Composite solid electrolyte membrane, preparation method and battery

Abstract

The invention relates to the technical field of batteries, in particular to a composite solid-state electrolyte membrane which comprises a halide solid-state electrolyte layer, a first solid-state electrolyte layer and a sulfide solid-state electrolyte layer arranged between the halide solid-state electrolyte layer and the first solid-state electrolyte layer. The first solid electrolyte layer comprises a first solid electrolyte, and the first solid electrolyte comprises a borohydride solid electrolyte and / or a carbon borohydride solid electrolyte. The electrochemical stability and the ionic conductivity of the composite solid electrolyte membrane can be improved, and the cycle performance and the rate capability of the battery can be improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a composite solid electrolyte membrane, its preparation method, and a battery. Background Technology

[0002] All-solid-state batteries are lithium-ion batteries that use solid electrolytes instead of liquid electrolytes. Due to their advantages such as high safety performance, high energy density, and wide operating temperature range, all-solid-state batteries have broad application prospects, such as new energy vehicles, energy storage systems, and consumer electronics. They have become a research hotspot in the field of lithium-ion batteries and have attracted much attention.

[0003] With the continuous development of solid-state battery technology, solid electrolyte membranes prepared from single solid electrolytes can no longer meet the needs. Sulfide solid electrolytes and halide solid electrolytes have high ionic conductivity, but poor compatibility with the positive and negative electrodes. Therefore, there is an urgent need to develop a solid electrolyte membrane that can achieve the synergistic effect of "high voltage resistance on the positive electrode side and reduction resistance on the negative electrode side", while also taking into account the overall high ionic conductivity. Summary of the Invention

[0004] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is how to improve the compatibility between solid electrolyte and positive and negative electrodes and improve ion conductivity.

[0005] To achieve the above objectives, the present invention provides a composite solid electrolyte membrane, comprising a halide solid electrolyte layer, a first solid electrolyte layer, and a sulfide solid electrolyte layer disposed between the halide solid electrolyte layer and the first solid electrolyte layer, wherein the first solid electrolyte layer comprises a first solid electrolyte, and the first solid electrolyte comprises a borohydride solid electrolyte and / or a carborohydride solid electrolyte.

[0006] In some embodiments, the thickness ratio of the halide solid electrolyte layer to the sulfide solid electrolyte layer is 1:1 to 1:12;

[0007] And / or, the thickness ratio of the first solid electrolyte layer to the sulfide solid electrolyte layer is 1:1 to 1:12.

[0008] In some embodiments, the composite solid electrolyte membrane further includes a first mixed layer disposed between the halide solid electrolyte layer and the sulfide solid electrolyte layer, the first mixed layer comprising the halide solid electrolyte and the sulfide solid electrolyte.

[0009] In some embodiments, the composite solid electrolyte membrane further includes a second mixing layer disposed between the sulfide solid electrolyte layer and the first solid electrolyte layer, the second mixing layer including the first solid electrolyte and the sulfide solid electrolyte.

[0010] In some embodiments, the first mixing layer is a multilayer structure, and in each layer of the first mixing layer, the mass ratio w1 of the halide solid electrolyte to the sulfide solid electrolyte satisfies: w1 = 1:34 to 1:1.

[0011] In some embodiments, in the direction from the halide solid electrolyte layer to the sulfide solid electrolyte layer, the mass percentage of the halide solid electrolyte decreases and the mass percentage of the sulfide solid electrolyte increases in the adjacent first mixed layer.

[0012] In some embodiments, the second mixing layer is a multilayer structure, and in each layer of the second mixing layer, the mass ratio w2 of the first solid electrolyte to the sulfide solid electrolyte satisfies: w2 = 1:49 to 1:1.

[0013] In some embodiments, in the direction from the first solid electrolyte layer to the sulfide solid electrolyte layer, the mass percentage of the first solid electrolyte decreases and the mass percentage of the sulfide solid electrolyte increases in the adjacent second mixed layer.

[0014] The present invention also provides a method for preparing the above-mentioned composite solid electrolyte membrane, comprising the following steps:

[0015] S1. Preparation of sulfide solid electrolyte layer;

[0016] S2. Prepare a halide solid electrolyte layer on one side of the sulfide solid electrolyte layer or prepare the first mixed layer and the halide solid electrolyte layer in sequence.

[0017] S3. Prepare a first solid electrolyte layer on the other side of the sulfide solid electrolyte layer or prepare a second mixed layer and a first solid electrolyte layer in sequence to obtain a composite solid electrolyte membrane.

[0018] The present invention also provides a lithium battery, comprising the above-mentioned composite solid electrolyte membrane, a positive electrode, and a negative electrode, wherein the positive electrode, the negative electrode, and the composite solid electrolyte membrane are stacked, and the composite solid electrolyte membrane is disposed between the positive electrode and the negative electrode; and the halide solid electrolyte layer is disposed close to the positive electrode, and the first solid electrolyte layer is disposed close to the negative electrode.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] This invention prepares a composite solid electrolyte membrane with high lithium-ion conductivity and good electrochemical stability. When applied to batteries, it can achieve the synergistic effect of "high voltage resistance on the positive electrode side and reduction resistance on the negative electrode side", which can effectively improve the cycle performance and rate performance of the battery. Detailed Implementation

[0021] Reference will now be made to detailed embodiments of this application, one or more of which are described below. Each embodiment is provided for explanation and not for limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to this application without departing from the general inventive concept. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.

[0022] Therefore, this application is intended to cover such modifications and variations falling within the scope of the appended claims and their equivalents. Other objects, features, and aspects of this application are disclosed in or will be apparent from the following detailed description. It will be understood by those skilled in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of this application.

[0023] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0024] In this application, unless otherwise specified, the numerical ranges involved in the improvements relative to the prior art are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0025] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0026] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0027] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0028] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0029] In current production processes, a single solid electrolyte membrane cannot simultaneously satisfy both good compatibility with positive and negative electrodes and high ionic conductivity. Therefore, there is an urgent need for a composite solid electrolyte membrane that can solve these problems at the same time.

[0030] In a first aspect, the present invention provides a composite solid electrolyte membrane, comprising a halide solid electrolyte layer, a sulfide solid electrolyte layer, and a first solid electrolyte layer, wherein the sulfide solid electrolyte layer is disposed between the halide solid electrolyte layer and the first solid electrolyte layer, and the first solid electrolyte layer comprises a first solid electrolyte, which comprises a borohydride solid electrolyte and / or a carborohydride solid electrolyte.

[0031] By setting a halide solid electrolyte layer and a first solid electrolyte layer on both sides of the sulfide solid electrolyte layer, the electrochemical stability and ionic conductivity of the composite solid electrolyte membrane can be improved simultaneously.

[0032] This invention prepares a composite solid electrolyte membrane with high lithium-ion conductivity and good electrochemical stability. When applied to batteries, it can achieve the synergistic effect of "high voltage resistance on the positive electrode side and reduction resistance on the negative electrode side", which can effectively improve the cycle performance and rate performance of the battery.

[0033] In some embodiments, the thickness ratio of the halide solid electrolyte layer to the sulfide solid electrolyte layer is 1:1 to 1:12. For example, it can be selected as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11 or 1:12, etc., and is not limited thereto. In practical applications, it can be reasonably selected according to the needs.

[0034] In some embodiments, the thickness ratio of the first solid electrolyte layer to the sulfide solid electrolyte layer is 1:1 to 1:12. For example, it can be selected as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11 or 1:12, etc., and is not limited thereto. In practical applications, it can be reasonably selected according to the needs.

[0035] In some embodiments, the first solid electrolyte includes Li(BH4) and LiB. n H n (n = 10, 12), LiCB n H n+1 (n = 9, 11), LiB11 H 14 Any one of Li(BH4) and its derivative-based solid electrolytes. It is understood that derivative-based solid electrolytes refer to those synthesized by reacting Li(BH4), LiB... n H n (n = 10, 12), LiCB n H n+1 (n = 9, 11), LiB 11 H 14 Solid electrolytes that are doped with metallic or non-metallic elements without altering their lithium-ion transport capabilities.

[0036] In some embodiments, the sulfide solid electrolyte includes Li2S-P2S5 and Li2S-P2S5-MS. x (where M is Si, Ge, and Sn and 0 ≤ x ≤ 2), Li 24.4 Si 0.4 P 0.6 S4, Li 10 GeP2S 11.7 O 0.24 Li 9.6 P 24 S 12 Li7P 24 S 11 Li9P 24 S9O 24 Li 10.245 Si 1.245 P 1.65 S 12 Li 9.81 Sn 0.81 P 2.19 S 12 Li 10 (Si 0.5 Ge 0.5 P2S 12 Li (Ge 0.5 Sn 0.5 P2S 12 Li 10 GeP2S 12 Li6PS5X (where X is Cl, Br, or I), Li7P2S8I, Li 10.245 Ge 1.245 P 1.65 S 12 Li 24.25 Ge 0.25 P 0.75 S4, Li 10 SnP2S 12 Li 10 SiP2S 12 Li9.54 Si 1.74 P 1.44 S 11.7 Cl 0.24 One of (1-x)P2S5-xLi2S (where 0.5≤x≤0.7) and combinations thereof.

[0037] In some embodiments, the ionic conductivity of the sulfide solid electrolyte is 10. -7 S / cm~1S / cm.

[0038] In some embodiments, the halide solid electrolyte includes Li a M b X c N d M includes one or more of the basic metal elements, such as Zr, Hf, In, Sc, Y, La, Ce, Pr, Nb, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. M also includes doped metal elements, used in conjunction with the aforementioned basic metal elements, such as one or more of Nb, Ta, Al, La, Mg, Ca, Ba, and Ag. X includes one or more of F, Cl, Br, and I. N includes one or more of O and S, and satisfies a + mb = c + nd, where m and n are the weighted valences of M and N, respectively, and 1 ≤ a ≤ 4.

[0039] For example, the halide solid electrolyte particles can be Li₂ZrCl₆, Li₂ZrCl₅F, or Li₂ZrCl₆. 5.5 O 0.25 The composite solid electrolyte membrane comprises at least one of the following: Li3InCl6, Li3YCl6, Li2HfCl6, LiInBr4, Li3InBr6, Li3LaI6, Li3LuCl6, and Li3ErCl6. In some embodiments, the composite solid electrolyte membrane further comprises a first mixed layer disposed between the halide solid electrolyte layer and the sulfide solid electrolyte layer, the first mixed layer comprising the halide solid electrolyte and the sulfide solid electrolyte.

[0040] In some embodiments, the first mixing layer is a multi-layer structure, and in each layer of the first mixing layer, the mass ratio w1 of the halide solid electrolyte to the sulfide solid electrolyte satisfies: w1 = 1:34 to 1:1. For example, it can be selected as 1:1, 1:5, 1:10, 1:15, 1:20, 1:25, 1:30 or 1:34, etc., and is not limited thereto. In practical applications, it can be reasonably selected according to the needs.

[0041] In some implementations, w1 is preferably 1:34 to 1:8.

[0042] In some embodiments, in the direction from the halide solid electrolyte layer to the sulfide solid electrolyte layer, the mass percentage of halide solid electrolyte decreases and the mass percentage of sulfide solid electrolyte increases in adjacent first mixed layers. For example, if the layers in the direction from the halide solid electrolyte layer to the sulfide solid electrolyte layer are sequentially the first-1 mixed layer, the first-2 mixed layer, ..., the first-N mixed layers, then the mass percentage of halide solid electrolyte in the first-1 mixed layer is greater than the mass percentage of halide solid electrolyte in the first-2 mixed layer, which is greater than the mass percentage of halide solid electrolyte in the first-3 mixed layer, ..., which is greater than the mass percentage of halide solid electrolyte in the first-N mixed layers.

[0043] In some embodiments, the number of first hybrid layers is 1 to 5. Increasing the number of first hybrid layers is beneficial for gradient design and for continuously improving the lithium-ion transport efficiency of the composite solid electrolyte membrane. However, it increases the difficulty of the process and the difficulty of controlling the thickness of the composite solid electrolyte membrane.

[0044] In some embodiments, the composite solid electrolyte membrane further includes a second mixing layer disposed between the sulfide solid electrolyte layer and the first solid electrolyte layer, the second mixing layer including the first solid electrolyte and the sulfide solid electrolyte.

[0045] In some embodiments, the second mixing layer is a multi-layer structure, and in each layer of the second mixing layer, the mass ratio w2 of the first solid electrolyte to the sulfide solid electrolyte satisfies: w2 = 1:49 to 1:1. Exemplarily, it can be selected as 1:1, 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, or 1:49, etc., and is not limited thereto. In practical applications, a reasonable selection can be made according to the needs.

[0046] In some implementations, w2 is preferably 1:49 to 1:12.

[0047] In some embodiments, and in the direction from the first solid electrolyte layer to the sulfide solid electrolyte layer, the mass percentage of the first solid electrolyte decreases and the mass percentage of the sulfide solid electrolyte increases in the adjacent second mixed layer.

[0048] In some embodiments, the number of layers in the second mixing layer is 1 to 5, preferably 3 to 4. Increasing the number of layers in the second mixing layer is beneficial for gradient design and for continuously improving the lithium-ion transport efficiency of the composite solid electrolyte membrane. However, it increases the difficulty of the process and the difficulty of controlling the thickness of the composite solid electrolyte membrane.

[0049] In some embodiments, when the composite solid electrolyte membrane includes both a plurality of first mixed layers and a plurality of second mixed layers, the number of layers in both is the same.

[0050] In some embodiments, when the composite solid electrolyte membrane includes both a plurality of first mixed layers and a plurality of second mixed layers, the number of layers in the two mixtures is different.

[0051] In some embodiments, the halide solid electrolyte layer, the sulfide solid electrolyte layer, the first solid electrolyte layer, the first mixed layer, and the second mixed layer all contain an adhesive, which includes at least one of styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polyurethane (PU), polyacrylic acid (PAA), ethylene-propylene-diene monomer (EPDM), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), fluororubber (FKM), or nitrile rubber (NBR).

[0052] Secondly, the present invention also provides a method for preparing the above-mentioned composite solid electrolyte, comprising the following steps:

[0053] S1. Preparation of sulfide solid electrolyte layer;

[0054] S2. Prepare a halide solid electrolyte layer on one side of the sulfide solid electrolyte layer or prepare the first mixed layer and the halide solid electrolyte layer in sequence.

[0055] S3. Prepare a first solid electrolyte layer on the other side of the sulfide solid electrolyte layer or prepare a second mixed layer and a first solid electrolyte layer in sequence to obtain a composite solid electrolyte membrane.

[0056] It is understandable that the preparation of the halide solid electrolyte layer and the first solid electrolyte layer can be done by wet coating or by dry preparation, and then composited.

[0057] In some embodiments, the above preparation method further includes:

[0058] Step S4: Perform isostatic densification treatment on the composite solid electrolyte membrane.

[0059] Specifically, the composite solid electrolyte membrane is placed in an isostatic pressing device to densify it.

[0060] In some implementations, the isostatic pressing temperature is 50°C to 80°C. For example, it can be selected as 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, etc., and is not limited thereto. In actual applications, a reasonable selection can be made according to the needs.

[0061] In some implementations, the isostatic pressure is 300MPa to 600MPa. For example, it can be selected as 300MPa, 350MPa, 400MPa, 450MPa, 500MPa, 550MPa or 600MPa, etc., and is not limited thereto. In actual applications, it can be reasonably selected according to the needs.

[0062] In some embodiments, the isostatic holding time is 10s to 5min, and for example, it can be selected as 10s, 30s, 50s, 1min, 2min, 3min, 4min or 5min.

[0063] In some implementations, step S2 further includes the following steps:

[0064] S211. Several sulfide solid electrolyte regions are formed on the surface of the sulfide solid electrolyte layer by dot coating, which are the first regions. S212. The halide solid electrolyte slurry is coated on the remaining areas of the sulfide solid electrolyte layer surface except for the first regions, ensuring that the first regions are exposed, to prepare the first mixed layer.

[0065] In some embodiments, when the first hybrid layer is a multilayer structure, step S2 further includes the following steps:

[0066] S213. Continue to apply sulfide solid electrolyte to the exposed first area to form a second area, and apply halide solid electrolyte slurry to the remaining areas except the second area to form a second layer of the first mixed layer.

[0067] Repeat the above operation until the desired number of layers is reached. In some embodiments, step S2 further includes the following step:

[0068] S221. Several sulfide solid electrolyte regions are formed on the surface of the sulfide solid electrolyte layer by dot coating, which is the first region.

[0069] S222. The first solid electrolyte slurry is coated on the surface of the sulfide solid electrolyte layer, except for the first region, ensuring that the first region is exposed, to prepare the second mixed layer.

[0070] In some embodiments, it is also necessary to prepare a multilayer second hybrid layer, and step two further includes the following steps:

[0071] S223. Continue to apply sulfide solid electrolyte to the exposed first area to form a second area, and then apply the first solid electrolyte slurry to the remaining areas except for the second area. Repeat the above operation until the required number of layers is achieved.

[0072] In some embodiments, the area ratio of the second sulfide solid electrolyte region to the sulfide solid electrolyte region is 1 to 9:10. For example, it can be selected as 1:10, 2:10, 3:10, 4:10, 5:10, 6:10, 7:10, 8:10 or 9:10, etc., and is not limited thereto. In practical applications, it can be reasonably selected according to the needs.

[0073] Thirdly, the present invention also provides a battery comprising the above-mentioned composite solid electrolyte membrane, a positive electrode, and a negative electrode, wherein the positive electrode, the negative electrode, and the composite solid electrolyte membrane are stacked, and the composite solid electrolyte membrane is disposed between the positive electrode and the negative electrode; and the halide solid electrolyte layer is disposed close to the positive electrode, and the first solid electrolyte layer is disposed close to the negative electrode.

[0074] In some embodiments, the positive electrode includes a positive current collector and a positive electrode layer disposed on at least one side surface of the positive current collector.

[0075] In some embodiments, the positive electrode layer includes a positive electrode active material, which includes a compound that can reversibly insert and deintercalate lithium ions.

[0076] In some embodiments, the positive electrode active material includes, but is not limited to, lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium nickel cobalt manganese oxide (LiNiaCobMncO2, where a+b+c=1, NCM), and lithium nickel cobalt aluminum oxide (LiNiaCobMncO2). 0.8 Co 0.15 Al 0.05O2, NCA, etc., or compounds substituted with one or more transition metals; lithium manganese oxides such as Li1+xMn2-xO4 (x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxides such as Li2CuO2; vanadium compounds such as LiV3O8, LiV3O4, V2O5, Cu2V2O7, etc.; lithium nickel oxides represented by the molecular formula LiNi1-xMxO2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, including at least one of the above elements, where x is 0.01 to 0.3); lithium nickel oxides represented by the molecular formula LiMn2-xMxO2 (where M is Co, Ni, Fe, C, etc., and M is Co, Ni, Fe, C, etc., and M is C ... Lithium manganese composite oxides represented by r, Zn or Ta (where x is 0.01 to 0.1) or the molecular formula Li2Mn3MO8 (where M is Fe, Co, Ni, Cu or Zn); spinel-type lithium manganese composite oxides represented by LiNixMn2-xO4; Li in the formula LiMn2O4 is replaced by alkaline earth metal ions; LiNixCoyMn(1-xy)O2 (where x = 0.8, y = 0.1); disulfide compounds; Fe2(MoO4)3; lithium cobalt oxide; lithium iron phosphate; elemental sulfur; Li2Sn (n = 1), organic sulfur compounds or carbon-sulfur polymers ((C2Sx)n (x is 2.5 to 50, n is 2)); possibly including sulfur-based compounds, etc.

[0077] In some preferred embodiments, the continuous oxidation decomposition voltage U of the positive electrode active material is ≥4.5V; for example, the positive electrode active material includes one or more of lithium cobalt oxide, high-nickel ternary positive electrode material, lithium-rich manganese-based positive electrode material, and lithium nickel manganese oxide, which is beneficial to improving the energy density of the battery.

[0078] In some embodiments, the mass of the positive electrode active material accounts for 50% to 95% of the mass of the positive electrode active material layer.

[0079] In some embodiments, the positive electrode layer includes a positive electrode binder that enhances the bonding between positive electrode active material particles and also enhances the bonding between the positive electrode active material layer and the positive electrode current collector.

[0080] In some embodiments, the positive electrode binder may be selected from polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene-ethylene-butene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), and combinations thereof.

[0081] In some embodiments, the mass of the positive electrode binder accounts for 0.1% to 20% of the mass of the positive electrode active material layer.

[0082] In some embodiments, the positive electrode layer includes a positive electrode conductive agent that imparts conductivity to the electrode.

[0083] In some embodiments, the positive electrode conductive agent may include carbon-based materials, powdered nickel or other metal particles, or conductive polymers. Carbon-based materials may include particles such as carbon black, graphite, SuperP, acetylene black (such as KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, poly(3,4-ethylenedioxythiophene)polysulfonated styrene, etc.

[0084] In some embodiments, the mass of the conductive agent accounts for 0.1% to 20% of the mass of the positive electrode active material layer.

[0085] In some embodiments, the mass of the conductive agent accounts for 0.1% to 20% of the mass of the positive electrode active material layer.

[0086] In some embodiments, the positive electrode active material layer provided in this application further includes a fast ion conductor to improve the ionic conductivity of the positive electrode active material layer. This application does not limit the type of fast ion conductor, which can be an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte, a lithium salt, etc.

[0087] In some embodiments, the oxide solid electrolyte may include one or more garnet ceramics, LISICON-type oxides, NASICON-type oxides, and perovskite-type ceramics. For example, one or more garnet ceramics may be selected from the group consisting of: Li 6.5 La 24 Zr 1.75 Te 0.25 O 12 、Li7La 24 Zr2O 12 Li 6.2 Ga 0.24 La 2.95 Rb 0.05 Zr2O 12 Li 6.85 La 2.9 Ca 0.1 Zr 1.75 Nb 0.25 O 12 Li 6.25 Al 0.25 La 24 Zr2O 12 Li 6.75 La 24 Zr 1.75 Nb 0.25 O 12 Li6.75 La 24 Zr 1.75 Nb 0.25 O 12 And combinations thereof. One or more LISICON-type oxides may be selected from the group consisting of: Li 14 Zn(GeO4)4, Li 24+x (P 1-x Si x O4 (where 0 < x < 1), Li 24+x Ge x V 1-x O4 (where 0 < x < 1) and combinations thereof. One or more NASICON-type oxides can be produced from LiMM′(PO4). 24 Defined where M and M′ are independently selected from Al, Ge, Ti, Sn, Hf, Zr, and La. For example: in some variants, one or more NASICON-type oxides may be selected from the group consisting of: Li 1+x Al x Ge 2-x (PO4) 24 (LAGP) (where 0 ≤ x ≤ 2), Li 1+x Al x Ti 2-x (PO4) 24 (LATP) (where 0 ≤ x ≤ 2), Li 1+x Y x Zr 2-x (PO4) 24 (LYZP) (where 0≤x≤2), Li 1.24 Al 0.24 Ti 1.7 (PO4) 24 LiTi2(PO4) 24 LiGeTi(PO4) 24 LiGe2(PO4) 24 LiHf2(PO4) 24 And combinations thereof. One or more perovskite ceramics may be selected from the group consisting of: Li 24.24 La 0.524 TiO 24 LiSr 1.65 Zr 1.24 Ta 1.7 O9、Li 2x-y Sr 1-x Ta y Zr 1-y O 24 (where x = 0.75y and 0.60 < y < 0.75), Li 24 / 8Sr 7 / 16 Nb 24 / 4 Zr 1 / 4 O 24 Li 24x La (2 / 24-x) TiO 24 (where 0 < x < 0.25) and combinations thereof. In one variant, one or more oxide-based materials may have a value greater than or equal to about 10. -5 S / cm to less than or equal to approximately 10 -1 Ionic conductivity in S / cm.

[0088] In some embodiments, the sulfide solid electrolyte may include one or more sulfide-based materials selected from the group consisting of: Li2S-P2S5, Li2S-P2S5-MS x (where M is Si, Ge, and Sn and 0 ≤ x ≤ 2), Li 24.4 Si 0.4 P 0.6 S4, Li 10 GeP2S 11.7 O 0.24 Li 9.6 P 24 S 12 Li7P 24 S 11 Li9P 24 S9O 24 Li 10.245 Si 1.245 P 1.65 S 12 Li 9.81 Sn 0.81 P 2.19 S 12 Li 10 (Si 0.5 Ge 0.5 P2S 12 Li (Ge 0.5 Sn 0.5 P2S 12 Li 10 GeP2S 12 (LGPS), Li6PS5X (where X is Cl, Br, or I), Li7P2S8I, Li 10.245 Ge 1.245 P 1.65 S 12 Li 24.25 Ge 0.25 P 0.75 S4, Li 10 SnP2S 12 Li 10SiP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.24 (1-x)P₂S₅-xLi₂S (where 0.5 ≤ x ≤ 0.7) and combinations thereof. In one variant, one or more sulfide-based materials may have a content greater than or equal to about 10 -7 Ionic conductivity from S / cm to less than or equal to about 1 S / cm.

[0089] In some embodiments, the halide solid electrolyte includes Li a M b X c N d M includes one or more of the basic metal elements, such as Zr, Hf, In, Sc, Y, La, Ce, Pr, Nb, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. M also includes doped metal elements, used in conjunction with the aforementioned basic metal elements, such as one or more of Nb, Ta, Al, La, Mg, Ca, Ba, and Ag. X includes one or more of F, Cl, Br, and I. N includes one or more of O and S, and satisfies a + mb = c + nd, where m and n are the weighted valences of M and N, respectively, and 1 ≤ a ≤ 4.

[0090] In some embodiments, the solid electrolyte includes a halide solid electrolyte. Halide solid electrolytes have high ionic conductivity and, compared to sulfide solid electrolytes, better air stability, are less prone to decomposition, and do not produce toxic substances. Halide solid electrolytes are incompatible with most liquids and can undergo side reactions; therefore, dry processes are well-suited for batteries using halide solid electrolytes.

[0091] For example, the halide solid electrolyte particles can be Li₂ZrCl₆, Li₂ZrCl₅F, or Li₂ZrCl₆. 5.5 O 0.25 At least one of Li3InCl6, Li3YCl6, Li2HfCl6, LiInBr4, Li3InBr6, Li3LaI6, Li3LuCl6, and Li3ErCl6.

[0092] In some embodiments, the lithium salt includes LiNbO3 and Li4Ti5O. 12 At least one of Li2TiO3, LiAlO2, LiTaO3, LiMoO3, Li2RuO3 or Li2WO4.

[0093] In some embodiments, the mass of the fast ion conductor accounts for 0.1% to 40% of the mass of the positive electrode active material layer.

[0094] In some embodiments, the thickness of the positive electrode film is 50 μm to 300 μm. For example, the thickness of the positive electrode film can be 50 μm, 100 μm, 150 μm, 200 μm, 250 μm or 300 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0095] In some embodiments, the positive electrode can be prepared by wet or dry methods. The dry process involves uniformly mixing positive electrode active particles, positive electrode conductive agent, and positive electrode binder, then subjecting the mixture to fibrillation treatment. Under the fibrillation effect of the positive electrode binder, a self-supporting film is formed, and finally, it is rolled onto the surface of the positive electrode current collector. The wet process involves adding a solvent (such as NMP) to the positive electrode active particles, positive electrode conductive agent, and positive electrode binder to form a slurry. The slurry is then coated onto the surface of the positive electrode current collector using a coating machine and baked. In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode layer disposed on at least one side of the negative electrode current collector. The negative electrode current collector is, for example, copper foil or carbon-coated copper foil. The negative electrode layer can be disposed on one surface of the negative electrode current collector or simultaneously on both surfaces.

[0096] In some embodiments, the negative electrode layer includes a negative electrode active material, which is a material containing metal ions capable of intercalating or deintercalating lithium ions. Exemplary examples may be metallic materials (such as Li, Ag, Al, Bi, Cu, Ga, Ge, In, Ni, Pb, Sb, Si, Sn, Sr, Zn, etc., or alloys or compounds of the above metals, such as Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, TiO2-Li4Ti5O12, Li-Al alloys, Ag-C alloys, etc.), carbon materials (such as graphite including natural graphite / artificial graphite, carbon fibers, soft carbon, hard carbon, crystalline carbon, amorphous carbon, etc.), silicon compounds (such as silicon, silicon-carbon composites, etc.).

[0097] In some embodiments, the negative electrode can be a lithium-based negative electrode. For example, the negative electrode can be a lithium metal negative electrode. Alternatively, the negative electrode can also be a silicon-based negative electrode. For example, the negative electrode is made of a carbon-silicon composite and coated onto a copper foil that serves as the negative electrode current collector to form a negative electrode sheet.

[0098] In some implementations, the negative electrode can be an anode-free lithium metal solid-state battery. The negative electrode can be made of Ag-C alloy and coated on copper foil, which serves as the negative electrode current collector, to form a negative electrode sheet (or negative electrode side structure).

[0099] In some preferred embodiments, the negative electrode comprises lithium metal or a lithium-containing alloy, which is beneficial for improving the energy density of the battery.

[0100] In some embodiments, the mass percentage of the negative electrode active material included in the negative electrode layer can be 80% to 99%, for example, 80%, 85%, 90%, 95%, 97%, 99%, etc., preferably 95% to 97%.

[0101] In some embodiments, the negative electrode layer may also include a binder, exemplarily including polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc. This invention does not limit these applications.

[0102] In some embodiments, the negative electrode layer may also include conductive additives, such as carbon-based materials like graphite (natural or artificial graphite), carbon black (acetylene black or Ketjen black), carbon nanotubes, graphene, etc.; metal-based materials like metal powders (aluminum powder, nickel powder, etc.), metal oxides (titanium oxide, etc.), metal whiskers (alumina, oxidizing agents, etc.); conductive polymers like polyaniline, polypyrrole, polythiophene, etc.; and conductive fibers like carbon fibers, metal fibers, metal compound fibers, polymer fibers, etc. The conductive additive may also be one or a mixture of the above.

[0103] In some embodiments, the negative electrode can be prepared by wet or dry methods. The dry process involves uniformly mixing the negative electrode active particles, negative electrode conductive agent, and negative electrode binder, then subjecting the mixture to fibrillation treatment. Under the fibrillation effect of the negative electrode binder, a self-supporting film is formed, and finally, it is rolled onto the surface of the negative electrode current collector. The wet process involves adding a solvent (such as NMP) to the negative electrode active particles, negative electrode conductive agent, and negative electrode binder to form a slurry. The slurry is then coated onto the surface of the negative electrode current collector using a coating machine, and after drying, a negative electrode sheet is formed.

[0104] To better understand the above-mentioned objectives, features, and advantages of this application, the solutions of this application will be further described below through embodiments and comparative examples. Obviously, the embodiments in this specification are only one embodiment of this application, and not all embodiments.

[0105] Example 1

[0106] This embodiment provides a composite solid electrolyte membrane, including a halide solid electrolyte layer, a first mixed layer, a sulfide solid electrolyte layer, a second mixed layer, and a first solid electrolyte layer.

[0107] The halide solid electrolyte layer comprises a halide solid electrolyte Li3YCl6 and a binder styrene-butadiene rubber (SBR) in a mass ratio of 99.5:0.5. The thickness of the halide solid electrolyte layer is 10 μm.

[0108] The first mixed layer has a three-layer structure, with thicknesses of 3 μm, 2 μm, and 1 μm respectively from the halide solid electrolyte layer to the sulfide solid electrolyte layer. The mass ratios of the sulfide solid electrolyte to the halide solid electrolyte are 1:1, 10:1, and 20:1, respectively.

[0109] The sulfide solid electrolyte layer comprises a sulfide solid electrolyte Li6PS5Cl and a binder styrene-butadiene rubber (SBR) in a mass ratio of 99.5:0.5. The thickness of the sulfide solid electrolyte layer is 30 μm.

[0110] The second mixing layer has a three-layer structure. From the sulfide solid electrolyte layer to the first solid electrolyte layer, the thicknesses are 1 μm, 2 μm, and 3 μm, respectively. The mass ratios of the sulfide solid electrolyte to the first solid electrolyte are 49:1, 30:1, and 12:1, respectively.

[0111] The first solid electrolyte layer comprises a first solid electrolyte Li(BH4) and a binder styrene-butadiene rubber (SBR) in a mass ratio of 99.5:0.5. The thickness of the first solid electrolyte layer is 10 μm.

[0112] This embodiment also provides a method for preparing the above-mentioned composite solid electrolyte membrane, comprising the following steps:

[0113] Preparation of sulfide solid electrolyte layer

[0114] The sulfide solid electrolyte Li6PS5Cl and the binder are mixed at a mass ratio of 99.5:0.5 and dispersed in xylene solvent to form a slurry. The slurry is then coated and dried to form a sulfide solid electrolyte layer.

[0115] Preparation of the first hybrid layer

[0116] The first region is formed on both sides of the sulfide solid electrolyte layer by dotting.

[0117] On one side of the sulfide solid electrolyte layer, a halide solid electrolyte slurry is coated onto the remaining area of ​​the sulfide solid electrolyte layer surface, excluding the first area, ensuring that the first area is exposed, thus forming the first mixed layer.

[0118] Sulfide solid electrolyte is further dotted onto the first region to form a second region, and halide solid electrolyte slurry is coated onto the remaining regions except the second region to form a second layer of the first mixed layer.

[0119] Sulfide solid electrolyte is further dotted onto the second region to form a third region, and halide solid electrolyte slurry is coated onto the remaining regions except the third region to form a third layer of the first mixed layer.

[0120] Preparation of halide solid electrolyte layer

[0121] A halide solid electrolyte layer is formed by coating the surface of the third layer, the first mixed layer.

[0122] Preparation of the second hybrid layer

[0123] On the other side of the sulfide solid electrolyte layer, a first solid electrolyte slurry is coated on the remaining areas of the sulfide solid electrolyte layer surface except for the first region, ensuring that the sulfide solid electrolyte region is exposed, forming a first layer and a second mixed layer.

[0124] Sulfide solid electrolyte is further dotted onto the first region to form a second region, and the first solid electrolyte slurry is coated onto the remaining regions except the second region to form a second layer and a second mixed layer.

[0125] Sulfide solid electrolyte is further dotted onto the second region to form a third region. The first solid electrolyte slurry is then coated onto the remaining regions except the third region to form a third layer of the second mixed layer.

[0126] Preparation of the first solid electrolyte layer

[0127] A first solid electrolyte layer is formed by coating the surface of the third layer and the second mixed layer to obtain a composite solid electrolyte membrane.

[0128] The composite solid electrolyte membrane is densified by isostatic pressing.

[0129] The composite solid electrolyte membrane was placed in an isostatic pressing apparatus and subjected to densification processing at 400 MPa for 1 minute at 60°C.

[0130] This embodiment also provides a battery, including the above-mentioned composite solid electrolyte membrane, a positive electrode, and a negative electrode, wherein the positive electrode, the negative electrode, and the composite solid electrolyte membrane are stacked, and the composite solid electrolyte membrane is disposed between the positive electrode and the negative electrode.

[0131] The positive electrode includes the positive electrode active material LiNi. 0.8 Co 0.1 Mn 0.1 The composition of the product is as follows: O2, halide solid electrolyte Li3YCl6, conductive agent VGCF, and binder PTFE, with a mass ratio of 78:19.5:2:0.5.

[0132] When preparing the positive electrode, the positive electrode active material LiNi is used. 0.8 Co 0.1 Mn0.1 O2, halide solid electrolyte Li3YCl6, conductive agent VGCF, and binder PTFE are mixed in a mass ratio of 78:19.5:2:0.5, and then fiberized and rolled to obtain the positive electrode of a lithium-ion battery.

[0133] The negative electrode consists of graphite as the negative electrode active material, superconducting carbon black (SuperP) as the conductive agent, sodium carboxymethyl cellulose (CMC) as the binder, and styrene-butadiene rubber (SBR) as the binder, with a mass ratio of 96.5:1.0:1.0:1.5.

[0134] In preparing the negative electrode, graphite (the negative electrode active material), superconducting carbon black (SuperP) (the conductive agent), sodium carboxymethyl cellulose (CMC) (the binder), and styrene-butadiene rubber (SBR) (the binder) are mixed in a mass ratio of 96.5:1.0:1.0:1.5 to form a negative electrode slurry. This slurry is then coated onto copper foil (the current collector) and dried at 90°C to form a negative electrode active material layer. After cold pressing, edge trimming, and cutting, the negative electrode for lithium-ion batteries is obtained after slitting.

[0135] Example 2

[0136] Referring to Example 1, the difference from Example 1 is that both the first and second mixing layers are single layers, the thickness of the halide solid electrolyte layer is 10 μm, the thickness of the first mixing layer is 10 μm, the thickness of the sulfide solid electrolyte layer is 30 μm, the thickness of the second mixing layer is 10 μm, and the thickness of the first solid electrolyte layer is 10 μm. The mass ratio of sulfide solid electrolyte to halide solid electrolyte in the first mixing layer is 15:1 (from the halide electrolyte layer to the sulfide electrolyte layer), and the mass ratio of sulfide solid electrolyte to first solid electrolyte in the second mixing layer is 25:1 (from the sulfide electrolyte layer to the first solid electrolyte layer).

[0137] Example 3

[0138] Referring to Example 1, the difference from Example 1 is that the first and second mixed layers are both five layers, the thickness of the halide solid electrolyte layer is 10 μm, the thickness of the first mixed layer is 3 μm, the thickness of the sulfide solid electrolyte layer is 30 μm, the thickness of the second mixed layer is 3 μm, and the thickness of the first solid electrolyte layer is 10 μm.

[0139] In the direction from the halide solid electrolyte layer to the sulfide solid electrolyte layer, the mass ratios of sulfide solid electrolyte to halide solid electrolyte in the three first mixed layers are 8:1, 10:1, 15:1, 25:1, and 30:1, respectively.

[0140] In the direction from the sulfide solid electrolyte layer to the first solid electrolyte layer, the mass ratios of the sulfide solid electrolyte to the first solid electrolyte in the three second mixed layers are 49:1, 40:1, 30:1, 20:1, and 12:1, respectively.

[0141] Example 4

[0142] Referring to Example 1, the difference from Example 1 is that the first mixed layer has eight layers and the second mixed layer has seven layers, the thickness of the halide solid electrolyte layer is 10 μm, the thickness of the first mixed layer is 3 μm, the thickness of the sulfide solid electrolyte layer is 30 μm, the thickness of the second mixed layer is 3 μm, and the thickness of the first solid electrolyte layer is 10 μm.

[0143] In the direction from the halide solid electrolyte layer to the sulfide solid electrolyte layer, the mass ratios of sulfide solid electrolyte to halide solid electrolyte in the three first mixed layers are 1:1, 5:1, 10:1, 15:1, 20:1, 25:1, 29:1, and 34:1, respectively.

[0144] In the direction from the sulfide solid electrolyte layer to the first solid electrolyte layer, the mass ratios of the sulfide solid electrolyte to the first solid electrolyte in the three second mixed layers are 49:1, 38:1, 28:1, 21:1, 14:1, 8:1, and 1:1, respectively.

[0145] Comparative Example 1

[0146] The difference from Example 1 is that Example 1 only prepares the first solid electrolyte layer, without setting the first mixed layer, the second mixed layer, the halide solid electrolyte layer and the sulfide solid electrolyte layer.

[0147] Example 5

[0148] Referring to Example 1, the difference from Example 1 is that the halide solid electrolyte in the halide solid electrolyte layer and the first mixed layer is replaced with Li₂ZrCl₆, and the sulfide solid electrolyte in the sulfide solid electrolyte layer, the first mixed layer, and the second mixed layer is replaced with Li₂ZrCl₆. 10 GeP2S 11.7 O 0.3 In the first solid electrolyte layer and the second hybrid layer, the first solid electrolyte is replaced with LiCB9H. 10 .

[0149] Example 6

[0150] Referring to Example 1, the difference from Example 1 is that the thickness of the halide solid electrolyte layer is 20 μm, the thickness of the sulfide solid electrolyte layer is 20 μm, and the thickness of the first solid electrolyte layer is 10 μm.

[0151] Example 7

[0152] Referring to Example 1, the difference from Example 1 is that the thickness of the halide solid electrolyte layer is 10 μm, the thickness of the sulfide solid electrolyte layer is 40 μm, and the thickness of the first solid electrolyte layer is 10 μm.

[0153] Table 1

[0154]

[0155]

[0156] Table 2

[0157]

[0158] Performance testing

[0159] Cyclic performance test

[0160] ① Place the battery at room temperature of 25℃, charge it at 1C until the charging cutoff voltage is 4.25V and the cutoff current is 0.05C, and let it stand for 1 hour;

[0161] ② At room temperature of 25℃, discharge at a constant current of 1C until the discharge cutoff voltage is 3.0V, and let stand for 1 hour;

[0162] ③ Repeat steps ① to ② 200 times. Cyclic performance = discharge capacity on the 200th cycle / discharge capacity on the first cycle.

[0163] Ratio Performance Test

[0164] ① Place the battery at room temperature of 25℃, charge it with a charging current of 0.1C to the charging cutoff voltage of 4.25V, cutoff current of 0.05C, and let it stand for 1 hour; then discharge it with a constant current of 0.1C to the discharge cutoff voltage of 3.0V, and let it stand for 1 hour.

[0165] Record the battery's discharge capacity C0.

[0166] ② Place the battery at room temperature of 25℃, charge it at 1C to the charging cutoff voltage of 4.25V and the cutoff current of 0.05C, and let it stand for 1 hour; then discharge it at a constant current of 5C to the discharge cutoff voltage of 3.0V, and let it stand for 1 hour; record the discharge capacity C1 of the battery.

[0167] Rate performance (1C capacity retention rate) = C1 / C0 * 100%.

[0168] The cycle performance and 1C / 0.1C rate performance of the batteries prepared in Examples 1-7 and Example 1 were tested. The test results are shown in Table 3.

[0169] Table 3

[0170] 200cls capacity retention 1C / 0.1C rate performance Example 1 96.13％ 85.11％ Example 2 94.80％ 82.33％ Example 3 90.54％ 80.24％ Example 4 85.23％ 78.00％ Example 5 93.11％ 80.85％ Example 6 90.23％ 80.90％ Example 7 94.23％ 84.58％ Comparative Example 1 84.37％ 76.63％

[0171] The test results show that the capacity retention rate of Examples 1-8 of this invention remained above 90% for most of the 200 charge-discharge cycles, and the 1C / 0.1C rate performance was mostly above 80%. The comparison of the above experimental test data indicates that the composite solid electrolyte proposed in this invention achieves a synergistic effect of "high voltage resistance on the positive electrode side and reduction resistance on the negative electrode side," while also maintaining high overall ionic conductivity. This improves the electrochemical stability and ionic conductivity of the composite solid electrolyte membrane, thereby enhancing battery cycle performance and rate performance.

[0172] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A composite solid electrolyte membrane, characterized in that, It includes a halide solid electrolyte layer, a first solid electrolyte layer, and a sulfide solid electrolyte layer disposed between the halide solid electrolyte layer and the first solid electrolyte layer. The first solid electrolyte layer includes a first solid electrolyte, which includes a borohydride solid electrolyte and / or a carborohydride solid electrolyte.

2. The composite solid electrolyte membrane as described in claim 1, characterized in that, The thickness ratio of the halide solid electrolyte layer to the sulfide solid electrolyte layer is 1:1 to 1:12; And / or, the thickness ratio of the first solid electrolyte layer to the sulfide solid electrolyte layer is 1:1 to 1:

12.

3. The composite solid electrolyte membrane as described in claim 2, characterized in that, The composite solid electrolyte membrane further includes a first mixing layer disposed between the halide solid electrolyte layer and the sulfide solid electrolyte layer, the first mixing layer comprising halide solid electrolyte and sulfide solid electrolyte.

4. The composite solid electrolyte membrane as described in claim 2, characterized in that, The composite solid electrolyte membrane further includes a second mixing layer disposed between the sulfide solid electrolyte layer and the first solid electrolyte layer, the second mixing layer comprising the first solid electrolyte and the sulfide solid electrolyte.

5. The composite solid electrolyte membrane as described in claim 4, characterized in that, The first mixing layer has a multi-layer structure. In each layer of the first mixing layer, the mass ratio w1 of halide solid electrolyte to sulfide solid electrolyte satisfies: w1 = 1:34 to 1:

1.

6. The composite solid electrolyte membrane as described in claim 5, characterized in that, In the direction from the halide solid electrolyte layer to the sulfide solid electrolyte layer, in adjacent first mixed layers, the mass percentage of the halide solid electrolyte decreases, and the mass percentage of the sulfide solid electrolyte increases.

7. The composite solid electrolyte membrane as described in claim 4, characterized in that, The second mixing layer has a multi-layer structure. In each layer of the second mixing layer, the mass ratio w2 of the first solid electrolyte to the sulfide solid electrolyte satisfies: w2 = 1:49 to 1:

1.

8. The composite solid electrolyte membrane as described in claim 7, characterized in that, In the direction from the first solid electrolyte layer to the sulfide solid electrolyte layer, in the adjacent second mixed layer, the mass percentage of the first solid electrolyte decreases, and the mass percentage of the sulfide solid electrolyte increases.

9. A method for preparing a composite solid electrolyte membrane as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Preparation of sulfide solid electrolyte layer; S2. Prepare the halide solid electrolyte layer on one side of the sulfide solid electrolyte layer or prepare the first mixed layer and the halide solid electrolyte layer in sequence. S3. Prepare a first solid electrolyte layer on the other side of the sulfide solid electrolyte layer or prepare a second mixed layer and a first solid electrolyte layer in sequence to obtain a composite solid electrolyte membrane.

10. A lithium battery, characterized in that, The device includes a composite solid electrolyte membrane as described in any one of claims 1 to 8, a positive electrode, and a negative electrode, wherein the positive electrode, the negative electrode, and the composite solid electrolyte membrane are stacked, and the composite solid electrolyte membrane is disposed between the positive electrode and the negative electrode; and the halide solid electrolyte layer is disposed close to the positive electrode, and the first solid electrolyte layer is disposed close to the negative electrode.

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