Preparation method of electrochemically pre-lithiated silicon-based negative electrode slurry

Abstract

The invention discloses an electrochemical pre-lithiation silicon-based negative electrode slurry preparation method, which comprises: S1, carrying out ball milling treatment on a solid electrolyte to obtain a first ball-milled slurry; s2, adding a silicon-based material, graphite, a conductive agent, an adhesive, a lithium salt and a film-forming additive into the first ball-milled slurry, and stirring to obtain second slurry; s3, the second slurry is poured into an electrochemical pre-lithiation device, electrochemical pre-lithiation is conducted on the second slurry, and the silicon-based negative electrode slurry subjected to electrochemical pre-lithiation is obtained and has the advantages of being high in lithium supplementing efficiency, low in environment requirement and uniform in lithium supplementing.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation, and particularly relates to a method for preparing electrochemically pre-lithiated silicon-based anode slurry. Background Technology

[0002] Currently, the energy density requirements for lithium-ion batteries in fields such as electric vehicles, mobile phones, and power tools are continuously increasing. Traditional battery systems using high-nickel cathodes paired with graphite anodes are limited to an energy density upper limit of below 300Wh / kg due to the theoretical specific capacity of the graphite anode being only 372mAh / g, making it difficult to meet the upgrade demands of these scenarios. Silicon-based anode materials, on the other hand, possess a theoretical specific capacity as high as 4200mAh / g (corresponding to the Li-Si alloy Li...). x Si, 0 < x With an energy density of ≤4.4, it is more than 10 times that of traditional graphite anodes and is recognized as the core direction for the next generation of anode materials that breaks through the energy density bottleneck.

[0003] However, silicon-based materials have two major drawbacks during lithium intercalation: First, lithium intercalation results in a 2-3 times volume expansion (the more lithium intercalated, the greater the expansion), leading to a sharp drop in material surface stability and causing rapid capacity decay in the battery. Second, even if the size of silicon materials is reduced to the nanometer scale (10-100nm) through processes such as ball milling and CVD, although the volume expansion can be alleviated, a large amount of SEI film will still form on the silicon surface, continuously consuming active lithium. Moreover, if surface stability cannot be maintained during charge-discharge cycles, the problem of active lithium consumption will recur.

[0004] To improve the surface stability of silicon-based materials, existing technologies mainly employ carbon coating processes. However, the carbon coating layer is brittle and prone to localized cracking during silicon lithium intercalation and expansion, leading to the exposure of the silicon-based material to the electrolyte and exacerbating the stability decline. Regarding lithium replenishment technology, existing solutions are divided into positive electrode lithium replenishment and negative electrode lithium replenishment. The mainstream methods for negative electrode lithium replenishment include: lithium metal sheet rolling (strict environmental requirements, high cost), addition of stable lithium metal powder (poor mixing and lithium replenishment uniformity), chemical lithium replenishment (difficult to control the amount of lithium replenished, low efficiency), and traditional electrochemical lithium replenishment (treating the electrode sheet as the processing target, limited coating amount leading to low efficiency, high electrode activity after lithium replenishment, high environmental requirements, and safety hazards).

[0005] In summary, existing technologies cannot simultaneously address the four core requirements of "high lithium replenishment efficiency, low environmental requirements, good lithium replenishment uniformity, and strong silicon-based surface stability." Therefore, there is an urgent need to design a method for preparing electrochemically pre-lithiated silicon-based anode slurry to solve the aforementioned problems. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing electrochemically pre-lithiated silicon-based anode slurry, which has the advantages of high lithium replenishment efficiency, low environmental requirements, and uniform lithium replenishment.

[0007] To achieve the above objectives, the specific technical solution of the present invention for preparing an electrochemically pre-lithiated silicon-based anode slurry is as follows: A method for preparing an electrochemically pre-lithiated silicon-based anode slurry includes the following steps: S1: The solid electrolyte is ball-milled to obtain the first ball-milled slurry; S2: Add silicon-based material, graphite, conductive agent, binder, lithium salt and film-forming additive to the first ball milling slurry and stir to obtain a second slurry; S3: Pour the second slurry into the electrochemical pre-lithiation device and perform electrochemical pre-lithiation on the second slurry to obtain an electrochemically pre-lithiated silicon-based anode slurry.

[0008] Furthermore, the electrochemical pre-lithiation device includes, from the outside in, an electrolyte layer, a negative electrode current collector layer, a solid electrolyte membrane, and a stirred tank surrounded by the solid electrolyte membrane. A positive electrode current collector is provided inside the stirred tank. The positive electrode current collector is a stirring paddle, which is used to stir the second slurry in the stirred tank so that the second slurry can undergo electrochemical pre-lithiation.

[0009] Furthermore, the mass ratio of the silicon-based material, the solid electrolyte, the graphite, the film-forming additive, the lithium salt, the binder, and the conductive agent is 4~50:10~25:40~80:2~6:0.5~5:5~10:3~10.

[0010] Furthermore, the solid electrolyte uses Li 0.33 La 0.56 TiO3(LLTO), Li7La3Zr2O 12 (LLZO), Li 1.4 Al 0.4 Ti 1.6 (PO4)3 (LATP), Li4Ti5O 12 One or a combination of (LTO) and LiAlO2 (LAO).

[0011] Furthermore, the initial particle size range of the solid electrolyte is 0.5~20μm, and the particle size of the solid electrolyte after ball milling is less than 100nm.

[0012] Furthermore, the silicon-based material is a silicon-carbon anode material, and the specific capacity of the silicon-carbon anode material is in the range of 450~1800mAh / g.

[0013] Furthermore, the degree of pre-lithiation of the electrochemically pre-lithiated silicon-based anode slurry is 5-30% of the total capacity of the active material in the electrochemically pre-lithiated silicon-based anode slurry.

[0014] Furthermore, the lithium salt is one or a combination of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium bis(oxalate-borate) (LiBOB), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorooxalate-borate) (LiODFB), lithium perchlorate (LiClO4), and lithium chloride (LiCl).

[0015] Furthermore, step S1 also includes the following step: simultaneously ball milling the solid electrolyte and the dispersant to obtain a first ball mill slurry.

[0016] Furthermore, the film-forming additive is one or a combination of citric acid, malic acid, ascorbic acid (VC), fruit acid, sorbic acid, tartaric acid, vinylene carbonate (VC), fluoroethylene carbonate (FEC), ethylene ethylene carbonate (VEC), and 1,3-propanesulfonyl lactone (1,3-PS).

[0017] The method for preparing electrochemically pre-lithiated silicon-based anode slurry of the present invention has the following advantages: 1. The use of "slurry form" instead of the traditional "electrode form" for electrochemical pre-lithiation increases the processing capacity by 5 to 10 times (can process kg-level slurry in a single batch), and reduces the volume of the pre-lithiation device by more than 60%, thereby reducing site occupation and equipment costs. 2. After pre-lithiation, the solid electrolyte and film-forming additives form a composite coating layer, protecting the active lithium from reacting with air / moisture. The environmental control requirements are reduced from -40~-50℃ to conventional nitrogen protection, and the process cost is reduced by 30%. 3. Uniform lithium replenishment and enhanced stability of silicon-based materials: synchronous stirring by the agitator and electrochemically controllable lithium replenishment result in a lithium replenishment uniformity deviation of ≤1% (compared to ≥5% for traditional lithium powder replenishment). Furthermore, the synergistic effect of the solid electrolyte (physical support) and film-forming additives (SEI film stability) ensures that even if the silicon lithium intercalation expands by 2-3 times, the coating layer remains intact, improving SEI film stability by 50% and reducing active lithium consumption by 40%. 4. Battery performance is significantly improved. The specific capacity of the prepared silicon-based negative electrode sheet can reach 385~935mAh / g, with an initial efficiency of 101~104.6%. The assembled soft-pack battery (model 508595, 5Ah) retains ≥94.4% capacity after 7 days of storage at 45℃ (compared to only 85~87% for the control group without solid electrolyte / film-forming additives), and retains ≥88% capacity after 1000 cycles. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart of the electrochemical pre-lithiation silicon-based anode slurry preparation method of the present invention; Figure 2This is a cross-sectional view of the electrochemical pre-lithiation device of the present invention; Figure 3 This is a top view of the electrochemical pre-lithiation device of the present invention.

[0019] Explanation of markings in the diagram: 1. Positive current collector; 2. Electrolyte layer; 3. Negative current collector; 4. Solid electrolyte membrane; 5. Stirring tank; 6. Second slurry. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0022] The following reference Figures 1 to 3 This invention describes a method for preparing an electrochemically pre-lithiated silicon-based anode slurry.

[0023] like Figures 1 to 3 As shown, a method for preparing an electrochemically pre-lithiated silicon-based anode slurry includes the following steps: S1: The solid electrolyte is ball-milled to obtain the first ball-milled slurry; Specifically, in step S1, during the ball milling process of the solid electrolyte, the solid electrolyte (or a mixture of solid electrolyte and dispersant) is ball milled to obtain a first ball mill slurry. The initial particle size of the solid electrolyte is 0.5~20μm, and the particle size after ball milling must be less than 100nm. The purpose is to improve the uniformity of the solid electrolyte's coating on the silicon-based material and enhance lithium-ion conductivity.

[0024] The optimal ball milling process parameters are: rotation speed of 1000~2500 r / min, time of 8~20 h; the dispersant is selected from one or a combination of ethylene carbonate (EC), propylene carbonate (PC), N,N-dimethylformamide (DMF), etc., and the amount of dispersant should be such that the solid electrolyte is uniformly dispersed and does not agglomerate.

[0025] S2: Add silicon-based material, graphite, conductive agent, binder, lithium salt and film-forming additive to the first ball milling slurry and stir to obtain the second slurry 6; Specifically, in step S2, when preparing the second slurry 6, the conductive agent is selected from one or a combination of carbon black conductive agent (SP), carbon nanotubes (CNT), graphene (GN), acetylene black, and conductive graphite KS-6; the binder is selected from one or a combination of polyurethane, polyacrylic acid, polyvinylidene fluoride, ABS resin, urea-formaldehyde resin, melamine-formaldehyde resin, epoxy resin, and unsaturated polyester resin, and the particle size range of the binder is 10~100nm; the graphite is selected from one or a combination of artificial graphite, natural graphite, and mesophase carbon microspheres, and the particle size is 5-30μm.

[0026] Preferably, the stirring process parameters are 10~50 r / min for revolution, 1000~3000 r / min for rotation, and 3~8 h for time, to ensure that the components are evenly dispersed and there is no obvious agglomeration.

[0027] S3: Pour the second slurry 6 into the electrochemical pre-lithiation device and perform electrochemical pre-lithiation on the second slurry 6 to obtain an electrochemically pre-lithiated silicon-based anode slurry.

[0028] Specifically, the pre-lithiation degree needs to be controlled to be 5-30% of the total theoretical capacity of the active material silicon-based material and graphite in the slurry. This is achieved by adjusting the pre-lithiation current and time. For example, when the total capacity of the active material is 310Ah, the current is controlled at 120A and the time at 12.4min, resulting in a lithium replenishment capacity of 24.8Ah, which corresponds to 8% of the total capacity.

[0029] Furthermore, such as Figure 2 and Figure 3 As shown, the electrochemical pre-lithiation device includes, from the outside in, an electrolyte layer 2, a negative electrode current collector layer 3, a solid electrolyte membrane 4, and a stirring tank 5 surrounded by the solid electrolyte membrane 4. A positive electrode current collector 1 is provided in the stirring tank 5. The positive electrode current collector 1 is a stirring paddle. The stirring paddle is used to stir the second slurry 6 in the stirring tank 5 so that the second slurry 6 can be electrochemically pre-lithiated.

[0030] Specifically, electrolyte layer 2 is a lithium metal-side electrolyte that soaks the negative electrode current collector 3 to provide a lithium-ion source; the negative electrode current collector 3 layer uses lithium metal sheets with a purity ≥99.95% and also serves as a lithium replenishment source, with a thickness of 0.1~0.2mm; the solid electrolyte membrane 4 is selected from LLZO-PE composite membranes, etc., with a thickness of 20~30μm, which can conduct lithium ions but isolates the solvent, preventing the electrolyte layer 2 from mixing with the slurry in the stirring tank 5; the stirring tank 5 contains a second slurry 6, and a positive electrode current collector 1 is set inside the tank. The positive electrode current collector 1 uses a planetary stirring paddle made of titanium alloy TA2 with a sandblasted surface. The stirring paddle rotates synchronously during the pre-lithiation process at a speed of 5~30r / min to ensure uniform lithium replenishment of the slurry; the annular tank containing the electrolyte layer 2 and the stirring tank 5 are both in a sealed nitrogen atmosphere, eliminating the need for strict oxygen-free / low dew point control.

[0031] Preferably, during the stirring process, the stirring speed is 10~50 r / min for revolution and 1000~3000 r / min for rotation, and the stirring time is 3~8 h.

[0032] Furthermore, the mass ratio of the silicon-based material, the solid electrolyte, the graphite, the film-forming additive, the lithium salt, the binder, and the conductive agent is 4~50:10~25:40~80:2~6:0.5~5:5~10:3~10.

[0033] Furthermore, the solid electrolyte uses Li 0.33 La 0.56 TiO3, Li7La3Zr2O 12 Li 1.4 Al 0.4 Ti 1.6 (PO4)3, Li4Ti5O 12 One or a combination of LiAlO2.

[0034] Furthermore, the initial particle size range of the solid electrolyte is 0.5~20μm, and the particle size of the solid electrolyte after ball milling is less than 100nm.

[0035] Furthermore, the silicon-based material is a silicon-carbon anode material, and the specific capacity of the silicon-carbon anode material is in the range of 450~1800mAh / g.

[0036] Furthermore, the degree of pre-lithiation of the electrochemically pre-lithiated silicon-based anode slurry is 5-30% of the total capacity of the active material in the electrochemically pre-lithiated silicon-based anode slurry.

[0037] Furthermore, the lithium salt is one or a combination of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorooxalate)borate, lithium perchlorate, and lithium chloride.

[0038] Furthermore, step S1 also includes the following step: simultaneously ball milling the solid electrolyte and the dispersant to obtain a first ball mill slurry.

[0039] Furthermore, the film-forming additive is one or a combination of citric acid, malic acid, ascorbic acid, fruit acid, sorbic acid, tartaric acid, vinylene carbonate, fluoroethylene carbonate, ethylene ethylene carbonate, and 1,3-propanesulfonyl lactone.

[0040] Furthermore, after obtaining the electrochemically pre-lithiated silicon-based anode slurry, the electrochemically pre-lithiated silicon-based anode slurry is coated and dried, and then subjected to a hot pressing process to obtain a pre-lithiated solid anode sheet.

[0041] Preferably, the temperature of the coating and drying process is 80~130℃, and the temperature of the hot pressing process is 80~150℃.

[0042] The present invention is further illustrated below through specific embodiments, but these embodiments do not limit the scope of protection of the present invention. The materials used in the embodiments are all commercially available conventional products, and the testing methods are conventional tests in the field of lithium-ion batteries (button half-cell test: charge and discharge voltage 0.005~2.0V; full-cell test: 508595 soft pack battery, charge and discharge current 1.65A, voltage 2.8~4.2V).

[0043] Example 1 130g of solid electrolyte LLTO (initial particle size 15μm) and 1000g of dispersant acetonitrile were added to mixing tank 5. The mixture was ball-milled at 2000 r / min for 15 h to obtain the first ball-milled slurry (LLTO particle size 21nm). Then, 100g of silicon-based material (specific capacity 650mAh / g, particle size 14μm), 700g of artificial graphite (particle size 15μm), and conductive agents CNT and SP were added to the first ball-milled slurry. 30g of silicon-based polymer (LLTO): 70g of polyurethane adhesive (particle size 30nm), 30g of lithium salt LiODFB, and 40g of film-forming additive FEC; stirring parameters: revolution at 25r / min, rotation at 3000r / min, stirring time 5h, to obtain the second slurry 6 (mass ratio of components: silicon-based: LLTO: graphite: FEC: LiODFB: polyurethane: conductive agent = 10:13:70:4:3:7:6); the second slurry 6 was poured into... Figure 2 and Figure 3 The device shown has a pre-lithiation capacity of 24.8 Ah, and the total active material capacity is 8% of 310 Ah. The lithium replenishment current is controlled at 120 A for 12.4 min. After pre-lithiation, the slurry is coated and dried at 100 °C and hot-pressed at 130 °C to obtain the electrode.

[0044] Performance testing: 385.2mAh / g coin cell capacity, 104.6% initial efficiency; 96.7% capacity retention after 7 days of storage at 45℃ with full charge.

[0045] Example 2 197g of solid electrolyte LAO with an initial particle size of 3μm and 2200g of dispersant DMC were ball-milled at 1500r / min for 20h. The first ball-milled slurry (LAO particle size 32nm) was then mixed with 400g of silicon-based material (specific capacity 1300mAh / g, particle size 8μm), 590g of artificial graphite (particle size 8μm), 52.5g each of conductive agents CNT and GN, 105g of binder polyacrylic acid (particle size 20nm), and lithium salt LiTFS. The composition of the slurry was 52g of I and 65.5g of the film-forming additive VEC; the stirring parameters were 30r / min for revolution and 3000r / min for rotation, and the stirring time was 5h; the mass ratio of each component was: silicon-based: LLTO: graphite: FEC: LiODFB: polyurethane: conductive agent = 30:15:45:5:4:8:8, the pre-lithiation capacity was 72.6Ah, the total capacity of the active material was 10% of 726Ah, the current was 200A, and the time was 22min; after pre-lithiation, the slurry was coated and dried at 100℃ and hot-pressed at 120℃ to obtain the electrode.

[0046] Performance testing: 716.4mAh / g coin cell capacity, 103.3% initial efficiency; 94.4% capacity retention after 7 days of storage at 45℃ with full charge.

[0047] Example 3 220g of solid electrolyte LATP with an initial particle size of 8μm and 1800g of dispersant DMF were added to mixing tank 5. The mixture was ball-milled at 1500 rpm for 20 hours, resulting in LATP particles with a particle size of 16nm. To the first ball-milled slurry, 600g of silicon-based material (with a specific capacity of 1600mAh / g and a particle size of 6μm), 495g of graphite (with a particle size of 5.5μm), 49.5g each of conductive agents CNT and SP, 99g of polyvinylidene fluoride (PVDF) (with a particle size of 50nm), and lithium salt were added. The sample weight was 44g, and 1,3-PS was 55g; the stirring parameters were 28r / min for revolution, 2800r / min for rotation, and 6h for stirring time; the mass ratio of each component was: silicon-based: LLTO: graphite: FEC: LiODFB: polyurethane: conductive agent = 45:20:45:5:4:9:9; the pre-lithiation capacity was 113Ah (10% of the total capacity of 1133Ah), the lithium replenishment current was controlled at 300A, and the lithium replenishment time was controlled at 22min; after pre-lithiation, the slurry was coated and dried at 110℃ and hot-pressed at 150℃; Performance testing: 935.2mAh / g coin cell capacity, 101.0% initial efficiency; 94.6% capacity retention after 7 days of storage at 45℃ with full charge.

[0048] Comparative Example 1 Except for the absence of FEC in step S2, the rest is the same as in Example 1; Test results: coin cell capacity 826.1mAh / g, first-time efficiency 91.2%; total battery retention rate 85.8%.

[0049] Comparative Example 2 Except for the absence of LLTO in step S1, the rest is the same as in Example 1; Test results: coin cell capacity 868.4 mAh / g, first-time efficiency 97.3%; total battery retention rate 87.2%.

[0050] To further investigate the stability of the negative electrode sheet after electrochemical pre-lithiation with solid electrolyte and film-forming additives, a full-electrode fabrication was conducted. The positive electrode used high-nickel 811 material, with a formulation of positive electrode material: conductive agent CNT: conductive agent SP: binder PVDF mass ratio of 96.5:0.5:1.5:1.5. A conventional PE separator and conventional electrolyte were used, and a stacking method was employed to fabricate a 508595 soft-pack battery with a rated capacity of 5Ah. After fabrication and three charge-discharge cycles, a 7-day high-temperature (45°C) stability test was conducted to examine capacity retention. The charge-discharge current was 1.65A, the upper limit voltage was 4.2V, the lower limit voltage was 2.8V, and the cutoff current was 0.25A. The test results are shown in Table 1. It can be seen that the battery with both solid electrolyte and film-forming additives exhibits higher capacity retention than the comparative example without film-forming additives or solid electrolyte modification.

[0051] Table 1. Comparison of Capacity Retention Rate Test after 7 Days of Fully Charged Storage at 45°C

[0052] As shown above, the total capacity retention rates of Examples 1-3 (94.4%-96.7%) are significantly higher than those of Comparative Example 1 (85.8%) and Comparative Example 2 (87.2%), demonstrating that the performance is not simply additive but rather a synergistic mechanism. The film-forming additives (such as FEC, VEC, and 1,3-PS) preferentially react during the pre-lithiation process, forming a LiF-rich layer. A stable SEI film can isolate the silicon-based material from direct contact with the electrolyte, preventing the electrolyte solvent (such as EC) from continuously decomposing and eroding the silicon substrate at high temperatures, thus reducing the consumption of active lithium. Film-forming additives form a chemically stable SEI film (inner layer). Ball-milled nanoscale solid electrolytes (LLTO, LAO, LATP, particle size ≤32nm) are uniformly coated on the silicon substrate surface. Their rigid structure can resist the volume expansion after lithium intercalation (even with an expansion of 2-3 times, the coating layer does not break), preventing the SEI film from being torn due to silicon expansion and maintaining interface integrity. The solid electrolyte forms a physically anti-expansion coating layer (outer layer). The inner SEI film isolates chemical erosion, while the outer coating layer resists physical expansion. The combination of these two technologies solves the core problems of easy SEI film breakage and easy silicon substrate exposure. Using either technology alone can only solve a single problem, such as SEI stability or anti-expansion, and cannot simultaneously ensure long-term cycle stability. Solid electrolytes, such as LLTO, have room temperature ionic conductivity... It can serve as an additional lithium-ion channel to compensate for the conductivity limitations of the SEI film. The ionic conductivity of the SEI film is... In Example 1, the LLTO coating layer and the SEI film form a series conduction path. Lithium ions first migrate rapidly through the LLTO to the SEI film and then enter the silicon substrate, avoiding ion conduction obstruction caused by an excessively thick SEI film. This is also the key reason why Example 1 can maintain high first-efficiency even at a high pre-lithiation degree (8%). In Comparative Example 1, the SEI film decomposes the products using an electrolyte solvent ( (Mainly) under high temperature Easily decomposed into and This leads to damage to the SEI film, further erosion of the silicon substrate by the electrolyte, and accelerated capacity decay. In Comparative Example 2, which does not have LLTO, lithium ions must pass through the SEI film alone, resulting in high conduction resistance. Some lithium cannot be embedded into the silicon substrate, leading to lower first-time efficiency. Comparative Example 2 relies solely on the SEI film formed by film-forming additives, which cannot resist the physical expansion of silicon. During storage, the SEI film cracks due to the slight expansion of silicon, triggering interfacial side reactions and reducing capacity retention.

[0053] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing an electrochemically pre-lithiated silicon-based anode slurry, characterized in that, Includes the following steps: S1: The solid electrolyte is ball-milled to obtain the first ball-milled slurry; S2: Add silicon-based material, graphite, conductive agent, binder, lithium salt and film-forming additive to the first ball milling slurry and stir to obtain a second slurry; S3: Pour the second slurry into the electrochemical pre-lithiation device and perform electrochemical pre-lithiation on the second slurry to obtain an electrochemically pre-lithiated silicon-based anode slurry.

2. The method for preparing electrochemically pre-lithiated silicon-based anode slurry according to claim 1, characterized in that, The electrochemical pre-lithiation device includes, from the outside in, an electrolyte layer, a negative electrode current collector layer, a solid electrolyte membrane, and a stirred tank surrounded by the solid electrolyte membrane. A positive electrode current collector is provided in the stirred tank. The positive electrode current collector is a stirring paddle. The stirring paddle is used to stir the second slurry in the stirred tank so that the second slurry can be electrochemically pre-lithiated.

3. The method for preparing electrochemically pre-lithiated silicon-based anode slurry according to claim 1, characterized in that, The mass ratio of the silicon-based material, the solid electrolyte, the graphite, the film-forming additive, the lithium salt, the binder, and the conductive agent is 4~50:10~25:40~80:2~6:0.5~5:5~10:3~10.

4. The method for preparing electrochemically pre-lithiated silicon-based anode slurry according to claim 1, characterized in that, The solid electrolyte uses Li 0.33 La 0.56 TiO3, Li7La3Zr2O 12 Li 1.4 Al 0.4 Ti 1.6 (PO4)3, Li4Ti5O 12 One or a combination of LiAlO2.

5. The method for preparing electrochemically pre-lithiated silicon-based anode slurry according to claim 1, characterized in that, The initial particle size range of the solid electrolyte is 0.5~20μm, and the particle size of the solid electrolyte after ball milling is less than 100nm.

6. The method for preparing electrochemically pre-lithiated silicon-based anode slurry according to claim 1, characterized in that, The silicon-based material is a silicon-carbon anode material, and the specific capacity of the silicon-carbon anode material is in the range of 450~1800mAh / g.

7. The method for preparing electrochemically pre-lithiated silicon-based anode slurry according to claim 1, characterized in that, The degree of pre-lithiation of the electrochemically pre-lithiated silicon-based anode slurry is 5-30% of the total capacity of the active material in the electrochemically pre-lithiated silicon-based anode slurry.

8. The method for preparing electrochemically pre-lithiated silicon-based anode slurry according to claim 1, characterized in that, The lithium salt is one or a combination of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethyl)sulfonylimide, lithium bis(fluorooxalate)borate, lithium perchlorate, and lithium chloride.

9. The method for preparing electrochemically pre-lithiated silicon-based anode slurry according to claim 1, characterized in that, Step S1 also includes the following step: simultaneously ball milling the solid electrolyte and the dispersant to obtain a first ball mill slurry.

10. The method for preparing electrochemically pre-lithiated silicon-based anode slurry according to claim 1, characterized in that, The film-forming additive is one or a combination of citric acid, malic acid, ascorbic acid, fruit acid, sorbic acid, tartaric acid, vinylene carbonate, fluoroethylene carbonate, ethylene ethylene carbonate, and 1,3-propanesulfonyl lactone.

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