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

Abstract

The invention discloses a composite binder, a preparation method of the composite binder and application of the composite binder in a negative electrode of an all-solid-state lithium ion battery, and relates to the technical field of all-solid-state lithium batteries. Sodium p-styrenesulfonate is subjected to ion exchange and lithiation and then is copolymerized with isoprene to prepare the binder with ionic conduction and elastic buffering functions; then compounding with PMMA (polymethyl methacrylate) in a butyl butyrate / methylbenzene mixed solvent to form a sulfide-compatible composite binder solution; and mixing the binder with a silicon-based material, a Li6PS5Cl electrolyte and a conductive agent according to an optimized ratio to prepare slurry, and carrying out coating, stepped drying and cold pressing to obtain the high-performance composite negative electrode. The problems of sulfide electrolyte decomposition, silicon volume expansion, high interface impedance and the like in a traditional system are effectively solved, the cycling stability and the rate capability of the sulfide all-solid-state lithium battery are improved, and the process is adaptive to an existing production line and has remarkable industrialization advantages.

Description

Technical Field

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

[0002] With the increasing 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 300 Wh / kg and inherent safety. However, there are many technical bottlenecks in the wet preparation process of silicon-based composite negative electrodes, especially the interfacial compatibility problem between the silicon-based composite negative electrode and the sulfide electrolyte: First of all, sulfide solid electrolytes are extremely sensitive to conventional polar solvents (such as NMP, DMF, etc.). After contact, irreversible chemical decomposition reactions will occur, which will not only produce toxic gases such as H2S, but also form an insulating layer at the interface, resulting in a decrease in ionic conductivity by more than two orders of magnitude, directly damaging the electrochemical performance of the battery; Secondly, the solubility and dispersibility of traditional binder systems (such as PVDF, PAA, CMC, etc.) in low-polarity solvents are poor, and it is difficult to form a uniform and stable slurry. After film formation, cracks and holes are likely to appear, seriously affecting the integrity of the electrode structure; Furthermore, the volume change of silicon materials during charge and discharge is as high as 300%, which will damage the close contact at the electrode-electrolyte interface, leading to a continuous increase in interfacial impedance. Although polymethyl methacrylate (PMMA) is a binder that can be used for conventional silicon negative electrodes and has a certain inhibitory effect on the volume expansion of silicon, its film-forming rigidity is too strong and its toughness is insufficient. When used alone, the electrode structure is likely to crack due to silicon expansion; In addition, the core contradiction of the existing binder system lies in that traditional binders cannot simultaneously meet the four key requirements of chemical compatibility with sulfide electrolytes, buffer adaptability to silicon volume expansion, sufficient mechanical support strength, and ionic conduction ability.

[0003] These problems seriously restrict the performance improvement and industrialization process of sulfide all-solid-state batteries, and it is urgent to develop a new solvent-binder synergistic system to break through these technical barriers. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a composite binder, a preparation method thereof, and an application thereof in the negative electrode of an all-solid-state lithium-ion battery.

[0005] The purpose of the present invention is achieved by the following technical solutions: <The First Aspect> The present invention provides a preparation method of a composite binder solution, comprising the following steps: Dissolve lithium styrene sulfonate-isoprene copolymer and polymethyl methacrylate in a mixed solvent of butyl butyrate and toluene, and blend them to obtain the composite binder solution.

[0006] As an embodiment, the mass ratio of lithium styrene sulfonate-isoprene copolymer to polymethyl methacrylate is 9-21:9.

[0007] In some embodiments, the mass ratio of lithium styrene sulfonate-isoprene copolymer to polymethyl methacrylate is 11-13.5:9.

[0008] As an embodiment, the mass ratio of butyl butyrate to toluene in the mixed solvent is 0.5-2:1.

[0009] In some embodiments, the mass ratio of butyl butyrate to toluene in the mixed solvent is 1:1.

[0010] As an embodiment, the solid content of the composite binder solution is 4-8 wt.%.

[0011] In some embodiments, the solid content of the composite binder solution is 5 wt.%.

[0012] As an embodiment, the blending is carried out at a temperature of 40-80 °C.

[0013] In some embodiments, the blending is carried out at 50 °C.

[0014] As an embodiment, the preparation method of the lithium styrene sulfonate-isoprene copolymer is as follows: under a protective atmosphere, dissolve lithium styrene sulfonate and isoprene in anhydrous toluene, then add an initiator, and carry out thermal-initiated free radical copolymerization reaction. After vacuum drying, the lithium styrene sulfonate-isoprene copolymer is obtained.

[0015] As an embodiment, the initiator is selected from one or more of AIBN, benzoyl peroxide (BPO), dicumyl peroxide (DCP), and azodiisobutyronitrile (ABVN).

[0016] In some embodiments, the initiator is selected as AIBN.

[0017] As an embodiment, the molar ratio of lithium styrene sulfonate to isoprene is 1:1-3.

[0018] As an embodiment, the mass ratio of lithium styrene sulfonate to isoprene is 0.93-2.80:1.

[0019] In some embodiments, the mass ratio of lithium styrene sulfonate to isoprene is 1.35-1.80:1.

[0020] As an embodiment, the dosage of the initiator is 0.5 to 1.5 wt.% of the mass of lithium styrenesulfonate.

[0021] In some embodiments, the dosage of the initiator is 1.2 wt.% or 1.5 wt.% of the mass of lithium styrenesulfonate.

[0022] As an embodiment, the dosage ratio of lithium styrenesulfonate to anhydrous toluene is 1 g : 5 to 15 g.

[0023] In some embodiments, the dosage ratio of lithium styrenesulfonate to anhydrous toluene is 1 g : 10 g.

[0024] In some embodiments, the temperature of the free radical copolymerization reaction is 60 to 80 °C, and the reaction time is 8 to 12 h.

[0025] In some embodiments, the temperature of the free radical copolymerization reaction is 65 to 70 °C, and the reaction time is 10 to 12 h.

[0026] As an embodiment, the preparation method of the lithium styrenesulfonate is as follows: neutralize the aqueous solution of styrenesulfonic acid with an aqueous solution of lithium hydroxide to neutrality, and extract the product to obtain the lithium styrenesulfonate.

[0027] As an embodiment, the concentration of the aqueous solution of lithium hydroxide is 5 to 10 wt.%.

[0028] In some embodiments, the concentration of the aqueous solution of lithium hydroxide is 8 to 10 wt.%.

[0029] As an embodiment, the preparation method of the aqueous solution of styrenesulfonic acid is as follows: perform ion exchange on the aqueous solution of sodium styrenesulfonate through a hydrogen-type strongly acidic cation exchange resin column to obtain the aqueous solution of styrenesulfonic acid.

[0030] As an embodiment, the concentration of the aqueous solution of styrenesulfonic acid is 0.001 to 0.05 g / mL.

[0031] In some embodiments, the concentration of the aqueous solution of styrenesulfonic acid is 0.01 g / mL.

[0032] As an embodiment, the vacuum degree of the vacuum drying is 0.03 to 0.08 MPa, the temperature is 40 to 80 °C, and the time is 10 to 15 h.

[0033] <Second aspect> The present invention provides a binder prepared by the above method.

[0034] <Third aspect> The present invention provides a method for using the above composite binder solution to prepare a negative electrode sheet, comprising the following steps: Mix the nano-silicon particles, Li6PS5Cl electrolyte, conductive carbon VGCF and the composite binder solution in argon, and then carry out ball milling in a ball mill under argon protection to obtain a uniform negative electrode slurry; Coat the negative electrode slurry on a copper foil with a doctor blade, then carry out atmospheric drying, then carry out vacuum drying, and then cold press to form a negative electrode sheet.

[0035] As an embodiment, the mass ratio of the nano-silicon particles, sulfide electrolyte, conductive carbon VGCF to the composite binder is (20 - 50):(8 - 20):(3 - 8):1.

[0036] In some embodiments, the mass ratio of the nano-silicon particles, sulfide electrolyte, conductive carbon to the composite binder is 70:20:8:2.

[0037] As an embodiment, the D50 of the nano-silicon particles is 30 - 100 nm.

[0038] In some embodiments, the D50 of the nano-silicon particles is 80 nm.

[0039] As an embodiment, the sulfide electrolyte is one or more of Li6PS5Cl, Li3PS4, Li7P3S 11 , LGPS.

[0040] In some embodiments, the sulfide electrolyte is Li6PS5Cl.

[0041] As an embodiment, the ball milling parameters are: rotation speed 200 - 300 rpm, ball milling time 1 - 2 h.

[0042] In some embodiments, the ball milling rotation speed is 250 rpm, and the ball milling time is 1.5 h.

[0043] As an embodiment, the temperature of the atmospheric drying is 60 - 65 °C, and the time is 2 - 3 h.

[0044] 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.

[0045] <Fourth aspect> The present invention provides a negative electrode sheet prepared by the above method.

[0046] <Fifth aspect> The present invention provides the application of the above negative electrode sheet in a all-solid-state lithium-ion battery.

[0047] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention first provides a composite binder solution and applies it to the silicon-based composite anode of a sulfide all-solid-state battery. By copolymerizing sodium styrene sulfonate with isoprene after ion exchange and lithiation, a binder with both ion conduction and elastic buffering functions is obtained, and then it is compounded with PMMA in a butyl butyrate / toluene mixed solvent to form a sulfide-compatible composite binder solution; then the binder is mixed with a silicon-based material, Li6PS5Cl electrolyte, and a conductive agent in an optimized ratio to make a slurry, and a high-performance composite anode is obtained after coating, step drying, and cold pressing.

[0048] (2) Through the synergistic effect of lithium styrene sulfonate-isoprene copolymer and PMMA, the present invention develops a composite binder system that is highly compatible with sulfide electrolytes. Among them, Lithium styrene sulfonate-isoprene copolymer: By copolymerizing lithium styrene sulfonate (ion conduction group) with isoprene (flexible chain segment), it has both ion conduction ability and elastic buffering performance. Among them, the sulfonate lithium group constructs an ion transport channel, and the isoprene chain segment endows the binder with flexibility and improves the film-forming property; Polymethyl methacrylate (PMMA): Provides a rigid network structure, inhibits the structural collapse during the expansion of silicon particles, and forms a "rigid-flexible synergy" system with the copolymer, enabling the electrode to maintain structural integrity even under 300% volume expansion of silicon materials and having excellent structural stability; Breakthrough in electrolyte compatibility: The mixed solvent of butyl butyrate and toluene is used, which belongs to a weakly polar solvent system, avoiding side reactions between sulfide electrolytes and polar solvents. At the same time, it ensures that the composite binder system exhibits excellent solubility and film-forming property in the butyl butyrate / toluene mixed solvent. The prepared silicon-based composite anode has significantly improved interfacial stability and can effectively inhibit the decomposition reaction of sulfide electrolytes; Optimization of ion transport: The ion conduction channel constructed by the sulfonate lithium group in the copolymer can improve interfacial ion transport, reduce ion transfer impedance, and thus enhance the cycle stability and rate performance of sulfide all-solid-state batteries; Outstanding process feasibility: The preparation process is simple, the solvent can be recycled, and it has significant industrialization advantages.

[0049] (3) The present invention effectively solves the problems of sulfide electrolyte decomposition, silicon volume expansion, and high interfacial impedance in traditional systems, improves the cycle stability and rate performance of sulfide all-solid-state lithium batteries, and the process is compatible with existing production lines, having significant industrialization advantages. Description of the Drawings

[0050] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments read in conjunction with the accompanying drawings: Figure 1 A preparation flow chart of a lithium styrene sulfonate-isoprene copolymer, a binder solution, and a negative electrode sheet provided by the present invention; Figure 2 A charge-discharge curve of a battery assembled with the negative electrode sheet prepared in Example B1 of the present invention at a rate of 0.2C; Figure 3 A 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; Figure 4 A charge-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; Figure 5 A charge-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; Figure 6 A charge-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; Figure 7 A charge-discharge curve of a battery assembled with the negative electrode sheet prepared in Comparative Example BD5 of the present invention at a rate of 0.5C. Detailed Description of the Invention

[0051] The present invention will be described in detail below in conjunction with embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those of ordinary skill in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0052] For ease of understanding, the abbreviations or nouns mentioned in the following text are first explained: Hydrogen-type strongly acidic cation exchange resin: Model IR-120(H), CAS No.: 9002-23-7, purchased from the Aladdin chemical reagent platform; AIBN: Azobisisobutyronitrile; PMMA: Polymethyl methacrylate; VGCF: Carbon nanofiber conductive agent, VGCF-H, purchased from Kejing Zhida Technology Co., Ltd.

[0053] 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, as Figure 1 shown, the steps are: S1. Prepare a lithium styrene sulfonate-isoprene copolymer (1) Dissolve sodium styrene sulfonate in deionized water, and perform ion exchange through a hydrogen-form strongly acidic cation exchange resin column to obtain a styrene sulfonic acid solution; (2) Slowly dropwise add an aqueous lithium hydroxide solution to the styrene sulfonic acid solution, adjust the pH to neutral, remove the water by rotary evaporation, and then perform the first drying to obtain a white powdery lithium styrene sulfonate monomer; (3) In an argon glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), dissolve lithium styrene sulfonate and isoprene in anhydrous toluene, and then add an AIBN initiator; (4) Stir in an oil bath to carry out a thermal-initiated radical copolymerization reaction. After the reaction is completed, perform the second drying on the solution to obtain a pale yellow viscous lithium styrene sulfonate-isoprene copolymer; S2. Preparation of a composite binder solution Add the lithium styrene sulfonate-isoprene copolymer prepared in step S1 and PMMA (Mw = 100K) to a mixed solvent of butyl butyrate / toluene (prepared according to a mass ratio of 1:1); then perform mechanical stirring in a water bath to obtain a uniform and transparent binder solution (labeled as Bi).

[0054] The solid content of the prepared composite binder solution is 5 wt.%.

[0055] Solid content = (mass of lithium styrene sulfonate-isoprene copolymer + mass of PMMA) / total mass of the binder solution × 100%.

[0056] The following specifically introduces the preparation method of the binder solution for the silicon-based anode of a sulfide all-solid-state battery through several examples, as shown in Tables 1 and 2.

[0057] Table 1

[0058] Table 2

[0059] Comparative example AD1 This comparative example provides a preparation method of a composite binder solution without lithium styrene sulfonate. The steps are basically the same as those in Example A1, and the difference is that: In step S1, cancel steps (1) and (2). In step (3), only dissolve isoprene in anhydrous toluene, add an AIBN initiator, and then perform step (4) to obtain a copolymer without lithium styrene sulfonate, and apply this copolymer to step S2.

[0060] Other parameters refer to Example A1.

[0061] The obtained composite binder solution is labeled as Bi3.

[0062] Comparative Example AD2 This comparative example provides a method for preparing a composite binder solution without isoprene. The steps are basically the same as those in Example A1, and the differences are as follows: In step S1, in step (3), only lithium styrenesulfonate is dissolved in anhydrous toluene, and an AIBN initiator is added, and then step (4) is carried out to obtain a copolymer without isoprene; and this copolymer is applied to step S2.

[0063] Other parameters refer to Example A1.

[0064] The obtained composite binder solution is labeled as Bi4.

[0065] Comparative Example AD3 This comparative example provides a method for preparing a composite binder solution without toluene. The steps are basically the same as those in Example A1, and the differences are as follows: In step S2, the butyl butyrate / toluene mixed solvent is replaced with the same volume of butyl butyrate without toluene.

[0066] Other parameters refer to Example A1.

[0067] The obtained composite binder solution is labeled as Bi5.

[0068] Comparative Example AD4 This comparative example provides a method for preparing a composite binder solution without butyl butyrate. The steps are basically the same as those in Example A1, and the differences are as follows: In step S2, the butyl butyrate / toluene mixed solvent is replaced with the same volume of toluene without butyl butyrate.

[0069] Other parameters refer to Example A1.

[0070] The obtained composite binder solution is labeled as Bi6.

[0071] Detection and Analysis 1 Analysis of the slurry state of the binder solution, and the results are shown in Table 3.

[0072] Table 3

[0073] It can be seen that the viscosities of the composite binder solutions prepared in Examples A1 and A2 are appropriate, there is no precipitation and agglomeration, and the slurry state is better than that of the comparative examples.

[0074] The following introduces a method for preparing a silicon-based negative electrode sheet of a sulfide all-solid-state battery by a wet film-forming method using the above-prepared composite binder solution, asFigure 1 As shown, the steps are as follows: In argon, mix nano-silicon particles, Li6PS5Cl electrolyte, conductive carbon VGCF, and binder Bi, and then perform ball milling in a ball mill under argon protection to obtain a uniform negative electrode slurry. Coat the negative electrode slurry on a 10-μm-thick copper foil with a doctor blade (wet film thickness: 200 μm), then perform drying at atmospheric pressure, followed by vacuum drying, and then cold pressing to obtain a negative electrode sheet.

[0075] The preparation method of the negative electrode sheet will be specifically introduced through several embodiments as shown in Table 4.

[0076] Table 4

[0077] Detection and analysis II The film formation state of the negative electrode sheet was analyzed, and the results are listed in Table 5.

[0078] Table 5

[0079] It can be seen that the negative electrode sheets prepared in Examples B1 and B2 have a flat surface without protrusions or depressions, and the film formation state is better than that of the comparative examples.

[0080] Detection and analysis III Performance analysis of the prepared negative electrode sheet applied to all-solid-state lithium-ion batteries.

[0081] First, the preparation of all-solid-state lithium-ion batteries is carried out, and the steps are as follows: Place 80 mg of NCM811 powder, 15 mg of Li6PS5Cl sulfide solid electrolyte, and 5 mg of conductive agent VGCF powder in a mortar and grind for 30 min to prepare a composite positive electrode powder. Operate in a glove box filled with argon. Place 30 mg of Li6PS5Cl sulfide electrolyte powder in a pressure battery mold with a diameter of 10 mm, and press it into a sheet on a tablet press, applying a pressure of 1 ton and maintaining the pressure for 1 min. Lay 30 mg of the composite positive electrode powder flat on the surface of the electrolyte sheet, apply a pressure of 1 ton, and maintain the pressure for 1 min. Cut the negative electrode sheet prepared in the above examples or comparative examples into a 10-mm-diameter circular piece, lay it flat on the other side of the electrolyte sheet with the copper foil facing outward, apply a pressure of 1 ton, and maintain the pressure for 1 min. Place a 15-μm-thick and 10-mm-diameter aluminum foil on the surface of the composite positive electrode sheet as the positive electrode current collector, and apply a pressure of 1 ton after assembly and maintain the pressure for 1 min. Obtain a sulfide all-solid-state lithium-ion battery.

[0082] Then, a Neware battery test system with the device model CT-4000 was used to conduct charge-discharge tests on each of the prepared all-solid-state lithium-ion batteries. The charge-discharge steps with a rate of 0.2C - 0.5C were used, the voltage range was 4.3 - 2.5V, the temperature was 28°C, and the discharge capacity of the sulfide all-solid-state battery was tested. The relevant battery performance data are listed in Table 6.

[0083] The charge-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 respectively as Figure 2 、 Figure 4 and Figure 6 shown.

[0084] The charge-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 respectively as Figure 3 、 Figure 5 and Figure 7 shown.

[0085] Table 6

[0086] It can be seen that the discharge capacities, Coulomb efficiencies, and capacity retention rates after 30 cycles at 0.2C and 0.5C of the all-solid-state batteries assembled with the negative electrode sheets prepared in Example 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 styrene sulfonic acid lithium-isoprene copolymer can improve the interfacial ion transport. At the same time, the flexible isoprene chain segments and the rigid PMMA network in the copolymer act synergistically, enabling the electrode to maintain structural integrity even under a 300% volume expansion of the silicon material. The prepared silicon-based composite negative electrode has significantly improved interfacial stability, which can effectively inhibit the decomposition reaction of the sulfide electrolyte, thereby enhancing the cycle stability and rate performance of the sulfide all-solid-state battery.

[0087] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various deformations 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 It includes the following steps: Add lithium styrene sulfonate-isoprene copolymer and polymethyl methacrylate into the mixed solvent of butyl butyrate and toluene, and stir evenly to obtain the composite binder solution.

2. The method according to claim 1, wherein The preparation method of the lithium styrene sulfonate-isoprene copolymer is as follows: under a protective atmosphere, dissolve lithium styrene sulfonate and isoprene in anhydrous toluene, then add an initiator, and carry out thermal-initiated free radical copolymerization reaction. After vacuum drying, the lithium styrene sulfonate-isoprene copolymer is obtained.

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

4. The method according to claim 2, wherein The preparation method of the lithium styrene sulfonate is as follows: neutralize the aqueous solution of styrene sulfonic acid with an aqueous solution of lithium hydroxide to neutrality, and extract the product to obtain the lithium styrene sulfonate.

5. The method according to claim 4, wherein The preparation method of the aqueous solution of styrene sulfonic acid is as follows: pass the aqueous solution of sodium styrene sulfonate through a hydrogen-type strongly acidic cation exchange resin column for ion exchange to obtain the aqueous solution of styrene sulfonic acid.

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

7. A method for preparing a negative electrode plate, characterized in that, It includes the following steps: In argon, mix nano-silicon particles, sulfide electrolyte, conductive carbon VGCF with the composite binder solution as described in claim 6, and then carry out ball milling in a ball mill protected by argon to obtain a uniform negative electrode slurry. Coat the negative electrode slurry on the copper foil with a doctor blade, then carry out atmospheric drying, then vacuum drying, and then cold pressing to form a negative electrode sheet.

8. The method according to claim 7, wherein 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 to the composite binder is (20-50):(8-20):(3-8):1; B2. The D50 of the nano-silicon particles is 30~100 nm; C2. The sulfide electrolyte is one or more of Li6PS5Cl, Li3PS4, Li7P3S 11 , and LGPS; D2. The ball milling parameters are: rotation speed 200~300 rpm, and the ball milling time is 1~2h; E2. The temperature of the atmospheric drying is 60~65 °C, and the time is 2~3h; F2. The vacuum degree of the vacuum drying is 0.03~0.08 MPa, the temperature is 40~80 °C, and the time is 10~15h.

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

10. Application of the negative electrode sheet described in claim 9 in a all-solid-state lithium battery.

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