Self-repairing composite solid electrolyte membrane and preparation method thereof and electrochemical device

Abstract

The present invention provides a self-repairing composite solid electrolyte membrane, a preparation method thereof, and an electrochemical device. The composite solid electrolyte membrane comprises a three-dimensional porous framework of a sulfide solid electrolyte, a polymer filler, a lithium salt, and an initiator; the polymer filler comprises any one of a polymaleic acid diamine filler, a poly-2-methylmaleic acid diamine filler, a poly-2-ethylmaleic acid diamine filler, a poly-N-methylmaleic acid diamine filler, or a poly-N-ethylmaleic acid diamine filler, or a combination of at least two thereof. The present invention uses a sulfide solid electrolyte as a three-dimensional porous framework, introduces a monomer dissolving and re-casting method into the framework structure, and the monomer forms a polymer filler through polymerization. The polymer filler can adhere to the surface of the electrolyte particles, thereby making hydrogen bonding more likely to occur, thereby achieving the purpose of self-repair.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrolyte materials, and in particular relates to a self-repairing composite solid electrolyte membrane, a preparation method thereof, and an electrochemical device. Background Art

[0002] As a secondary battery, lithium-ion battery works on the principle that lithium ions move between the positive electrode and the negative electrode to realize the charging and discharging process. + Insertion and deinsertion back and forth between the two electrodes: During the charging process, Li + Lithium is released from the positive electrode and then embedded in the negative electrode through the electrolyte, leaving the negative electrode in a lithium-rich state. The discharge process is the opposite. Lithium-ion batteries have become widely used due to their high energy density, lack of memory effect, high operating voltage, and environmental friendliness. With the growing demand for electronic products and the rapid development of power and energy storage devices, power lithium batteries are finding applications in power tools and electric vehicles, placing increasing demands on their performance.

[0003] As one of the most important electrochemical energy storage devices currently, the application scope of lithium-ion batteries has gradually expanded from the use of small-capacity batteries in consumer electronics and power tools to emerging fields such as new energy electric vehicles, electric ships, electric aircraft and robots. These fields not only require lithium-ion batteries to have higher capacity, but also continuously put forward higher requirements for their energy density.

[0004] In the past, the energy density of lithium-ion batteries increased over time in a generally linear manner, but in recent years, the rate of increase in energy density has gradually slowed down. At the same time, liquid batteries have the following drawbacks:

[0005] (1) SEI layer continues to grow

[0006] Since the SEI layer is not dense and the positive and negative electrode materials have large volume expansion and contraction during the cycle, some components in the SEI layer will dissolve in the electrolyte, causing the SEI layer on the positive and negative electrode surfaces to continue to grow, resulting in a decrease in active lithium and continuous depletion of the electrolyte. The internal resistance and internal pressure of the battery continue to increase, and the volume of the electrodes continues to expand.

[0007] (2) Transition metal dissolution

[0008] For layered and spinel oxide cathode materials, the cathode is in a high oxidation state when charged and is prone to reduction phase transition. The transition metal ions in the skeleton interact with the solvent in the electrolyte and precipitate into the electrolyte and diffuse to the negative electrode, catalyzing the further growth of the SEI layer. At the same time, the surface structure of the cathode material is destroyed, the internal resistance of the battery increases, and the reversible capacity continues to lose. Due to the role of transition metals in catalyzing the growth of the SEI layer, the battery's requirement for free magnetic metals in all materials reaches tens of ppb (1 ppb = 1 × 10 -9 ) level, which also leads to an increase in battery material costs;

[0009] (3) Oxygen evolution from cathode materials

[0010] For high-capacity layered oxides, when charged to a higher voltage, the oxygen atoms in the positive electrode lattice easily lose electrons and precipitate from the lattice in the form of free oxygen, which then undergoes an oxidation reaction with the electrolyte, causing the structure of the positive electrode material to gradually destroy the thermal runaway of the battery, and at the same time, triggering thermal runaway of the battery;

[0011] (4) Electrolyte oxidation

[0012] In order to increase the capacity of the positive electrode material, it needs to be charged to a high voltage to release more lithium. Currently, the electrolyte solution for lithium cobalt oxide can be charged to 4.45V, and the ternary material can be charged to 4.35V. If the voltage is further increased, the electrolyte will undergo oxidative decomposition and the surface of the positive electrode will undergo an irreversible phase change.

[0013] (5) Lithium precipitation

[0014] Due to the slow kinetics of embedding lithium into the negative electrode material, under low-temperature overcharging or high-current charging, metallic lithium is directly deposited on the negative electrode surface, which may cause lithium dendrites and cause a micro-short circuit in the battery. The highly active metallic lithium directly undergoes a reduction reaction with the liquid electrolyte, resulting in the loss of active lithium and an increase in the internal resistance of the battery.

[0015] (6) High temperature failure

[0016] When the battery is fully charged, the negative electrode is in a reduced state and the positive electrode is in a highly oxidized state. At high temperatures, the solubility of some components in the SEI layer increases, causing the highly active positive and negative electrode materials to react with the electrolyte. At the same time, lithium salts will also spontaneously decompose at high temperatures and catalyze electrolyte reactions. These reactions may cause thermal runaway of the battery.

[0017] (7) Volume expansion

[0018] After adopting a high-capacity silicon negative electrode, after high-temperature expansion or long-term circulation, the volume expansion of the soft-pack battery cell exceeds 10% of the application requirements due to the continuous decomposition of the electrolyte, SEI growth and reaction gas production, and large changes in the volume of the negative electrode itself.

[0019] In summary, the aforementioned shortcomings of liquid batteries are related to the electrolyte's low chemical, electrochemical, and thermal stability. To improve battery safety, methods such as adding flame-retardant additives to liquid electrolytes or employing ionic liquids have been extensively researched and developed. However, considering the need to optimize the overall performance of battery cells, these approaches cannot simultaneously address these shortcomings. In recent years, solid-state electrolytes have become a key research direction.

[0020] However, the interface contact of all-solid-state lithium batteries is mainly solid-solid interface contact, so ensuring good interface contact is the key to ensuring battery performance. However, as the positive and negative electrode materials undergo large deformation, the volume change of the electrode material can easily cause the electrolyte layer to break, leading to short circuit and thermal runaway in the positive and negative electrode contact.

[0021] Therefore, in the art, it is desired to develop a solid electrolyte that not only has high ionic conductivity but also has good structural stability, avoids cracking of the electrolyte, and has good interface contact performance with the electrode material. Summary of the Invention

[0022] To address the shortcomings of the existing technology, the present invention aims to provide a self-healing composite solid electrolyte membrane, its preparation method, and electrochemical device. This invention utilizes a sulfide solid electrolyte as a three-dimensional porous framework. By dissolving and then recasting monomers into the framework, the monomers polymerize to form a polymer filler, which adheres to the surface of the electrolyte particles, facilitating hydrogen bonding and achieving self-healing properties.

[0023] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0024] In a first aspect, the present invention provides a self-repairing composite solid electrolyte membrane, comprising a sulfide solid electrolyte three-dimensional porous skeleton, a polymer filler, a lithium salt, and an initiator;

[0025] The polymer filler includes any one of polymaleic acid diamine filler, poly 2-methylmaleic acid diamine filler, poly 2-ethylmaleic acid diamine filler, poly N-methylmaleic acid diamine filler or poly N-ethylmaleic acid diamine filler, or a combination of at least two thereof.

[0026] The present invention uses a sulfide solid electrolyte with high grain boundary conductivity as a three-dimensional porous framework. By dissolving and then recasting monomers into the framework structure, the monomers form polymers through free radical polymerization. The polymers then self-repair through hydrogen bonding, thereby eliminating the risk of cracking in the electrolyte layer. Simultaneously, the polymers can bind to lithium ions through complexation, thereby improving the conductivity of the electrolyte layer. Furthermore, the polymers can adhere to the surface of the electrolyte particles, making hydrogen bonding more likely to occur, thus achieving the purpose of self-repair.

[0027] Preferably, the mass ratio of the sulfide solid electrolyte three-dimensional porous skeleton, polymer filler, lithium salt and initiator in the composite solid electrolyte membrane is (40 to 90): (4.9 to 49): (5 to 10): (0.1 to 1), for example, it can be 40:49:10:1, 50:41:8:1, 60:30:9:1, 70:20:9.5:0.5, 90:4.9:5:0.1. For the sake of space, the point values ​​listed in the above range are no longer listed one by one.

[0028] In the present invention, by regulating the mass ratio of the sulfide solid electrolyte three-dimensional porous skeleton, polymer filler, lithium salt and initiator in the composite solid electrolyte membrane, if the mass ratio of the sulfide solid electrolyte three-dimensional porous skeleton is too high and the mass ratio of the polymer filler is too low, the prepared electrolyte membrane cannot have the self-repair function; if the mass ratio of the sulfide solid electrolyte three-dimensional porous skeleton is too low and the mass ratio of the polymer is too high, the conductivity of the prepared electrolyte membrane is low.

[0029] Preferably, the three-dimensional porous framework of the sulfide solid electrolyte is selected from Li6PS5Cl, Li2S-GeS2, Li2S-SiS2, (100-x)Li2S-xP2S5, Li2S-MS2-P2S5, Li2S-MS y -At least one of LiX, thio-LISICON, Li2S-SnS2-P2S5, Li2S-Al2S3-P2S5 or Li-Argyrodite, wherein the value range of x is 0≤x≤100, M is selected from any one of Si, Ge, Sn or P, X is selected from any one of halogen atoms, and the value range of y is 0≤y≤5, or a sulfide electrolyte system in which the above systems are doped and modified.

[0030] As a preferred technical solution of the present invention, the three-dimensional porous framework of the sulfide solid electrolyte is selected from 80Li2S-20P2S5, 75Li2S-25P2S5 and related phases, 70Li2S-30P2S5 and related phases, Li7P2S8I, Li7P2S8Br 0.5 I 0.5 、Li3.25 Ge 0.25 P 0.75 S4, Li 10 GeP2S 12 、Li 11 Si2PS 12 、Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 、Li6PS5Cl、Li 5.5 PS 4.5 Cl 1.5 or Li 6.6 P 0.4 Ge 0.6 Any of S5I.

[0031] Preferably, the porosity of the sulfide solid electrolyte three-dimensional porous skeleton is 30% to 50%, for example, it can be 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, or 50%.

[0032] In the present invention, the porosity of the three-dimensional porous skeleton of the sulfide solid electrolyte is adjusted so that it has good ionic conductivity, thereby promoting the rapid transmission of lithium ions.

[0033] In the present invention, the lithium salt includes at least one of lithium nitrate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(perfluorobutylsulfonyl)imide, lithium (trifluoromethylsulfonyl)(perfluorobutylsulfonyl)imide, lithium (fluorosulfonyl)(perfluorobutylsulfonyl)imide or lithium bis(oxalatoborate).

[0034] In the present invention, the initiator includes azobisisobutyronitrile.

[0035] In a second aspect, the present invention provides a method for preparing the self-repairing composite solid electrolyte membrane according to the first aspect, the method comprising the following steps:

[0036] (1) mixing a sulfide solid electrolyte, a pore-forming agent, and a solvent to obtain a slurry, and then drying and rolling the slurry to obtain a three-dimensional porous framework of a sulfide solid electrolyte;

[0037] (2) mixing the monomer, lithium salt and organic solvent, and adding an initiator to obtain a monomer solution;

[0038] (3) pouring the monomer solution onto the surface of the three-dimensional porous skeleton of the sulfide solid electrolyte, performing polymerization and hot pressing to obtain the self-repairing composite solid electrolyte membrane.

[0039] Preferably, the pore-forming agent in step (1) is selenium disulfide or arsenic sulfide.

[0040] In the present invention, selenium disulfide or arsenic sulfide pore-forming agents are added to prepare a high-porosity three-dimensional porous skeleton of a sulfide solid electrolyte. Since selenium disulfide is solid at room temperature and decomposes at 118°C, its volatilization temperature is relatively low. Moreover, as a sulfide, it will not undergo side reactions with the sulfide electrolyte at high temperatures.

[0041] Preferably, the content of the pore-forming agent in step (1) is 1% to 10%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%.

[0042] In the present invention, the content of the pore-forming agent in step (1) is adjusted so that the three-dimensional porous skeleton of the sulfide solid electrolyte has an appropriate porosity.

[0043] In the present invention, the solvent in step (1) is dimethyl carbonate.

[0044] In the present invention, the mixing in step (1) is performed under stirring.

[0045] Preferably, the solid content of the slurry in step (1) is 50% to 60%, for example, it can be 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, or 60%.

[0046] In the present invention, the solid content of the slurry in step (1) is adjusted so that it is easy to process and has an appropriate content. If the solid content is too low, the quality of the three-dimensional porous skeleton of the sulfide solid electrolyte will be too low to function. Otherwise, the slurry will become viscous and difficult to handle.

[0047] In the present invention, the drying in step (1) is vacuum drying.

[0048] In the present invention, the thickness of the rolling in step (1) is 5 μm to 100 μm, for example, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm.

[0049] In the present invention, by controlling the thickness of the rolling process, the self-repairing composite solid electrolyte membrane has the advantages of being light and thin and having low impedance.

[0050] In the present invention, the rolling process in step (1) also includes a vacuum drying process.

[0051] In the present invention, the temperature of the vacuum drying process is 130°C to 200°C, for example, 130°C, 150°C, 180°C, or 200°C.

[0052] In the present invention, the organic solvent in step (2) is ethanol.

[0053] Preferably, the solid content of the monomer solution in step (2) is 1% to 30%, for example, it can be 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, or 30%.

[0054] In the present invention, the composite solid electrolyte membrane has a good composite effect by controlling the solid content of the monomer solution.

[0055] Preferably, the polymerization temperature in step (3) is 40°C to 80°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C.

[0056] Preferably, the polymerization time in step (3) is 6 h to 48 h, for example, 6 h, 12 h, 24 h, 36 h, or 48 h.

[0057] Preferably, the hot pressing in step (3) is isothermal static hot pressing.

[0058] Preferably, the hot pressing pressure in step (3) is 100 MPa to 1000 MPa, for example, it can be 100 MPa, 200 MPa, 300 MPa, 400 MPa, 450 MPa, 500 MPa, 600 MPa, 800 MPa, or 1000 MPa.

[0059] Preferably, the temperature of the hot pressing in step (3) is 30°C to 120°C, for example, 30°C, 50°C, 60°C, 85°C, 105°C, or 120°C.

[0060] In a third aspect, the present invention provides an electrochemical device comprising a positive electrode sheet, a negative electrode sheet, and a solid electrolyte, wherein the solid electrolyte comprises the self-repairing composite solid electrolyte membrane according to the first aspect.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] The present invention provides a self-healing composite solid electrolyte membrane. Using a sulfide solid electrolyte with high grain boundary conductivity as a three-dimensional porous framework, the membrane is introduced into the framework structure by dissolving and then recasting monomers. The monomers form polymers through free radical polymerization, and the polymers self-heal through hydrogen bonding, thereby eliminating the risk of cracking in the electrolyte layer. Simultaneously, the polymers can bind to lithium ions through complexation, thereby improving the conductivity of the electrolyte layer. Furthermore, the polymers can adhere to the surface of the electrolyte particles, making hydrogen bonding more likely to occur, achieving the purpose of self-healing.

[0063] In the preparation method provided by the present invention, selenium disulfide or arsenic sulfide is further preferably used as a pore-forming agent, which has the advantages of volatilization at low temperature and no side reaction with the sulfide solid electrolyte. DETAILED DESCRIPTION

[0064] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0065] Example 1

[0066] This embodiment provides a self-healing composite solid electrolyte membrane, comprising a three-dimensional porous framework of a Li6PS5Cl sulfide solid electrolyte (porosity 13%), a poly(maleic acid diamine) filler, LiTFSI, and an azobisisobutyronitrile initiator. The mass ratio of the three-dimensional porous framework of the Li6PS5Cl sulfide solid electrolyte, the poly(maleic acid diamine) filler, the lithium salt, and the initiator in the composite solid electrolyte membrane is 85:9.9:5:0.1.

[0067] The preparation method of the self-repairing composite solid electrolyte membrane is as follows:

[0068] (1) The sulfide solid electrolyte, selenium disulfide pore former and dimethyl carbonate were degassed and stirred at 2000 rpm for 10 minutes, and then degassed and stirred at 500 rpm for 5 minutes to obtain a slurry with a solid content of 50%. The slurry was then evenly coated on aluminum foil with a coating gap of 100 μm, vacuum dried and rolled to a thickness of about 50 μm; and then vacuum dried at 150°C to obtain a three-dimensional porous skeleton of the sulfide solid electrolyte.

[0069] (2) mixing maleic acid diamine, LiTFSI, and ethanol, and adding 0.1% by mass of azobisisobutyronitrile as an initiator to obtain a maleic acid diamine solution having a solid content of 20%;

[0070] (3) The maleic acid diamine solution is poured on the surface of the three-dimensional porous skeleton of the sulfide solid electrolyte, polymerized at 60°C for 24 hours, and then vacuum dried at 100°C for 12 hours to ensure that the ethanol in the electrolyte layer has been completely removed. The isostatic hot pressing treatment is performed, wherein the static pressing pressure is 450 MPa, the time is 2 hours, and the temperature is 85°C to obtain the self-repairing composite solid electrolyte membrane.

[0071] This embodiment also provides a lithium ion battery, and the preparation method of the lithium ion battery is as follows:

[0072] The preparation process of the positive electrode sheet is completed entirely under -70℃ dew point conditions or in a glove box. Before the experimental operation, the positive electrode material must first be dehydrated to ensure that the water content of the material is ≤10ppm.

[0073] 1. Preparation of conductive adhesive: 30g of polyvinylidene fluoride material and an appropriate amount of anisole solvent are heated and stirred to dissolve to form an adhesive with a solid content of 7%. Then, 50g of vapor-grown carbon nanofiber material is added to form a conductive adhesive;

[0074] 2. Preparation of positive electrode slurry: 700g NCM 622 powder and 220g Li6PS5Cl electrolyte were added to a deaerator and dry-mixed for 15 minutes. The mixture was then added to the conductive adhesive solution with a solid content of 75%. The mixture was centrifuged for 20 minutes and deaerated for 5 minutes to prepare the positive electrode slurry.

[0075] 3. The electrode is coated on the aluminum foil by doctor blade coating with a gap of 80 to 90 microns. After coating, the solvent is naturally dried, and then transferred to a vacuum drying oven and vacuum dried at 120 ° C for 12 hours. After that, the positive electrode is obtained by roller pressing. The active material loading is 15 mg / cm 2 , thickness is 43μm;

[0076] The preparation process of the negative electrode sheet is completed entirely under -70℃ dew point conditions or in a glove box. Before the experimental operation, the negative electrode material must first be dehydrated to ensure that the water content of the material is ≤10ppm.

[0077] 4. Preparation of conductive adhesive: 30g of polyvinylidene fluoride material and an appropriate amount of anisole solvent are heated and stirred to dissolve to form an adhesive with a solid content of 7%. Then, 50g of vapor-grown carbon nanofiber material is added to form a conductive adhesive;

[0078] 5. Preparation of negative electrode slurry: 70g silicon carbon powder (650mAh / g) and 2.2g Li6PS5Cl electrolyte were added to a degassing mixer and dry-mixed for 15 minutes. The mixture was then added to the conductive adhesive solution with a solid content of 50%. The mixture was centrifuged for 20 minutes and degassed for 5 minutes to prepare the negative electrode slurry.

[0079] 6. The electrode was coated on the aluminum foil by doctor blade coating with a gap of 80 to 90 μm. After coating, the solvent was allowed to dry naturally, and then transferred to a vacuum drying oven and vacuum dried at 120 ° C for 12 hours. After that, the negative electrode was obtained by roller pressing. The active material loading was 4.1 mg / cm 2 , thickness is 30 μm;

[0080] Preparation of lithium-ion batteries: The positive and negative electrodes are cut to a certain size, and then assembled into a soft-pack battery in a stacking manner of 4 positive and 5 negative. The capacity of the soft-pack battery is about 500mAh. A mold is installed on the outside and an external pressure of about 1Mpa is applied.

[0081] Other examples and comparative examples are based on the steps of Example 1 with parameter changes. The specific changed parameters are shown in Table 1:

[0082] Table 1

[0083]

[0084]

[0085] Test conditions

[0086] The self-repairing composite solid electrolyte membranes provided in Examples 1 to 14 and Comparative Examples 1 to 2 were tested for ionic conductivity, electronic conductivity, porosity, electrochemical window, and self-repair time, respectively. The test methods are as follows:

[0087] (1) Room temperature ionic conductivity test

[0088] The prepared self-healing composite solid electrolyte membrane was punched out in a glove box and the conductivity was tested using a mold cell. The test conditions were: diameter 10 mm, test pressure 50 MPa, room temperature 23±2°C, and the test was performed using a Bio-logic MTZ-35 impedance analyzer with a frequency of 3.5 MHz to 0.1 Hz.

[0089] (2) DC polarization electronic conductivity test

[0090] In a glove box, at 25°C, use a mold battery, apply 50 MPa pressure, use blocking electrodes at both ends (electron conduction, ion blocking), sandwich a self-repairing composite solid electrolyte membrane in the middle, and start applying a constant voltage of 0.5V DC polarization for 3000s. Record the current after 3000s of DC. Electronic resistance = constant voltage / DC current. Then calculate the electronic conductivity using the conductivity test formula;

[0091] (3) Porosity calculation

[0092] The porosity of the electrolyte layer can be calculated by the true density of Li6PS5Cl, PVP, PEI, the thickness and mass of the electrolyte layer;

[0093] (4) Electrochemical window test of electrolyte layer

[0094] At 25°C, a Li|self-healing composite solid electrolyte membrane|SUS button cell was assembled in a glove box. One side contained a stainless steel sheet, a lithium-ion blocking electrode; the other side contained a lithium-ion reversible electrode, a lithium-copper composite ribbon; and the center contained a sulfide solid electrolyte layer. Cyclic voltammetry scans were performed from the open circuit voltage to -0.5V, then from -0.5V to 10V, repeating this cycle at a scan rate of 0.5mV / s to determine the cell's initial oxidation current.

[0095] (5) Self-repair time

[0096] A 5 cm long incision was cut in the electrolyte layer with a knife, and then the incision was bonded together to confirm the time required for the incision to be completely healed.

[0097] The test results are shown in Table 2:

[0098] Table 2:

[0099]

[0100] It can be seen from the data in Tables 1 and 2 that, through the examples and comparative examples, it can be determined that if too much sulfide electrolyte material is added, although the ionic conductivity of the electrolyte layer is high, it does not have self-healing properties. If more pore-forming agent is added, more self-healing electrolyte can be added and the self-healing time is faster, but the ionic conductivity of the electrolyte layer will be affected.

[0101] The applicant states that while the above-described embodiments illustrate the process of the present invention, the present invention is not limited to the above-described process steps, nor does it imply that the present invention must rely on the above-described process steps for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A self-repairing composite solid electrolyte membrane, characterized in that: The composite solid electrolyte membrane includes a sulfide solid electrolyte three-dimensional porous skeleton, a polymer filler, a lithium salt and an initiator; The polymer filler includes any one of polymaleic acid diamine filler, poly 2-methylmaleic acid diamine filler, poly 2-ethylmaleic acid diamine filler, poly N-methylmaleic acid diamine filler or poly N-ethylmaleic acid diamine filler, or a combination of at least two thereof.

2. The composite solid electrolyte membrane according to claim 1, characterized in that The mass ratio of the sulfide solid electrolyte three-dimensional porous skeleton, polymer filler, lithium salt and initiator in the composite solid electrolyte membrane is (40 to 90): (4.9 to 49): (5 to 10): (0.1 to 1).

3. The composite solid electrolyte membrane according to claim 1 or 2, characterized in that The three-dimensional porous framework of the sulfide solid electrolyte is selected from Li6PS5Cl, Li2S-GeS2, Li2S-SiS2, (100-x)Li2S-xP2S5, Li2S-MS2-P2S5, Li2S-MS y -At least one of LiX, thio-LISICON, Li2S-SnS2-P2S5, Li2S-Al2S3-P2S5 or Li-Argyrodite, wherein the value range of x is 0≤x≤100, M is selected from any one of Si, Ge, Sn or P, X is selected from any one of halogen atoms, and the value range of y is 0≤y≤5, or a sulfide electrolyte system modified by doping the above systems; The porosity of the three-dimensional porous skeleton of the sulfide solid electrolyte is 30% to 50%.

4. A method for preparing a self-repairing composite solid electrolyte membrane according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: (1) mixing a sulfide solid electrolyte, a pore-forming agent, and a solvent to obtain a slurry, and then drying and rolling the slurry to obtain a three-dimensional porous framework of a sulfide solid electrolyte; (2) mixing the monomer, lithium salt and organic solvent, and adding an initiator to obtain a monomer solution; (3) pouring the monomer solution onto the surface of the three-dimensional porous skeleton of the sulfide solid electrolyte, performing polymerization and hot pressing to obtain the self-repairing composite solid electrolyte membrane.

5. The method according to claim 4, characterized in that The pore-forming agent in step (1) is selenium disulfide or arsenic sulfide; The content of the pore-forming agent in step (1) is 1% to 10%.

6. The method according to claim 4, characterized in that The solid content of the slurry in step (1) is 50% to 60%.

7. The method according to claim 4, characterized in that The solid content of the monomer solution in step (2) is 1% to 30%.

8. The method according to claim 4, characterized in that The polymerization temperature in step (3) is 40° C. to 80° C.; The polymerization time in step (3) is 6 hours to 48 hours.

9. The method according to claim 4, characterized in that The hot pressing in step (3) is isothermal static hot pressing; The hot pressing pressure in step (3) is 100 MPa to 1000 MPa; The temperature of the hot pressing in step (3) is 30°C to 120°C.

10. An electrochemical device, characterized in that The electrochemical device comprises a positive electrode sheet, a negative electrode sheet and a solid electrolyte, wherein the solid electrolyte comprises the self-repairing composite solid electrolyte membrane according to any one of claims 1 to 3.

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