Method for repairing solid electrolyte interface layer of silicon negative electrode in slow-release manner

Abstract

The invention discloses a method for repairing a solid electrolyte interface layer of a silicon negative electrode in a slow release manner, and aims to solve the problems of poor electrochemical performance and short cycle life of the silicon negative electrode of the existing lithium ion battery. The preparation method comprises the following steps: mixing a sodium carboxymethyl cellulose aqueous solution and a styrene butadiene rubber dispersion liquid to obtain a binder system; 2, mixing the silicon particles with conductive carbon to obtain silicon-carbon mixed powder; 3, mixing the silicon-carbon mixed powder with a binder system; 4, adding HOTU into the precursor slurry, and uniformly mixing to obtain silicon negative electrode slurry; and 5, coating a copper foil with the silicon negative electrode slurry, and carrying out curing treatment at the temperature of 40-100 DEG C. The obtained slow-release repair system can repair a solid electrolyte interface layer for a long time, low interface impedance, high lithium ion diffusion coefficient and long cycle life are achieved, the capacity retention rate is 77.80% after 1000 cycles, and meanwhile the method is simple in process, low in raw material cost and suitable for large-scale popularization.

Description

Technical Field

[0001] The present invention belongs to the field of lithium-ion battery silicon negative electrodes, and in particular relates to a method for slowly releasing a repairing silicon negative electrode solid electrolyte interface layer. Background Art

[0002] With the urgent need for efficient energy storage in modern society, electrochemical energy storage technology is becoming a key force driving scientific and technological progress. In many application areas, from electric vehicles and 3C electronic products to load regulation of smart grids, stable operation of power systems, and artificial satellites and lunar rovers in the aerospace field, energy storage solutions have always been the core bottleneck restricting system performance. As a core component, batteries directly determine the core performance indicators of energy storage systems, such as capacity, power output efficiency and cycle life. Although the technology of the currently widely used graphite negative electrode lithium-ion batteries continues to advance, its performance has approached the theoretical limit (372 mAh g -1 ), which has prompted people to explore battery systems with higher capacity. Silicon anode has an ultra-high specific capacity (3579 mAh g -1 , corresponding to Li 15 Si4), has become one of the negative electrode materials with the highest specific capacity. However, silicon negative electrodes face many challenges. During the lithiation and delithiation processes, they will produce a huge volume change of up to 300%, resulting in detachment from the conductive network and loss of activity during the cycle. In addition, its electrical conductivity and ionic conductivity are much lower than those of graphite negative electrodes (about 10 -5 S cm -1 and 10 -14 to 10 -13 cm 2 s -1 , while the graphite negative electrode is 10 to 10 4 Scm -1 and 10 -9 cm² s -1 These problems seriously hinder the practical application of silicon anodes, and innovative strategies are urgently needed to enhance their structural stability and electrochemical performance.

[0003] To solve the above problems, researchers have proposed a variety of strategies. For example, Liu et al. (Nat. Nanotechnol, 2014, 9, 187-192) were inspired by the structure of pomegranate and prepared a pomegranate-like silicon particle structure with better performance and higher tap density. Zhang et al. (ACS Appl. Mater. Interfaces, 2018, 10, 34283-34290) used silica as a sacrificial template, spray-dried and then carbonized at high temperature, combining the advantages of egg yolk shell and porous structure to prepare a porous silicon-carbon composite with a granite structure. Du et al. (Adv. Funct. Mater., 2021, 31, 9) used 3-aminopropyltriethoxysilane and dialdehyde molecules as silicon sources and carbon sources, and terephthalaldehyde, glutaraldehyde and glyoxal as crosslinking agents to construct SiO x / C hollow particles, and a series of polymer hollow spheres were obtained. These studies provide a reference for the design of new silicon anode systems, but the synthesis process is often too complicated and the performance needs to be improved.

[0004] Sustained-release agents are common in the pharmaceutical field, as they release drugs over a prolonged period to exert therapeutic effects. Similar sustained-release effects have been reported in gel polymer electrolytes (Adv. Funct. Mater., 2025, 35, 10), where the addition of lithium oxide enhances their long-term efficacy. However, there is little research on sustained-release systems for silicon anode applications. Summary of the Invention

[0005] The present invention aims to solve the problems of poor electrochemical performance and short cycle life of silicon negative electrodes in existing lithium-ion batteries, and provides a slow-release method for repairing the solid electrolyte interface layer of the silicon negative electrode.

[0006] The method for repairing the interface layer of the silicon negative electrode solid electrolyte by sustained-release method of the present invention is implemented by the following steps:

[0007] 1. Preparation of binder system:

[0008] The sodium carboxymethyl cellulose aqueous solution and the styrene-butadiene rubber dispersion are mixed and stirred to obtain a binder system, wherein the mass ratio of the sodium carboxymethyl cellulose to the styrene-butadiene rubber is 2:(1-5);

[0009] 2. Preparation of silicon-carbon mixed powder:

[0010] Silicon particles and conductive carbon are mixed in a mass ratio of 8:(0.5-3), and then ground to obtain silicon-carbon mixed powder;

[0011] 3. Preparation of precursor slurry:

[0012] The silicon-carbon mixed powder and the binder system are mixed in a mass ratio of 9:(0.5-3), and the mixture is stirred evenly to obtain a precursor slurry;

[0013] 4. Addition of sustained-release additives:

[0014] According to the mass ratio of silicon particles to HOTU (O-[(ethoxycarbonyl) cyanomethylamine]-N,N,N',N'-tetramethylthiourea hexafluorophosphate) of 9.5:(2-15), HOTU is added to the precursor slurry and mixed until uniformly mixed to obtain a silicon negative electrode slurry;

[0015] 5. Silicon anode slurry coating:

[0016] The silicon negative electrode slurry is coated on the copper foil and cured at a temperature of 40°C to 100°C to obtain a silicon negative electrode pole piece, thereby completing the method of slow-release repair of the silicon negative electrode solid electrolyte interface layer.

[0017] The present invention first obtains a silicon anode slurry by grinding and stirring, and then coats and dries it to obtain a silicon anode pole piece. The slow-release repaired silicon anode solid electrolyte interface layer silicon anode system obtained by the present invention has excellent electrochemical performance and cycle performance.

[0018] The present invention proposes a binder system for silicon negative electrodes, which can quickly repair damaged solid electrolyte interface layers over a long period of time. By introducing HOTU containing hexafluorophosphate anion groups and nitrogen-containing cationic groups, continuous in-situ repair of the solid electrolyte interface layer during the cycle is achieved, generating a large amount of lithium nitride, and enhancing the stability of the silicon negative electrode. The charged groups in HOTU also enhance the electrochemical properties of the silicon negative electrode through electrostatic effects, achieving low interfacial impedance, high lithium ion diffusion coefficient, and long cycle life. So far, there has been no report on the use of HOTU as an additive for lithium-ion battery silicon negative electrodes to achieve long-term sustained-release repair of the solid electrolyte interface layer. This method has a simple process, cheap raw materials, and is suitable for large-scale promotion.

[0019] The method for repairing the silicon negative electrode solid electrolyte interface layer by slow-release method of the present invention has the following beneficial effects:

[0020] 1. The synthesis process of the present invention is very simple and can be achieved by simply adding HOTU during the preparation of silicon negative electrode slurry;

[0021] 2. The sustained-release repaired silicon negative electrode solid electrolyte interface layer silicon negative electrode system obtained by the present invention has low interface impedance and high lithium ion diffusion coefficient, which greatly improves the inherent low lithium ion conductivity and low electronic conductivity of silicon element.

[0022] 3. The sustained-release repaired silicon negative electrode solid electrolyte interface layer silicon negative electrode system obtained by the present invention still has good structural integrity after experiencing repeated volume changes.

[0023] 4. The sustained-release repaired silicon negative electrode solid electrolyte interface layer silicon negative electrode system obtained by the present invention has an extremely long cycle life. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a long cycle test result diagram of the slow-release repaired silicon anode solid electrolyte interface layer silicon anode system prepared in Example 1 with different HOTU addition amounts;

[0025] Figure 2 This is an electron scanning microscope image of the silicon negative electrode system of the slow-release repaired silicon negative electrode solid electrolyte interface layer prepared in Example 1 with different HOTU addition amounts;

[0026] Figure 3 This is an electron scanning microscope image of the slow-release repaired silicon anode solid electrolyte interface layer silicon anode system prepared in Example 1 with different HOTU addition amounts after 50 cycles;

[0027] Figure 4 This is the electrochemical impedance spectroscopy test graph of the slow-release repaired silicon anode solid electrolyte interface layer silicon anode system prepared in Example 1 with different HOTU addition amounts after 10 cycles;

[0028] Figure 5 Cyclic voltammetry test diagram of the sustained-release repaired silicon anode solid electrolyte interface layer silicon anode system at different scan rates with different HOTU addition amounts prepared in Example 1;

[0029] Figure 6 This is the N 1s peak X-ray photoelectron spectroscopy etching test diagram of the Si@H4 sample of the silicon negative electrode system with slow-release repaired silicon negative electrode solid electrolyte interface layer prepared in Example 1 with different HOTU addition amounts. DETAILED DESCRIPTION

[0030] Specific embodiment 1: The method for repairing the silicon negative electrode solid electrolyte interface layer by sustained-release method in this embodiment is implemented by the following steps:

[0031] 1. Preparation of binder system:

[0032] The sodium carboxymethyl cellulose aqueous solution and the styrene-butadiene rubber dispersion are mixed and stirred to obtain a binder system, wherein the mass ratio of the sodium carboxymethyl cellulose to the styrene-butadiene rubber is 2:(1-5);

[0033] 2. Preparation of silicon-carbon mixed powder:

[0034] Silicon particles and conductive carbon are mixed in a mass ratio of 8:(0.5-3), and then ground to obtain silicon-carbon mixed powder;

[0035] 3. Preparation of precursor slurry:

[0036] The silicon-carbon mixed powder and the binder system are mixed in a mass ratio of 9:(0.5-3), and the mixture is stirred evenly to obtain a precursor slurry;

[0037] 4. Addition of sustained-release additives:

[0038] According to the mass ratio of silicon particles to HOTU (O-[(ethoxycarbonyl) cyanomethylamine]-N,N,N',N'-tetramethylthiourea hexafluorophosphate) of 9.5:(2-15), HOTU is added to the precursor slurry and mixed until uniformly mixed to obtain a silicon negative electrode slurry;

[0039] 5. Silicon anode slurry coating:

[0040] The silicon negative electrode slurry is coated on the copper foil and cured at a temperature of 40°C to 100°C to obtain a silicon negative electrode pole piece, thereby completing the method of slow-release repair of the silicon negative electrode solid electrolyte interface layer.

[0041] This embodiment uses sodium carboxymethyl cellulose with a degree of substitution of 0.5 to 1.2 as a binder, so that the sodium carboxymethyl cellulose has more suitable solubility and thickening effect, and achieves the best bonding effect in combination with the addition amount of HOTU.

[0042] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that the mass ratio of water to sodium carboxymethyl cellulose in the sodium carboxymethyl cellulose aqueous solution in step 1 is 100:(1~4).

[0043] Specific embodiment three: This embodiment differs from specific embodiment one or two in that the mixing and stirring time in step one is 10 to 20 hours.

[0044] Specific embodiment 4: This embodiment differs from any one of specific embodiments 1 to 3 in that the grinding treatment time in step 2 is 0.5 to 5 hours.

[0045] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the diameter of the silicon particles in step 2 is 50 nanometers to 5 micrometers.

[0046] Specific embodiment six: This embodiment differs from any one of specific embodiments one to five in that the conductive carbon in step two is a mixture of one or more of conductive carbon black, carbon fibers, graphites, graphenes, carbon black, pyrolytic carbon, activated carbon, and carbon quantum dots.

[0047] Specific embodiment seven: This embodiment differs from any one of specific embodiments one to six in that in step three, the silicon-carbon mixed powder is mixed with the binder system in a mass ratio of 9:(1-1.5).

[0048] Specific embodiment eight: This embodiment differs from specific embodiments one to seven in that in step four, HOTU is added to the precursor slurry for mixing at a mass ratio of silicon particles to HOTU of 9.5:(6-12).

[0049] Specific embodiment nine: The difference between this embodiment and any one of specific embodiments one to eight is that the mixing method in step four adopts stirring mixing, ultrasonic mixing, grinding mixing, oscillation mixing, high-pressure homogenization mixing, electrostatic mixing, spray mixing, emulsification mixing, adsorption mixing, sedimentation mixing or immersion mixing.

[0050] Specific embodiment ten: This embodiment differs from specific embodiments one to nine in that in step five, the silicon negative electrode slurry is coated on the copper foil with a coating thickness of 100 nanometers to 10 micrometers.

[0051] Specific embodiment 11: The difference between this embodiment and specific embodiments 1 to 10 is that the curing treatment in step 5 is to dry at a temperature of 40°C to 100°C for 4 to 20 hours.

[0052] The drying method in this embodiment may also be one of vacuum drying, convection drying, conduction drying, radiation drying, dielectric heating drying, microwave drying, ultrasonic drying, filtration drying, compressed air drying, and adsorption drying.

[0053] Example 1: The method for repairing the silicon negative electrode solid electrolyte interface layer by sustained-release method in this embodiment is implemented by the following steps:

[0054] 1. Preparation of binder system:

[0055] A sodium carboxymethyl cellulose aqueous solution with a degree of substitution of 0.6 and a styrene-butadiene rubber dispersion were mixed and magnetically stirred at 30° C. for 10 hours to obtain a binder system;

[0056] The mass ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 2:3;

[0057] 2. Preparation of silicon-carbon mixed powder:

[0058] Silicon particles and conductive carbon black were mixed in a mass ratio of 8:1, and then ground for 1 hour to obtain a silicon-carbon mixed powder;

[0059] 3. Preparation of precursor slurry:

[0060] The silicon-carbon mixed powder and the binder system were mixed in a mass ratio of 9:1 and magnetically stirred at 30° C. for 10 hours to obtain a precursor slurry;

[0061] 4. Addition of sustained-release additives:

[0062] HOTU was added to the precursor slurry at a mass ratio of silicon particles to HOTU of 8:2, and the mixture was magnetically stirred at 30°C for 10 hours to obtain a silicon anode slurry;

[0063] 5. Silicon anode slurry coating:

[0064] Use a scraper to coat the silicon negative electrode slurry on the copper foil with a coating thickness of 0.5 microns, and dry it in a vacuum oven at 60°C for 8 hours to obtain a silicon negative electrode sheet recorded as Si@H2, thereby completing the method of slow-release repair of the silicon negative electrode solid electrolyte interface layer.

[0065] Example 2: The method for repairing the silicon negative electrode solid electrolyte interface layer by sustained-release method in this embodiment is implemented by the following steps:

[0066] 1. Preparation of binder system:

[0067] A sodium carboxymethyl cellulose aqueous solution with a degree of substitution of 0.6 and a styrene-butadiene rubber dispersion were mixed and magnetically stirred at 30° C. for 10 hours to obtain a binder system;

[0068] The mass ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 2:3;

[0069] 2. Preparation of silicon-carbon mixed powder:

[0070] Silicon particles and conductive carbon black were mixed in a mass ratio of 8:1, and then ground for 1 hour to obtain a silicon-carbon mixed powder;

[0071] 3. Preparation of precursor slurry:

[0072] The silicon-carbon mixed powder and the binder system were mixed in a mass ratio of 9:1 and magnetically stirred at 30° C. for 10 hours to obtain a precursor slurry;

[0073] 4. Addition of sustained-release additives:

[0074] HOTU was added to the precursor slurry at a mass ratio of silicon particles to HOTU of 6:4, and the mixture was magnetically stirred at 30°C for 10 hours to obtain a silicon anode slurry;

[0075] 5. Silicon anode slurry coating:

[0076] Use a scraper to coat the silicon negative electrode slurry on the copper foil with a coating thickness of 0.5 microns, and dry it in a vacuum oven at 60°C for 8 hours to obtain a silicon negative electrode sheet recorded as Si@H4, thereby completing the method of slow-release repair of the silicon negative electrode solid electrolyte interface layer.

[0077] Example 3: The method for repairing the silicon negative electrode solid electrolyte interface layer by sustained-release method in this embodiment is implemented by the following steps:

[0078] 1. Preparation of binder system:

[0079] A sodium carboxymethyl cellulose aqueous solution with a degree of substitution of 0.6 and a styrene-butadiene rubber dispersion were mixed and magnetically stirred at 30° C. for 10 hours to obtain a binder system;

[0080] The mass ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 2:3;

[0081] 2. Preparation of silicon-carbon mixed powder:

[0082] Silicon particles and conductive carbon black were mixed in a mass ratio of 8:1, and then ground for 1 hour to obtain a silicon-carbon mixed powder;

[0083] 3. Preparation of precursor slurry:

[0084] The silicon-carbon mixed powder and the binder system were mixed in a mass ratio of 9:1 and magnetically stirred at 30° C. for 10 hours to obtain a precursor slurry;

[0085] 4. Addition of sustained-release additives:

[0086] HOTU was added to the precursor slurry at a mass ratio of silicon particles to HOTU of 4:6, and the mixture was magnetically stirred at 30°C for 10 hours to obtain a silicon anode slurry;

[0087] 5. Silicon anode slurry coating:

[0088] The silicon negative electrode slurry was coated on the copper foil using a scraper with a coating thickness of 0.5 μm, and dried in a vacuum oven at 60°C for 8 hours to obtain a silicon negative electrode sheet denoted as Si@H6, thereby completing the method of slow-release repair of the silicon negative electrode solid electrolyte interface layer.

[0089] Figure 1 These are the constant current charge and discharge test results for silicon||lithium iron phosphate batteries. The electrolyte consisted of 1 mol / L lithium hexafluorophosphate dissolved in a 1:1 volume ratio of ethylene carbonate and dimethyl carbonate, with 5 wt% fluoroethylene carbonate added as an additive. The tests were conducted using the Shenzhen Xinweier Battery Testing System. Figure 2 and Figure 3 The results are from a scanning electron microscope, using a Zeiss Gemini 560 device. Figure 4 The electrochemical impedance spectroscopy data were tested using Chenhua CHI760e equipment. Figure 5 This is the b-value calculation result, tested using Chenhua CHI760e equipment; Figure 6 These are the results of X-ray photoelectron spectroscopy tests, using the Thermo Fisher ESCALAB 250Xi equipment.

[0090] Figure 1 The long-term cycling results of the silicon anode system with a sustained-release repaired silicon anode solid electrolyte interface layer prepared in Examples 1 to 3, using a silicon||lithium iron phosphate battery system and a current of 5 C, are shown. The unimproved sample decayed to 0 mAh / g within 100 cycles. The improved batteries exhibited different cycle lives due to the different HOTU addition amounts. Among them, Si@H4 exhibited the best performance, with a capacity retention rate of 77.80% after 1000 cycles.

[0091] Figure 2 Scanning electron microscopy results of the silicon anode systems with different HOTU addition amounts and sustained-release repaired silicon anode solid electrolyte interface layers prepared in Examples 1 and 2. The silicon particles in the unrepaired samples are loose and have a low degree of aggregation. The silicon in Si@H4 is highly aggregated and bonded into large clusters.

[0092] Figure 3 Scanning electron microscopy images of the silicon anode systems with different HOTU addition levels after 50 cycles show that the untreated samples exhibited severe surface cracking and silicon particles became dusty. The Si@H4 sample showed no cracking, and the silicon particles remained firmly bonded.

[0093] Figure 4 The electrochemical impedance spectroscopy test results of the slow-release repaired silicon negative electrode solid electrolyte interface layer silicon negative electrode system with different HOTU addition amounts prepared in Examples 1 to 3 after 10 cycles are shown in Table 1. The solid electrolyte layer impedance and electron transfer resistance impedance of the unimproved sample are much greater than those after improvement. After adding HOTU, the solid electrolyte layer impedance and electron transfer resistance impedance are significantly reduced, as shown in Table 1 below.

[0094] Table 1

[0095]

[0096] Figure 5 The b-values ​​are calculated from the cyclic voltammetry test results of the sustained-release repaired silicon negative electrode solid electrolyte interface layer silicon negative electrode system with different HOTU addition amounts prepared in Examples 1 to 3 at different scan rates. The b-values ​​of the unimproved samples are much smaller than those of the improved samples, showing poor electrochemical performance.

[0097] Figure 6 The N 1s peak X-ray photoelectron spectroscopy etching test results of the Si@H4 sample of the silicon negative electrode system with slow-release repaired silicon negative electrode solid electrolyte interface layer prepared in Example 2 with different HOTU addition amounts show that the content of lithium nitride increases with the increase of etching depth, indicating that there is a large amount of lithium nitride in the solid electrolyte membrane, which is conducive to the stability of the silicon negative electrode.

[0098] The above results show that the electrochemical performance, cycle performance and structural stability of the sustained-release repaired silicon negative electrode solid electrolyte interface layer developed by the present invention have the advantages of low interface impedance, high lithium ion diffusion coefficient, long cycle life, good structural integrity and simple manufacturing process compared with the existing silicon negative electrode protection scheme.

[0099] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for repairing the interface layer of a silicon negative electrode solid electrolyte by slow release, characterized in that The method for repairing the silicon negative electrode solid electrolyte interface layer by slow-release method is implemented by the following steps:

1. Preparation of binder system: The sodium carboxymethyl cellulose aqueous solution and the styrene-butadiene rubber dispersion are mixed and stirred to obtain a binder system, wherein the mass ratio of the sodium carboxymethyl cellulose to the styrene-butadiene rubber is 2:(1-5); 2. Preparation of silicon-carbon mixed powder: Silicon particles and conductive carbon are mixed in a mass ratio of 8:(0.5-3), and then ground to obtain silicon-carbon mixed powder; 3. Preparation of precursor slurry: The silicon-carbon mixed powder and the binder system are mixed in a mass ratio of 9:(0.5-3), and the mixture is stirred evenly to obtain a precursor slurry; 4. Addition of sustained-release additives: HOTU is added to the precursor slurry at a mass ratio of silicon particles to HOTU of 9.5:(2-15) and mixed until uniformly mixed to obtain a silicon negative electrode slurry; 5. Silicon anode slurry coating: The silicon negative electrode slurry is coated on the copper foil and cured at a temperature of 40°C to 100°C to obtain a silicon negative electrode pole piece, thereby completing the method of slow-release repair of the silicon negative electrode solid electrolyte interface layer.

2. The method for repairing the interface layer of the silicon negative electrode solid electrolyte according to claim 1, characterized in that The mixing and stirring time in step 1 is 10 to 20 hours.

3. The method for repairing the interface layer of the silicon negative electrode solid electrolyte according to claim 1, characterized in that The grinding treatment time in step 2 is 0.5 to 5 hours.

4. The method for repairing the interface layer of the silicon negative electrode solid electrolyte according to claim 1, characterized in that The diameter of the silicon particles in step 2 is 50 nanometers to 5 micrometers.

5. The method for repairing the interface layer of the silicon negative electrode solid electrolyte according to claim 1, characterized in that The conductive carbon in step 2 is one or more mixtures of conductive carbon black, carbon fibers, graphites, graphenes, carbon black, pyrolytic carbon, activated carbon, and carbon quantum dots.

6. The method for repairing the interface layer of the silicon negative electrode solid electrolyte according to claim 1, characterized in that In step 3, the silicon-carbon mixed powder is mixed with the binder system in a mass ratio of 9:(1-1.5).

7. The method for repairing the interface layer of the silicon negative electrode solid electrolyte according to claim 1, characterized in that In step 4, HOTU is added to the precursor slurry and mixed according to the mass ratio of silicon particles to HOTU of 9.5: (6~12).

8. The method for repairing the interface layer of the silicon negative electrode solid electrolyte according to claim 1, characterized in that The mixing method in step 4 is stirring mixing, ultrasonic mixing, grinding mixing, oscillation mixing, high-pressure homogenization mixing, electrostatic mixing, spray mixing, emulsification mixing, adsorption mixing, sedimentation mixing or immersion mixing.

9. The method for repairing the interface layer of the silicon negative electrode solid electrolyte according to claim 1, characterized in that In step five, the silicon negative electrode slurry is coated on the copper foil with a coating thickness of 100 nanometers to 10 micrometers.

10. The method for repairing the interface layer of the silicon negative electrode solid electrolyte according to claim 1, characterized in that The curing treatment in step 5 is drying at a temperature of 40°C to 100°C for 4 to 20 hours.

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