A composite binder, a preparation method thereof, and application in a negative electrode of an all-solid-state lithium-ion battery

Abstract

The present invention discloses a composite binder, a preparation method thereof, and its application in the negative electrode of an all-solid-state lithium-ion battery, relating to the technical field of all-solid-state lithium batteries. The invention comprises the following steps: ion-exchange and lithiation of sodium styrene sulfonate followed by copolymerization with isoprene to obtain a binder having both ion conduction and elastic buffering functions; the binder is then compounded with PMMA in a butyl butyrate / toluene mixed solvent to form a sulfide-compatible composite binder solution; the binder is then mixed with a silicon-based material, a Li6PS5Cl electrolyte, and a conductive agent in an optimized ratio to form a slurry; and after coating, step drying, and cold pressing, a high-performance composite negative electrode is obtained. This invention effectively solves the problems of sulfide electrolyte decomposition, silicon volume expansion, and high interfacial impedance in traditional systems, thereby improving the cycle stability and rate performance of sulfide all-solid-state lithium batteries. Furthermore, the process is compatible with existing production lines, providing significant industrial advantages.

Description

Technical Field

[0001] The present invention relates to the technical field of all-solid-state lithium batteries, and in particular to a composite binder, a preparation method thereof, and application in the negative electrode of an all-solid-state lithium-ion battery. Background Art

[0002] With the growing demand for high-energy-density batteries in new energy vehicles, sulfide all-solid-state batteries have attracted much attention due to their theoretical energy density exceeding 300Wh / kg and inherent safety. However, there are many technical bottlenecks in the wet-process preparation of silicon-based composite anodes, especially the interfacial compatibility between the silicon-based composite anode and the sulfide electrolyte:

[0003] First, sulfide solid electrolytes are extremely sensitive to conventional polar solvents (NMP, DMF, etc.). Upon contact, they undergo irreversible chemical decomposition reactions, producing not only toxic gases such as H2S but also the formation of an insulating layer at the interface, causing the ionic conductivity to drop by more than two orders of magnitude, directly damaging the electrochemical performance of the battery.

[0004] Secondly, traditional binder systems (such as PVDF, PAA, CMC, etc.) have poor solubility and dispersibility in low-polarity solvents, making it difficult to form a uniform and stable slurry. Cracks and holes are easily formed after film formation, seriously affecting the integrity of the electrode structure.

[0005] Furthermore, the volume change of silicon materials during charge and discharge, which can reach up to 300%, will destroy the close contact between the electrode and the electrolyte interface, causing the continuous growth of the interfacial impedance. Polymethyl methacrylate (PMMA), as a conventional binder for silicon anodes, has a certain inhibitory effect on the volume expansion of silicon. However, its film-forming rigidity is too strong and its toughness is insufficient. When used alone, it is easy to cause cracking of the electrode structure due to silicon expansion.

[0006] In addition, the core contradiction of the existing binder system is that traditional binders cannot simultaneously meet the four key requirements of chemical compatibility with sulfide electrolytes, buffering adaptability to silicon volume expansion, sufficient mechanical support strength and ion conductivity.

[0007] These problems have seriously restricted the performance improvement and industrialization process of sulfide all-solid-state batteries, and there is an urgent need to develop a new solvent-binder synergistic system to break through these technical barriers. Summary of the Invention

[0008] In view of this, the object of the present invention is to provide a composite binder and a preparation method thereof and application in the negative electrode of an all-solid-state lithium-ion battery.

[0009] The object of the present invention is achieved through the following technical solutions:

[0010] <First Aspect>

[0011] The present invention provides a method for preparing a composite binder solution, comprising the following steps:

[0012] Lithium styrene sulfonate-isoprene copolymer and polymethyl methacrylate are added into a mixed solvent of butyl butyrate and toluene, and the mixture is blended to obtain the composite binder solution.

[0013] As an embodiment, the mass ratio of lithium styrene sulfonate-isoprene copolymer to polymethyl methacrylate is 9~21:9.

[0014] In some embodiments, the mass ratio of lithium styrene sulfonate-isoprene copolymer to polymethyl methacrylate is 11-13.5:9.

[0015] As an embodiment, the mass ratio of butyl butyrate to toluene in the mixed solvent is 0.5~2:1.

[0016] In some embodiments, the mass ratio of butyl butyrate to toluene in the mixed solvent is 1:1.

[0017] As an embodiment, the solid content of the composite binder solution is 4-8 wt.%.

[0018] In some embodiments, the composite binder solution has a solid content of 5 wt.%.

[0019] As an embodiment, the blending is carried out at a temperature of 40-80°C.

[0020] In some embodiments, the blending is performed at 50°C.

[0021] As an embodiment, the preparation method of the lithium styrene sulfonate-isoprene copolymer is as follows: under a protective atmosphere, lithium styrene sulfonate and isoprene are dissolved in anhydrous toluene, an initiator is added, and a thermally initiated free radical copolymerization reaction is carried out, and the lithium styrene sulfonate-isoprene copolymer is obtained after vacuum drying.

[0022] As an embodiment, the initiator is selected from one or more of AIBN, benzoyl peroxide (BPO), dicumyl peroxide (DCP), and azobis(2-isoheptanonitrile) (ABVN).

[0023] In some embodiments, the initiator is AIBN.

[0024] As an embodiment, the molar ratio of lithium styrene sulfonate to isoprene is 1:1-3.

[0025] As an embodiment, the mass ratio of lithium styrene sulfonate to isoprene is 0.93~2.80:1.

[0026] In some embodiments, the mass ratio of lithium styrene sulfonate to isoprene is 1.35-1.80:1.

[0027] As an embodiment, the amount of the initiator is 0.5-1.5 wt.% of the mass of lithium styrene sulfonate.

[0028] In some embodiments, the amount of the initiator used is 1.2 wt.% or 1.5 wt.% of the mass of lithium styrene sulfonate.

[0029] As an embodiment, the ratio of lithium styrene sulfonate to anhydrous toluene is 1g: 5-15g.

[0030] In some embodiments, the ratio of lithium styrene sulfonate to anhydrous toluene is 1 g:10 g.

[0031] In some embodiments, the temperature of the free radical copolymerization reaction is 60-80° C., and the reaction time is 8-12 hours.

[0032] In some embodiments, the temperature of the free radical copolymerization reaction is 65-70° C., and the reaction time is 10-12 h.

[0033] As an embodiment, the preparation method of the lithium styrene sulfonate is: using a lithium hydroxide aqueous solution to neutralize a styrene sulfonic acid aqueous solution to neutralize it, and extracting the product to obtain the lithium styrene sulfonate.

[0034] As an embodiment, the concentration of the lithium hydroxide aqueous solution is 5-10 wt.%.

[0035] In some embodiments, the concentration of the lithium hydroxide aqueous solution is 8-10 wt.%.

[0036] As an embodiment, the preparation method of the styrenesulfonic acid aqueous solution is: passing the sodium styrenesulfonate aqueous solution through a hydrogen-type strongly acidic cation exchange resin column for ion exchange to obtain the styrenesulfonic acid aqueous solution.

[0037] As an embodiment, the concentration of the styrenesulfonic acid aqueous solution is 0.001~0.05g / mL.

[0038] In some embodiments, the concentration of the styrenesulfonic acid aqueous solution is 0.01 g / mL.

[0039] As an embodiment, the vacuum degree of the vacuum drying is 0.03-0.08 MPa, the temperature is 40-80° C., and the time is 10-15 h.

[0040] <Second Aspect>

[0041] The present invention provides an adhesive prepared by adopting the above method.

[0042] <Third Aspect>

[0043] The present invention provides a method for preparing a negative electrode sheet using the composite binder solution, comprising the following steps:

[0044] Nano-silicon particles, Li6PS5Cl electrolyte, conductive carbon VGCF and composite binder solution were mixed in argon, and then ball milled in an argon-protected ball mill to obtain a uniform negative electrode slurry;

[0045] The negative electrode slurry is coated on the copper foil with a doctor blade, then dried at normal pressure, vacuum dried, and then cold pressed to obtain the negative electrode sheet.

[0046] As an embodiment, the mass ratio of the nano-silicon particles, sulfide electrolyte, conductive carbon VGCF and composite binder is (20-50):(8-20):(3-8):1.

[0047] In some embodiments, the mass ratio of the nano-silicon particles, the sulfide electrolyte, the conductive carbon, and the composite binder is 70:20:8:2.

[0048] As an embodiment, the D50 of the nano-silicon particles is 30-100 nm.

[0049] In some embodiments, the D50 of the nano-silicon particles is 80 nm.

[0050] As an embodiment, the sulfide electrolyte is Li6PS5Cl, Li3PS4, Li7P3S 11 , LGPS or one or more.

[0051] In some embodiments, the sulfide electrolyte is Li6PS5Cl.

[0052] As an embodiment, the ball milling parameters are: rotation speed 200-300 rpm, and ball milling time 1-2 h.

[0053] In some embodiments, the ball milling speed is 250 rpm and the ball milling time is 1.5 h.

[0054] As an embodiment, the temperature of the normal pressure drying is 60-65° C. and the time is 2-3 hours.

[0055] As an embodiment, the vacuum degree of the vacuum drying is 0.03-0.08 MPa, the temperature is 40-80° C., and the time is 10-15 h.

[0056] <Fourth Aspect>

[0057] The present invention provides a negative electrode plate, which is prepared by adopting the above method.

[0058] <Fifth Aspect>

[0059] The present invention provides the use of the above-mentioned negative electrode plate in an all-solid-state lithium-ion battery.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] (1) The present invention first provides a composite binder solution and applies it to a sulfide all-solid-state battery silicon-based composite negative electrode. The binder having both ion conduction and elastic buffering functions is prepared by copolymerizing sodium styrene sulfonate with isoprene after ion exchange and lithiation. The binder is then compounded with PMMA in a butyl butyrate / toluene mixed solvent to form a sulfide-compatible composite binder solution. The binder is then mixed with a silicon-based material, a Li6PS5Cl electrolyte, and a conductive agent in an optimized ratio to form a slurry. After coating, step drying, and cold pressing, a high-performance composite negative electrode is obtained.

[0062] (2) The present invention develops a composite binder system that is highly compatible with sulfide electrolytes through the synergistic effect of lithium styrene sulfonate-isoprene copolymer and PMMA, wherein:

[0063] Lithium styrene sulfonate-isoprene copolymer: Through the copolymerization of lithium styrene sulfonate (ion-conducting group) and isoprene (flexible chain segment), it combines ion conductivity and elastic buffering properties. The lithium sulfonate group constructs the ion transmission channel, and the isoprene chain segment gives the binder flexibility and improves film-forming properties.

[0064] Polymethyl methacrylate (PMMA): Provides a rigid network structure, inhibiting structural collapse during silicon particle expansion, and forming a "rigid-flexible synergistic" system with the copolymer, allowing the electrode to maintain structural integrity even when the silicon material expands by 300%, resulting in excellent structural stability.

[0065] Breakthrough in electrolyte compatibility: The use of a mixed solvent of butyl butyrate and toluene, a weakly polar solvent system, prevents side reactions between the sulfide electrolyte and the polar solvent. This ensures that the composite binder system exhibits excellent solubility and film-forming properties in the butyl butyrate / toluene mixed solvent. The resulting silicon-based composite anode exhibits significantly improved interfacial stability and effectively inhibits the decomposition reaction of the sulfide electrolyte.

[0066] Ion transport optimization: The ion conduction channels constructed by the lithium sulfonate groups in the copolymer can improve interfacial ion transport and reduce ion transfer impedance, thereby enhancing the cycle stability and rate performance of sulfide all-solid-state batteries;

[0067] The process feasibility is outstanding: the preparation process is simple, the solvent can be recycled, and it has significant industrial advantages.

[0068] (3) The present invention effectively solves the problems of sulfide electrolyte decomposition, silicon volume expansion and high interface impedance in traditional systems, thereby improving the cycle stability and rate performance of sulfide all-solid-state lithium batteries. The process is also compatible with existing production lines and has significant industrial advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0070] Figure 1 This is a flow chart for preparing the lithium styrene sulfonate-isoprene copolymer, binder solution, and negative electrode sheet provided by the present invention;

[0071] Figure 2 The charge and discharge curve of a battery assembled with the negative electrode sheet prepared in Example B1 of the present invention at a rate of 0.2C;

[0072] Figure 3 The charge-discharge curve of a battery assembled with the negative electrode sheet prepared in Example B1 of the present invention at a rate of 0.5C;

[0073] Figure 4 The charge and discharge curve of a battery assembled with the negative electrode sheet prepared in comparative example BD2 of the present invention at a rate of 0.2C;

[0074] Figure 5 The charge and discharge curve of a battery assembled with the negative electrode sheet prepared in comparative example BD2 of the present invention at a rate of 0.5C;

[0075] Figure 6 The charge and discharge curve of a battery assembled with the negative electrode sheet prepared in comparative example BD5 of the present invention at a rate of 0.2C;

[0076] Figure 7 The charge and discharge curves of a battery assembled with the negative electrode sheet prepared in comparative example BD5 of the present invention at a rate of 0.5C. DETAILED DESCRIPTION

[0077] The present invention will be described in detail below with reference to the examples. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that those skilled in the art may make several adjustments and improvements without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0078] For ease of understanding, the abbreviations or nouns mentioned below are first explained:

[0079] Hydrogen form strong acidic cation exchange resin: model IR-120(H), CAS number: 9002-23-7, purchased from Aladdin Chemical Reagent Platform;

[0080] AIBN: azobisisobutyronitrile;

[0081] PMMA: polymethyl methacrylate;

[0082] VGCF: carbon nanofiber conductive agent, VGCF-H, purchased from Kejing Zhida Technology Co., Ltd.

[0083] First, the present invention provides a method for preparing a binder solution for a silicon-based negative electrode of a sulfide all-solid-state battery, such as Figure 1 As shown, the steps are:

[0084] S1. Preparation of lithium styrene sulfonate-isoprene copolymer

[0085] (1) dissolving sodium styrene sulfonate in deionized water and performing ion exchange on a hydrogen-type strongly acidic cation exchange resin column to obtain a styrene sulfonic acid solution;

[0086] (2) slowly adding a lithium hydroxide aqueous solution to the styrene sulfonic acid solution, adjusting the pH to neutral, removing the water by rotary evaporation, and performing the first drying to obtain a white powdery lithium styrene sulfonate monomer;

[0087] (3) In an argon glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), lithium styrene sulfonate and isoprene were dissolved in anhydrous toluene, and then AIBN initiator was added;

[0088] (4) Stirring in an oil bath to conduct a thermally initiated free radical copolymerization reaction. After the reaction is completed, the solution is dried for a second time to obtain a light yellow viscous lithium styrene sulfonate-isoprene copolymer;

[0089] S2. Preparation of composite binder solution

[0090] The lithium styrenesulfonate-isoprene copolymer prepared in step S1 and PMMA (Mw = 100K) were added to a mixed solvent of butyl butyrate / toluene (prepared in a mass ratio of 1:1); then mechanically stirred in a water bath to obtain a uniform and transparent binder solution (labeled as Bi).

[0091] The solid content of the prepared composite binder solution is 5 wt.%.

[0092] Solid content = (mass of lithium styrene sulfonate-isoprene copolymer + mass of PMMA) / total mass of binder solution × 100%.

[0093] The following is a detailed introduction to the preparation method of the binder solution for the silicon-based negative electrode of the sulfide all-solid-state battery through several examples, as shown in Table 1 and Table 2 for details.

[0094] Table 1

[0095]

[0096] Table 2

[0097]

[0098] Comparative Example AD1

[0099] This comparative example provides a method for preparing a composite binder solution that does not contain lithium styrene sulfonate. The steps are basically the same as those in Example A1, except that:

[0100] In step S1, steps (1) and (2) are eliminated, and in step (3), only isoprene is dissolved in anhydrous toluene and AIBN initiator is added, and then step (4) is performed to obtain a copolymer free of lithium styrene sulfonate, and the copolymer is applied to step S2.

[0101] Other parameters refer to Example A1.

[0102] The obtained composite binder solution was labeled Bi3.

[0103] Comparative Example AD2

[0104] This comparative example provides a method for preparing a composite binder solution that does not contain isoprene. The steps are basically the same as those in Example A1, except that:

[0105] In step S1, in step (3), only lithium styrene sulfonate is dissolved in anhydrous toluene and AIBN initiator is added, and then step (4) is performed to obtain a copolymer free of isoprene; and the copolymer is applied to step S2.

[0106] Other parameters refer to Example A1.

[0107] The obtained composite binder solution was labeled Bi4.

[0108] Comparative Example AD3

[0109] This comparative example provides a method for preparing a composite binder solution that does not contain toluene. The steps are basically the same as those in Example A1, except that:

[0110] In step S2, the butyl butyrate / toluene mixed solvent is replaced with an equal volume of butyl butyrate without toluene.

[0111] Other parameters refer to Example A1.

[0112] The obtained composite binder solution was labeled Bi5.

[0113] Comparative Example AD4

[0114] This comparative example provides a method for preparing a composite binder solution that does not contain butyl butyrate. The steps are basically the same as those in Example A1, except that:

[0115] In step S2, the butyl butyrate / toluene mixed solvent is replaced with an equal volume of toluene without butyl butyrate.

[0116] Other parameters refer to Example A1.

[0117] The obtained composite binder solution was labeled Bi6.

[0118] Detection and Analysis 1

[0119] The slurry state analysis of the binder solution is shown in Table 3.

[0120] Table 3

[0121]

[0122] It can be seen that the composite binder solutions prepared in Examples A1 and A2 have appropriate viscosity, no precipitation or agglomeration, and are in a slurry state better than that of the comparative example.

[0123] The following describes a method for preparing a sulfide all-solid-state battery silicon-based negative electrode sheet using the composite binder solution prepared above by a wet film forming method. Figure 1 As shown, the steps are:

[0124] In argon, nano-silicon particles, Li6PS5Cl electrolyte, conductive carbon VGCF and binder Bi are mixed, and then ball milled in an argon-protected ball mill to obtain a uniform negative electrode slurry;

[0125] The negative electrode slurry was coated on a 10 μm thick copper foil (wet film thickness 200 μm) with a doctor blade, then dried at normal pressure, vacuum dried, and then cold pressed to obtain a negative electrode sheet.

[0126] The following is a detailed introduction to the preparation method of the negative electrode sheet through several examples, see Table 4 for details.

[0127] Table 4

[0128]

[0129] Detection and Analysis 2

[0130] The film formation status of the negative electrode sheet was analyzed, and the results are listed in Table 5.

[0131] Table 5

[0132]

[0133] It can be seen that the negative electrode sheets prepared in Examples B1 and B2 have smooth surfaces without protrusions or depressions, and the film-forming state is better than that of the comparative example.

[0134] Detection and Analysis 3

[0135] The prepared negative electrode sheet is used for performance analysis of all-solid-state lithium-ion batteries.

[0136] First, the preparation of the all-solid-state lithium-ion battery is carried out in the following steps:

[0137] 80 mg of NCM811 powder, 15 mg of Li6PS5Cl sulfide solid electrolyte, and 5 mg of conductive agent VGCF powder were placed in a mortar and ground for 30 min to prepare a composite positive electrode powder;

[0138] In an argon-filled glove box, 30 mg of Li6PS5Cl sulfide electrolyte powder was placed in a 10 mm diameter pressure cell mold and pressed into tablets on a tablet press. A pressure of 1 ton was applied and the pressure was maintained for 1 min.

[0139] Spread 30 mg of composite cathode powder on the surface of the electrolyte sheet, apply 1 ton of pressure, and maintain the pressure for 1 minute;

[0140] The negative electrode sheet prepared in the above embodiment or comparative example was cut into a disc with a diameter of 10 mm, laid flat on the other side of the electrolyte sheet with the copper foil facing outward, and a pressure of 1 ton was applied and maintained for 1 minute;

[0141] A 15 μm thick, 10 mm diameter aluminum foil was placed on the surface of the composite positive electrode sheet as the positive electrode current collector. After assembly, a pressure of 1 ton was applied and maintained for 1 minute.

[0142] A sulfide all-solid-state lithium-ion battery was obtained.

[0143] Then, the Xinwei battery testing system (model CT-4000) was used to perform charge and discharge tests on the prepared all-solid-state lithium-ion batteries. A 0.2C-0.5C rate charge and discharge process was used, with a voltage range of 4.3-2.5V and a temperature of 28°C. The discharge capacity of the sulfide all-solid-state battery was tested. The relevant battery performance data are listed in Table 6.

[0144] The charge and discharge curves of the batteries assembled with the corresponding negative electrode sheets of Example B1, Comparative Example BD2 and Comparative Example BD5 at a rate of 0.2C are shown as follows: Figure 2 、 Figure 4 and Figure 6 shown.

[0145] The charge and discharge curves of the batteries assembled with the corresponding negative electrode sheets of Example B1, Comparative Example BD2 and Comparative Example BD5 at a rate of 0.5C are shown as follows: Figure 3 、 Figure 5 and Figure 7 shown.

[0146] Table 6

[0147]

[0148] It can be seen that the discharge capacity at 0.2C and 0.5C, coulombic efficiency and capacity retention rate after 30 cycles of the all-solid-state battery assembled by the negative electrode sheets prepared in Examples B1 and BD2 are significantly higher than those of Comparative Examples BD1 to BD5. This is mainly because the ion conduction channels constructed by the lithium sulfonate groups in the lithium styrene sulfonate-isoprene copolymer can improve the interfacial ion transport. At the same time, the flexible isoprene segments and the rigid PMMA network in the copolymer work synergistically, so that the electrode maintains structural integrity under 300% volume expansion of the silicon material. The prepared silicon-based composite negative electrode has significantly improved interface stability, which can effectively inhibit the decomposition reaction of the sulfide electrolyte, thereby improving the cycle stability and rate performance of the sulfide all-solid-state battery.

[0149] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a composite binder solution, characterized in that: The following steps are involved: Lithium styrene sulfonate-isoprene copolymer and polymethyl methacrylate are added to a mixed solvent of butyl butyrate and toluene, and stirred uniformly to obtain the composite binder solution, wherein the mass ratio of lithium styrene sulfonate-isoprene copolymer to polymethyl methacrylate is 9-21:9, the mass ratio of butyl butyrate to toluene in the mixed solvent is 0.5-2:1, and the mass ratio of lithium styrene sulfonate to isoprene is 0.93-2.80:

1.

2. The method according to claim 1, characterized in that The preparation method of the lithium styrene sulfonate-isoprene copolymer comprises the following steps: dissolving lithium styrene sulfonate and isoprene in anhydrous toluene under a protective atmosphere, adding an initiator, and performing a thermally initiated free radical copolymerization reaction; and vacuum drying to obtain the lithium styrene sulfonate-isoprene copolymer.

3. The method according to claim 2, characterized in that It also includes one or more of the following technical features: The molar ratio of A1, lithium styrene sulfonate to isoprene is 1:1-3; B1, the amount of the initiator is 0.5-1.5 wt.% of the mass of lithium styrene sulfonate; The ratio of C1, lithium styrene sulfonate and anhydrous toluene is 1g: 5-15g; D1. The temperature of the free radical copolymerization reaction is 60-80°C and the reaction time is 8-12 hours.

4. The method according to claim 2, characterized in that The preparation method of the lithium styrene sulfonate comprises: using a lithium hydroxide aqueous solution to neutralize a styrene sulfonic acid aqueous solution to neutralize the solution, and extracting the product to obtain the lithium styrene sulfonate.

5. The method according to claim 4, characterized in that The preparation method of the styrenesulfonic acid aqueous solution is as follows: passing the sodium styrenesulfonate aqueous solution through a hydrogen-type strongly acidic cation exchange resin column for ion exchange to obtain the styrenesulfonic acid aqueous solution.

6. A composite binder solution, characterized in that: It is prepared according to the method according to any one of claims 1 to 5.

7. A method for preparing a negative electrode sheet, characterized in that: The following steps are involved: In argon, nano-silicon particles, sulfide electrolyte, conductive carbon VGCF and the composite binder solution as claimed in claim 6 are mixed, and then ball milled in an argon-protected ball mill to obtain a uniform negative electrode slurry; The negative electrode slurry is coated on the copper foil with a doctor blade, then dried at normal pressure, vacuum dried, and then cold pressed to obtain the negative electrode sheet.

8. The method according to claim 7, characterized in that It also includes one or more of the following technical features: A2, the mass ratio of the nano-silicon particles, sulfide electrolyte, conductive carbon VGCF and composite binder is (20-50): (8-20): (3-8): 1; B2, D50 of the nano-silicon particles = 30-100 nm; C2, the sulfide electrolyte is Li6PS5Cl, Li3PS4, Li7P3S 11 , one or more of LGPS; D2, the ball milling parameters are: rotation speed 200~300rpm, ball milling time 1~2h; E2, the temperature of the atmospheric pressure drying is 60-65°C and the time is 2-3 hours; F2. The vacuum degree of the vacuum drying is 0.03-0.08 MPa, the temperature is 40-80° C., and the time is 10-15 h.

9. A negative electrode plate, characterized in that: It is prepared according to the method of claim 7 or 8.

10. Use of the negative electrode sheet according to claim 9 in an all-solid-state lithium battery.

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