetric solid electrolyte membrane are as follows:

[0031] First, a first slurry and a second slurry are respectively coated on a first surface of a base film and a second surface opposite to the first surface. The first slurry contains lithium titanium aluminum phosphate, and the second slurry contains a solid electrolyte material other than lithium titanium aluminum phosphate. Then, the film is dried to obtain an asymmetric solid electrolyte film.

[0032] The base film can be one or more of polyethylene base film and polypropylene base film. In addition, the thickness of the base film can be from 5 μm to 16 μm, preferably any value or a range between any two values ​​of 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, and 16 μm.

[0033] The first slurry may further include one or more of a dispersing agent, a binder, and a wetting agent. The dispersing agent of the first slurry may include one or more of sodium polyacrylate, polyethylene oxide, polyvinyl alcohol, methylcellulose, hydroxyethylcellulose, sodium carboxymethylcellulose, polyether silicone copolymer, polyoxyethylene alkanolamide, and ammonium polyacrylate. The binder of the first slurry may include one or more of acrylates, methacrylates, polymers obtained by copolymerizing styrene-butadiene rubber with olefins, polymers obtained by copolymerizing styrene-butadiene rubber with esters, polymers obtained by copolymerizing nitrile rubber with olefins, and polymers obtained by copolymerizing nitrile rubber with esters. The wetting agent of the first slurry may include one or more of polyoxyethylene alkylphenol ethers, polyoxyethylene fatty alcohol ethers, and polyoxyethylene polyoxypropylene block copolymers. Furthermore, given that the first slurry further includes a dispersing agent, a binder, and a wetting agent, the preparation method of the first slurry includes: adding a portion of the dispersing agent to water and stirring, then adding lithium titanium aluminum phosphate and stirring to obtain a mixture; grinding the mixture, and then sequentially adding another portion of the dispersing agent, binder, and wetting agent while stirring. Furthermore, the first slurry can be an aqueous slurry; its solid content can be 40% to 50%, preferably any value or a range between any two of 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, and 50%; its viscosity can be 10 mPa·s to 50 mPa·s, preferably any value or a range between any two of 10 mPa·s, 15 mPa·s, 20 mPa·s, 25 mPa·s, 30 mPa·s, 35 mPa·s, 40 mPa·s, 45 mPa·s, and 50 mPa·s; and its pH can be 7 to 10, preferably any value or a range between any two of 7, 7.5, 8, 8.5, 9, 9.5, and 10. In addition, the particle size D50 of lithium titanium aluminum phosphate can be from 0.1 μm to 3 μm, preferably any value or a range between any two values ​​of 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm.

[0034] The second slurry may further include one or more of a dispersing agent, a binder, and a wetting agent. The dispersing agent of the second slurry may include one or more of sodium polyacrylate, polyethylene oxide, polyvinyl alcohol, methylcellulose, hydroxyethylcellulose, sodium carboxymethylcellulose, polyether silicone copolymer, polyoxyethylene alkanolamide, and ammonium polyacrylate. The binder of the second slurry may include one or more of acrylates, methacrylates, polymers obtained by copolymerizing styrene-butadiene rubber with olefins, polymers obtained by copolymerizing styrene-butadiene rubber with esters, polymers obtained by copolymerizing nitrile rubber with olefins, and polymers obtained by copolymerizing nitrile rubber with esters. The wetting agent of the second slurry may include one or more of polyoxyethylene alkylphenol ethers, polyoxyethylene fatty alcohol ethers, and polyoxyethylene polyoxypropylene block copolymers. Furthermore, given that the second slurry further includes a dispersing agent, a binder, and a wetting agent, the preparation method of the second slurry includes: adding a portion of the dispersing agent to water and stirring, then adding a solid electrolyte material and stirring to obtain a mixture; grinding the mixture, and then sequentially adding another portion of the dispersing agent, binder, and wetting agent while stirring. Furthermore, the second slurry can be an aqueous slurry; its solid content can be 40% to 50%, preferably any value or a range between any two of 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, and 50%; its viscosity can be 10 mPa·s to 50 mPa·s, preferably any value or a range between any two of 10 mPa·s, 15 mPa·s, 20 mPa·s, 25 mPa·s, 30 mPa·s, 35 mPa·s, 40 mPa·s, 45 mPa·s, and 50 mPa·s; and its pH can be 7 to 10, preferably any value or a range between any two of 7, 7.5, 8, 8.5, 9, 9.5, and 10. In addition, the solid electrolyte material may include one or more of LLZO (lithium lanthanum zirconium oxide), LLZTO (lithium lanthanum zirconium tantalum oxide), LLTO (lithium lanthanum titanium oxide), LAGP (lithium aluminum germanium phosphate), Li₂ZrF₆, Li₂ZrCl₆, and Li₂AlF₆. Furthermore, the particle size D50 of the solid electrolyte material can be from 0.1 μm to 3 μm, preferably within any value or a range between any two of the following: 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, and 3 μm.

[0035] The invention will be illustrated here by way of the following examples.

[0036] Example 1

[0037] The diaphragm in this embodiment has a base film thickness of 9 μm and a double-sided coating, with one side coated with LATP and the other side coated with Al2O3, each coating having a thickness of 2 μm.

[0038] Add 1 wt% of dispersant to deionized water, stir until homogeneous, then add LATP or Al2O3, grind, add 4 wt% of dispersant, then add adhesive and wetting agent, stir until homogeneous to obtain LATP or Al2O3 slurry with a solid content of 40%, and finally coat it on both sides of the base membrane and dry to obtain a membrane with a coated structure.

[0039] When assembling into a battery, the LATP coating faces the positive electrode, and the Al2O3 coating faces the negative electrode.

[0040] Example 2

[0041] The diaphragm in this embodiment has a base film thickness of 9 μm and a double-sided coating, with one side coated with LATP and the other side coated with LLZTO, each coating having a thickness of 2 μm.

[0042] Add 1 wt% of dispersant to deionized water, stir until homogeneous, then add LATP or LLZTO, grind, add 4 wt% of dispersant, then add adhesive and wetting agent, stir until homogeneous to obtain LATP or LLZTO slurry with a solid content of 40%, and finally coat it on both sides of the base membrane and dry to obtain a membrane with a coated structure.

[0043] When assembling into a battery, the LATP coating faces the positive electrode, and the LLZTO coating faces the negative electrode.

[0044] Example 3

[0045] The diaphragm in this embodiment has a base film thickness of 9 μm and a double-sided coating, with one side coated with LATP and the other side coated with LLTO, each coating having a thickness of 2 μm.

[0046] Add 1 wt% of dispersant to deionized water, stir until homogeneous, then add LATP or LLTO, grind, add 4 wt% of dispersant, then add adhesive and wetting agent, stir until homogeneous to obtain LATP or LLTO slurry with a solid content of 40%, and finally coat it on both sides of the base membrane and dry to obtain a membrane with a coated structure.

[0047] When assembling into a battery, the LATP coating faces the positive electrode, and the LLTO coating faces the negative electrode.

[0048] Example 4

[0049] The diaphragm in this embodiment has a base film thickness of 9 μm and a double-sided coating, with one side coated with LATP and the other side coated with LLZO, each coating having a thickness of 2 μm.

[0050] Add 1 wt% of dispersant to deionized water, stir until homogeneous, then add LATP or LLZO, grind, add 4 wt% of dispersant, then add adhesive and wetting agent, stir until homogeneous to obtain LATP or LLZO slurry with a solid content of 40%, and finally coat it on both sides of the base membrane and dry to obtain a membrane with a coated structure.

[0051] When assembling into a battery, the LATP coating faces the positive electrode, and the LLZO coating faces the negative electrode.

[0052] Example 5

[0053] The diaphragm in this embodiment has a base film thickness of 9 μm and a double-sided coating, with one side coated with LATP and the other side coated with Li2ZrF6, each coating having a thickness of 2 μm.

[0054] Add 1 wt% of dispersant to deionized water, stir until homogeneous, then add LATP or Li2ZrF6, grind, add 4 wt% of dispersant, then add adhesive and wetting agent, stir until homogeneous to obtain LATP or Li2ZrF6 slurry with a solid content of 40%, and finally coat it on both sides of the base membrane and dry to obtain a membrane with a coated structure.

[0055] When assembling into a battery, the LATP coating faces the positive electrode, and the Li2ZrF6 coating faces the negative electrode.

[0056] Comparative Example 1

[0057] The diaphragm in this comparative example has a base film thickness of 9 μm and a double-sided coating, with LATP coated on one side and LATP also coated on the other side, each coating having a thickness of 2 μm.

[0058] Add 1 wt% of dispersant to deionized water, stir until homogeneous, then add LATP, grind, add 4 wt% of dispersant, then add adhesive and wetting agent, stir until homogeneous to obtain LATP slurry with 40% solid content, finally coat both sides of the base membrane and dry to obtain a membrane with a coated structure.

[0059] When assembled into a battery, the two LATP coatings face the positive and negative electrodes, respectively.

[0060] Comparative Example 2

[0061] The diaphragm in this comparative example has a base film thickness of 9 μm and no coating.

[0062] Comparative Example 3

[0063] The diaphragm in this comparative example has a base film thickness of 9 μm and a double-sided coating, with LLTO coated on one side and LLTO coated on the other side, each coating having a thickness of 2 μm.

[0064] Add 1 wt% of dispersant to deionized water, stir until homogeneous, then add LLTO, grind, add 4 wt% of dispersant, then add adhesive and wetting agent, stir until homogeneous to obtain LLTO slurry with 40% solid content, finally coat both sides of the base membrane and dry to obtain a membrane with a coated structure.

[0065] When assembled into a battery, the two LLTO coatings face the positive and negative electrodes, respectively.

[0066] Comparative Example 4

[0067] The diaphragm in this comparative example has a base film thickness of 9 μm and a double-sided coating, with LLZO coated on one side and LLZO coated on the other side, each coating having a thickness of 2 μm.

[0068] Add 1 wt% of dispersant to deionized water, stir until homogeneous, then add LLZO, grind, add 4 wt% of dispersant, then add adhesive and wetting agent, stir until homogeneous to obtain LLZO slurry with 40% solid content, finally coat both sides of the base membrane and dry to obtain a membrane with a coated structure.

[0069] When assembled into a battery, the two LLZO coatings face the positive and negative electrodes, respectively.

[0070] Comparative Example 5

[0071] The diaphragm in this comparative example has a base film thickness of 9 μm and a double-sided coating, with one side coated with Li2ZrF6 and the other side also coated with Li2ZrF6, each coating having a thickness of 2 μm.

[0072] Add 1 wt% of dispersant to deionized water, stir until homogeneous, then add Li2ZrF6, grind, add 4 wt% of dispersant, then add adhesive and wetting agent, stir until homogeneous to obtain Li2ZrF6 slurry with 40% solid content, finally coat both sides of the base membrane and dry to obtain a membrane with a coated structure.

[0073] When assembled into a battery, the two Li2ZrF6 coatings face the positive and negative electrodes, respectively.

[0074] It should be noted that when dispersing agents, adhesives, and wetting agents are mentioned in the above embodiments and comparative examples, the dispersing agents, adhesives, and wetting agents used are all of the same type and in the same amount. However, this is not the core spirit protected by this invention, and therefore there is no need to describe it in detail in the above embodiments and comparative examples, but it is specifically stated here.

[0075] In Table 1, low-temperature discharge refers to the capacity retention rate of 1C discharge at -20℃, high-temperature storage refers to the capacity retention rate and recovery rate of the battery after 7 days of high-temperature storage at 55℃, low-temperature cycling refers to the number of cycles at -10℃ with 0.5C charge and discharge to reach 80% of the capacity retention rate, and high-temperature cycling refers to the capacity retention rate after 250 cycles of 1C charge and discharge at 45℃.

[0076] Based on the superior performance of Examples 1 to 5 compared to Comparative Examples 1 to 5, it can be seen that the asymmetric coating structure can provide better battery performance. Based on the superior performance of Examples 2 to 5 compared to Example 1, it can be seen that the use of LATP combined with non-LATP solid electrolyte materials in the asymmetric coating structure can provide better battery performance.

[0077] Based on the superior performance of Example 3 compared to Comparative Examples 1 and 3, it can be seen that using LATP in combination with LLTO in an asymmetric coating structure can provide unexpected levels of battery performance. Based on the superior performance of Example 4 compared to Comparative Examples 1 and 4, it can be seen that using LATP in combination with LLZO in an asymmetric coating structure can provide unexpected levels of battery performance. Based on the superior performance of Example 5 compared to Comparative Examples 1 and 5, it can be seen that using LATP in combination with Li₂ZrF₆ in an asymmetric coating structure can provide unexpected levels of battery performance.

[0078] Table 1

[0079] The above content involving common knowledge will not be described in detail, as those skilled in the art will understand.

[0080] The above descriptions are merely some specific embodiments of the present invention and are not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. An asymmetric solid electrolyte membrane, characterized in that, include: A base film, a first coating, and a second coating, the base film having a first surface and a second surface opposite to the first surface, the first coating being formed on the first surface of the base film and comprising lithium aluminum titanium phosphate, and the second coating being formed on the second surface of the base film and comprising a solid electrolyte material other than lithium aluminum titanium phosphate.

2. The asymmetric solid electrolyte membrane according to claim 1, characterized in that, The solid electrolyte material includes one or more of the following: lithium lanthanum zirconium oxide, lithium lanthanum zirconium tantalum oxide, lithium lanthanum titanium oxide, lithium germanium aluminum phosphate, Li2ZrF6, Li2ZrCl6, and Li2AlF6.

3. The asymmetric solid electrolyte membrane according to claim 1, characterized in that, The thickness of the base film is 5 μm to 16 μm, the thickness of the first coating is 2 μm to 4 μm, and the thickness of the second coating is 2 μm to 4 μm.

4. The asymmetric solid electrolyte membrane according to claim 1, characterized in that, The base film is one or more of polyethylene base film and polypropylene base film.

5. The asymmetric solid electrolyte membrane according to claim 2, characterized in that, The first coating has a lithium titanium aluminum phosphate particle size D50 of 0.1 μm to 3 μm, and the second coating has a solid electrolyte material particle size D50 of 0.1 μm to 3 μm.

6. A battery, characterized in that, include: A positive electrode, a negative electrode, and a separator, the separator being disposed between the positive electrode and the negative electrode and comprising an asymmetric solid electrolyte membrane as described in any one of claims 1 to 5, wherein a first coating faces the positive electrode and a second coating faces the negative electrode.

7. A method for preparing an asymmetric solid electrolyte membrane, characterized in that, include: A first slurry and a second slurry are respectively coated on a first surface and a second surface opposite to the first surface of a base film. The first slurry contains lithium aluminum titanium phosphate, and the second slurry contains a solid electrolyte material other than lithium aluminum titanium phosphate. The asymmetric solid electrolyte membrane is obtained by drying.

8. The method for preparing the asymmetric solid electrolyte membrane according to claim 7, characterized in that, The solid electrolyte material includes one or more of the following: lithium lanthanum zirconium oxide, lithium lanthanum zirconium tantalum oxide, lithium lanthanum titanium oxide, lithium germanium aluminum phosphate, Li2ZrF6, Li2ZrCl6, and Li2AlF6.

9. The method for preparing the asymmetric solid electrolyte membrane according to claim 7, characterized in that, The first slurry further includes one or more of a dispersing agent, a binder, and a wetting agent, and the second slurry further includes one or more of a dispersing agent, a binder, and a wetting agent.

10. The method for preparing the asymmetric solid electrolyte membrane according to claim 9, characterized in that, The dispersing agent of the first slurry includes one or more of sodium polyacrylate, polyethylene oxide, polyvinyl alcohol, methylcellulose, hydroxyethylcellulose, sodium carboxymethylcellulose, polyether silicone copolymer, polyoxyethylene alkanolamide, and ammonium polyacrylate. The binder of the first slurry includes one or more of acrylate, methacrylate, polymer obtained by copolymerization of styrene-butadiene rubber and olefins, polymer obtained by copolymerization of styrene-butadiene rubber and esters, polymer obtained by copolymerization of nitrile rubber and olefins, and polymer obtained by copolymerization of nitrile rubber and esters. The wetting agent of the first slurry includes one or more of polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether, and polyoxyethylene polyoxypropylene block copolymer.

11. The method for preparing an asymmetric solid electrolyte membrane according to claim 9, characterized in that, The dispersing agent of the second slurry includes one or more of sodium polyacrylate, polyethylene oxide, polyvinyl alcohol, methylcellulose, hydroxyethylcellulose, sodium carboxymethylcellulose, polyether silicone copolymer, polyoxyethylene alkanolamide, and ammonium polyacrylate. The binder of the second slurry includes one or more of acrylate, methacrylate, polymer obtained by copolymerization of styrene-butadiene rubber and olefins, polymer obtained by copolymerization of styrene-butadiene rubber and esters, polymer obtained by copolymerization of nitrile rubber and olefins, and polymer obtained by copolymerization of nitrile rubber and esters. The wetting agent of the second slurry includes one or more of polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether, and polyoxyethylene polyoxypropylene block copolymer.

12. The method for preparing the asymmetric solid electrolyte membrane according to claim 7, characterized in that, The first slurry is an aqueous slurry with a solid content of 40% to 50%, a viscosity of 10 mPa·s to 50 mPa·s, and a pH of 7 to 10; the second slurry is an aqueous slurry with a solid content of 40% to 50%, a viscosity of 10 mPa·s to 50 mPa·s, and a pH of 7 to 10.

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