Ultrathin copper current collector pretreatment method and application of ultrathin copper current collector pretreatment method in silicon-based negative electrode lithium battery

Abstract

The invention belongs to the technical field of new energy storage materials, and particularly relates to a pretreatment method of an ultrathin copper current collector and application of the ultrathin copper current collector in a silicon-based negative electrode lithium battery. The invention provides a pretreatment method of an ultrathin copper current collector, which comprises the following steps: carrying out acid pickling and activating treatment on a copper foil, then soaking the copper foil in a silane coupling agent hydrolysate, draining and curing to form an interface layer on the surface of the copper foil. The interface layer and a negative electrode binder generate strong ionic bonds through amino functional groups, the interface bonding force is remarkably enhanced, meanwhile, a flexible organic chain segment of the silane molecular layer can dynamically absorb shear stress generated by silicon expansion, and mechanical stripping of an active layer and a current collector is effectively inhibited. Polarization aggravation and capacity attenuation caused by stripping of an active material from the surface of a current collector due to high volume expansion of a traditional silicon-based negative electrode are avoided. According to the pretreatment method of the ultrathin copper current collector, the stable current collector is provided for the silicon-based negative electrode lithium battery, and the long circulation stability and the electrochemical performance of the silicon-based negative electrode lithium battery are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy storage materials, and particularly relates to a pretreatment method of an ultrathin copper current collector and application thereof in a silicon-based negative electrode lithium battery. BACKGROUND

[0002] With the increasing demand for high energy density batteries in electric vehicles and portable electronic devices, silicon-based negative electrode materials have become a research hotspot due to their theoretical capacity (about 4200 mAh / g). However, silicon will undergo severe volume change (expansion rate up to 300%) during charging and discharging, and the stress generated by repeated expansion and contraction will destroy the binding interface between the negative electrode coating and the copper current collector, resulting in the detachment of active materials from the surface of the copper foil and the fracture of the conductive network. After the active material is detached, it cannot participate in the electrochemical reaction, and the actual capacity of the battery rapidly decreases. Meanwhile, the accumulation of detached active material may pierce the separator and cause internal short circuit.

[0003] The current industry mainly alleviates this problem through two types of technologies: one is negative electrode material structure design, such as preparation of nano-silicon, porous silicon or silicon-carbon composite materials, to reduce stress by reserving expansion space. However, this method is complex and costly, and the nano-particles are prone to agglomeration, which cannot fundamentally solve the interface detachment problem. The other is to optimize the binder system, and to replace the traditional PVDF with strong adhesive polymers such as polyacrylic acid (PAA) and sodium alginate. However, the elasticity of the binder alone is still insufficient to resist the shear stress of long-term cycling, especially when the silicon content is >20%, the cracking and detachment rate of the electrode sheet is still high.

[0004] On the other hand, to improve the energy density of the battery, ultrathin copper foil (≤6 μm) is rapidly popularized, which further amplifies the interface challenge: 1. Mechanical strength drops sharply: with the thinning of the copper foil, the tensile strength decreases, which is more easily torn by the silicon expansion stress; 2. Surface coated with carbon layer: although the carbon layer can buffer stress, it is physically combined with the copper foil, which is prone to delamination after high-rate cycling, and increases the manufacturing cost; 3. Electroless nickel / copper plating: the metal plating layer can improve the interface conductivity, but the weight increase leads to a decrease in energy density, and the plating layer may be corroded in the electrolyte.

[0005] Therefore, it is urgent to develop a low-cost and easily mass-produced copper current collector interface strengthening technology to construct a stable and combined "rigid and flexible" interface layer at the molecular level, and fundamentally solve the detachment problem caused by silicon expansion. This is the core starting point of the present patent technology. SUMMARY

[0006] To overcome the above-mentioned deficiencies of the prior art, the present application provides a pretreatment method for ultra-thin copper current collector and its application in silicon-based negative electrode lithium battery. The present application proposes a pretreatment method for ultra-thin copper current collector, which includes acid washing and activation of copper foil, then dipping in silane coupling agent hydrolysis solution, and solidifying after draining to form an interface layer on the surface of copper foil. The interface layer forms strong ionic bonds with the negative electrode binder through amino functional groups, significantly enhancing the interfacial bonding force. Meanwhile, the flexible organic segments of the silane molecular layer can dynamically absorb the shear stress generated by silicon expansion, effectively inhibiting the mechanical peeling of the active layer from the current collector. The present application avoids the high volume expansion of the traditional silicon-based negative electrode, which causes the active material to peel off from the surface of the current collector, leading to polarization exacerbation and capacity decay. The pretreatment method for ultra-thin copper current collector proposed by the present application provides a stable current collector for silicon-based negative electrode battery, significantly improving the long cycle stability and electrochemical performance of silicon-based negative electrode lithium battery.

[0007] To achieve the above-mentioned purposes, the technical solution of the present application is as follows: a pretreatment method for ultra-thin copper current collector, comprising the following steps: The ultra-thin copper current collector is ultrasonically washed with phosphoric acid, acetone, and ethanol for 5 minutes to remove surface oxides and oils, and then subjected to acid washing and activation. The activated copper is immersed in a silane hydrolysis solution, the copper foil is taken out and drained, and then solidified at a temperature of 100-150°C for 5-30 minutes to form a covalently bonded Si-O-Cu interface layer on the surface of the copper foil. The interface layer forms strong ionic bonds with the negative electrode binder through amino functional groups, significantly enhancing the interfacial bonding force. Finally, a pretreated ultra-thin copper foil current collector is obtained.

[0008] Preferably, the ultra-thin copper current collector uses a copper foil with a thickness of 3-6 µm.

[0009] Preferably, the acid washing and activation uses at least one of a sulfuric acid, hydrochloric acid, or citric acid solution with a concentration of 5-10 vol%, and the treatment time is 30S-120S.

[0010] Preferably, the solidification process is carried out in an inert atmosphere or vacuum environment.

[0011] Preferably, the silane coupling agent is at least one of vinyl silane, amino silane, epoxy silane, or mercapto silane.

[0012] A modified copper current collector is prepared by the above-mentioned preparation method, which has an organic functional group layer covalently connected to its surface through a silicon-oxygen bond (Si-O-Cu), and the functional groups include amino (-NH2), epoxy, or mercapto (-SH).

[0013] A silicon-based negative electrode lithium battery is assembled from the above-mentioned modified copper current collector, as well as a silicon-based negative electrode sheet, a positive electrode, and a liquid electrolyte.

[0014] Preferably, the silicon-based negative electrode sheet includes the modified copper current collector described above, and a negative electrode active layer coated on its surface; the negative electrode active layer comprises a silicon-based material, conductive carbon, and a binder.

[0015] Preferably, the silicon-based material accounts for ≥70% of the mass of the active layer, and the adhesive comprises polyacrylic acid (PAA), sodium alginate, carboxymethyl cellulose, styrene-butadiene rubber, or polyimide.

[0016] Preferably, the silicon-based material is at least one of silicon-carbon material, silicon-oxygen material, and silicon material.

[0017] Compared with related technologies, the present invention has the following beneficial effects: 1. The pretreatment method for ultrathin copper current collectors proposed in this invention includes acid washing and activation of copper foil, followed by immersion in a silane coupling agent hydrolysate, followed by drying and curing to form an interface layer on the copper foil surface. A Si-O-Cu covalent bond interface layer is constructed on the copper foil surface using a silane coupling agent. The exposed amino (-NH2) functional groups form strong ionic / amide bonds with binders such as polyacrylic acid (PAA), thereby improving the interfacial adhesion of the ultrathin copper foil (3-6 μm) and completely solving the problem of active layer detachment caused by silicon expansion.

[0018] This invention innovatively uses a silane coupling agent to form an interface layer on the surface of copper foil, which allows the copper current collector to be in close contact with the silicon-based material layer. The flexible carbon chain structure of the silane layer can dynamically absorb the shear stress generated by silicon expansion. Combined with the dynamic bond reversible breakage-recombination mechanism, the peak shear stress is reduced, avoiding electrode cracking and causing the silicon-based active material layer to fall off after cycling, thus significantly improving the long-cycle stability of silicon-based anode batteries.

[0019] A variety of silicon-based active materials can be used in this invention, such as silicon-carbon materials, silicon materials, and silicon-oxygen materials, to meet different energy density requirements. At the same time, the thickness of the copper foil used in this invention can also be flexibly selected to meet the needs of laboratory pilot-scale testing and large-scale production, as well as the development needs of solid-state batteries in multiple scenarios.

[0020] In the pre-treated ultrathin copper current collector of the present invention, the silicon-based active material layer and the ultrathin copper current collector form a tight interface, and molecular bonding replaces physical anchoring, effectively optimizing the problem of poor physical contact between the traditional copper current collector and the silicon-based material layer. The cycle stability is significantly better than that of the traditional silicon-based anode battery system, and the long cycle stability of the silicon-based anode battery is improved to a stable 200 cycles with 85% capacity retention. Attached Figure Description

[0021] Figure 1The cycling performance diagrams of the solid-state batteries prepared by the pre-lithiated silicon-carbon anode and the non-pre-lithiated silicon-carbon anode combined with Ni85 cathode in Example 1 and Comparative Example 1 of the present invention are shown, wherein the activation rate is 0.1C, the cycling rate is 0.5C, and the cathode loading is 7mg / cm-2. (a) Example 1; (b) Comparative Example 1; Figure 2 The first-efficiency bar charts are shown for the positive electrode cells corresponding to Examples 1-3 of the present invention and the un-pre-lithiated negative electrode. Figure 3 The following are rate performance diagrams of solid-state batteries prepared by the present invention using silicon-based anode and un-lithiated silicon-carbon anode combined with Ni85 cathode, as prepared in Example 1 and Comparative Example 1, wherein the cycle rates are increased by 0.2C, 0.5C, 1C, 1.5C, 2C, and 3C and then decreased, respectively, and the cathode loading is 7 mg cm-2; (a) Example 1; (b) Comparative Example 1; Figure 4 The images show cross-sectional scanning electron microscope (SEM) images of the silicon-based anodes prepared in Example 1 and Comparative Example 1 of the present invention after 200 cycles at 0.5C. (a) Example 1; (b) Comparative Example 1. Detailed Implementation

[0022] The following detailed description, in conjunction with embodiments of the present invention and accompanying drawings, provides a clear and complete illustration of the technical solutions in these embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that all technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0024] Compared to existing technologies, the high volume expansion and structural cracking of traditional silicon-based anodes cause the active material to peel off from the current collector surface, leading to intensified polarization and capacity decay. The pretreated copper current collector prepared in this invention provides reliable current collector support for silicon-based lithium-ion batteries, significantly improving the long-cycle stability of silicon-based lithium-ion batteries.

[0025] The silicon, silicon-carbon, and silicon-oxygen materials used in this invention were all purchased from Shenzhen Huaxin New Materials Technology Co., Ltd., the 3-aminopropyltriethoxysilane was purchased from Beijing Innocare Technology Co., Ltd., and the 3-6µm ultrathin copper foil was purchased from Hubei Nord Lithium Battery Materials Co., Ltd.

[0026] This invention pre-treats copper current collectors and applies them to silicon-based anode batteries.

[0027] The ultrathin copper current collector was ultrasonically washed with phosphoric acid, acetone, and ethanol for 5 minutes respectively to remove surface oxides and oils, and then acid-washed and activated. The activated copper is immersed in a silane hydrolysate, the copper foil is removed and drained, and then cured at 100-150℃ for 5-30 minutes to form a covalently bonded Si-O-Cu interface layer on the copper foil surface. This interface layer generates strong ionic / amide bonds with the negative electrode binder (such as polyacrylic acid) through amino functional groups, significantly enhancing the interfacial adhesion, and finally obtaining a pretreated ultrathin copper foil current collector.

[0028] The ultrathin copper current collector uses copper foil with a thickness of 3~6µm.

[0029] The acid pickling and activation process uses at least one of sulfuric acid, hydrochloric acid, or citric acid solutions with a concentration of 5-10 vol%, and the treatment time is 30-120 seconds.

[0030] The curing process is carried out in an inert atmosphere or vacuum environment.

[0031] The silane coupling agent is at least one of vinylsilane, aminosilane, epoxysilane, or mercaptosilane, preferably 3-aminopropyltriethoxysilane (APTES). The copper foil surface has a layer of organic functional groups covalently linked by silicon-oxygen bonds (Si-O-Cu), including amino (-NH2), epoxy, or mercapto (-SH) groups. This interface layer forms strong ionic / amide bonds with the negative electrode binder (such as polyacrylic acid) through the organic functional groups, significantly enhancing the interfacial adhesion.

[0032] The second objective of this invention is to provide a silicon-based negative electrode sheet prepared by the above-mentioned preparation method, comprising the previously modified copper current collector and a negative electrode active layer coated on its surface; the negative electrode active layer comprises silicon-based material, conductive carbon and binder.

[0033] The silicon-based material accounts for ≥70% of the mass of the active layer, and the binder includes polyacrylic acid (PAA), sodium alginate, carboxymethyl cellulose, styrene-butadiene rubber, or polyimide.

[0034] Silicon-based materials are at least one of silicon-carbon materials, silicon-oxygen materials, and silicon materials.

[0035] The third objective of this invention is to provide a high-energy-density silicon-based negative electrode lithium battery, which is assembled from the aforementioned ultrathin copper current collector, silicon-based negative electrode material, positive electrode and liquid electrolyte.

[0036] Example 1: A pretreatment method for an ultrathin copper current collector includes the following steps: S1. Cut 3µm copper foil into 10×10 cm² sheets. Ultrasonically wash with phosphoric acid, acetone, and ethanol for 5 min, then immerse in 10 vol% sulfuric acid solution and ultrasonically treat for 45 s. Remove and rinse with deionized water until neutral, then dry in a nitrogen atmosphere. Extract 94 ml of anhydrous ethanol, 5 ml of deionized water, 0.1 ml of acetic acid, and 1 ml of 3-aminopropyltriethoxysilane. Dissolve anhydrous ethanol and glacial acetic acid in deionized water, adjust the pH to 4.5, and mix thoroughly with magnetic stirring. Add 3-aminopropyltriethoxysilane dropwise and continue stirring for 40 minutes.

[0037] S2. Immerse the copper foil dried in step S1 into the prepared solution for 2 minutes, and pull it up at a uniform speed to attach silane to the surface of the copper foil. After draining, place it in a vacuum oven and cure it at 120°C for 10 minutes under nitrogen atmosphere to form a silane interface layer, thus obtaining the pretreated ultrathin copper current collector.

[0038] The preparation method of silicon-based lithium-ion anode batteries includes the following steps: S3. Weigh 0.88g of silicon carbide material, 0.02g of graphene, 0.05g of polyacrylic acid (PAA) and 1g of deionized water. Mix the silicon material, graphene, polyacrylic acid solution and deionized water evenly to obtain silicon slurry.

[0039] S4. The silicon-carbon slurry from step S3 is coated onto the surface of the copper current collector, and the surface loading of the silicon-carbon material is controlled to be 3 mg / cm2. The material is then placed in a vacuum oven at 80°C for 12 hours to dry, thus obtaining a dried silicon anode sheet.

[0040] By matching the pretreated silicon-carbon anode with a 1.4 mAh / cm² Ni 85 cathode and using LiPF6 carbonate electrolyte, a high-energy-density lithium battery with a pretreated silicon-based anode was obtained.

[0041] Example 2: A pretreatment method for an ultrathin copper current collector includes the following steps: S1. Cut 5µm copper foil into 10×10 cm² sheets. Ultrasonically wash with phosphoric acid, acetone, and ethanol for 5 min, then immerse in 8 vol% hydrochloric acid solution for 90 s. Remove and rinse with deionized water until neutral, then dry in a nitrogen atmosphere. Extract 94 ml of anhydrous ethanol, 5 ml of deionized water, 0.1 ml of acetic acid, and 1 ml of vinyltriethoxysilane. Dissolve anhydrous ethanol and glacial acetic acid in deionized water, adjust the pH to 4.5, and mix thoroughly with magnetic stirring. Add vinyltriethoxysilane dropwise and continue stirring for 40 minutes.

[0042] S2. Immerse the dried copper foil from step S1 into the prepared solution for 2 minutes, and pull it up at a uniform speed to attach silane to the surface of the copper foil. After draining, place it in a vacuum oven and cure it at 120°C for 10 minutes under vacuum to form a silane interface layer, thus obtaining the pretreated ultrathin copper current collector.

[0043] The preparation method of silicon-based lithium-ion anode batteries includes the following steps: S3. Weigh 0.8g of silicon carbide material, 0.1g of carbon black, 0.1g of polyacrylic acid (PAA) and 1g of deionized water. Mix the silicon carbide material, carbon black, polyacrylic acid solution and deionized water evenly to obtain silicon slurry.

[0044] S4. The silicon-carbon slurry from step S3 is coated onto the surface of the copper current collector, and the surface loading of the silicon-carbon material is controlled to be 2 mg / cm2. The material is then placed in a vacuum oven at 80°C for 12 hours to dry, thus obtaining a dried silicon-carbon negative electrode sheet.

[0045] By matching the pretreated silicon-carbon anode with an NCM811 cathode with an areal capacity of 4 mAh / cm² and using LiPF6 carbonate electrolyte, a high-energy-density lithium battery with a pretreated silicon-carbon anode was obtained.

[0046] Comparative Example 1: A method for preparing a silicon-based lithium-ion anode battery includes the following steps: S1. Weigh 0.8g of silicon carbide material, 0.1g of carbon black, 0.1g of polyacrylic acid (PAA) and 1g of deionized water. Mix the silicon material, graphene, polyacrylic acid solution and deionized water evenly to obtain silicon carbide slurry.

[0047] S2. The silicon-carbon slurry from step S1 is coated onto the surface of a 3 µm copper metal current collector, and the silicon-carbon surface loading is controlled to be 3 mg / cm2. The mixture is then dried in a forced-air oven at 80°C for 2 hours and in a vacuum oven at 60°C for 12 hours to obtain a dried silicon anode sheet.

[0048] By matching a silicon-based anode with a 1.4 mAh / cm² Ni 85 cathode and using LiPF6 carbonate electrolyte, a high-energy-density lithium battery with a pretreated silicon-based anode was obtained.

[0049] Examples 1-2 of this invention all yielded pretreated silicon-based anode sheets and silicon-based lithium-ion batteries with excellent electrochemical performance. The pretreated silicon-based anode sheets from Examples 1-2 are compared with those from Comparative Example 1 (untreated silicon-based anode sheet and silicon-carbon lithium-ion battery). Specific research methods and results are shown below: Using the pretreated silicon-based negative electrode sheet from Example 1 and the untreated silicon-based negative electrode sheet from Comparative Example 1 as negative electrodes, and Ni 85 material with an areal capacity of 1.4 mAh / cm² as the positive electrode, their electrochemical stability was tested according to the following test methods, and the test results are as follows.Figure 1 As shown.

[0050] Test conditions: The battery was activated by charging and discharging at a rate of 0.1 C for the first three cycles, and then charged and discharged at a rate of 0.5 C for the cycle test. The Ni85 electrode used had a charge of 7 mg / cm2 and the charge and discharge voltage range was 3.0~4.3V.

[0051] And by Figure 1 The test results show that after 200 cycles, the battery assembled in Example 1 still has a specific capacity retention rate of 84.7%, which is a significant improvement compared to 25.8% in Comparative Example 1. This indicates that the pretreated silicon-based anode prepared by this process can significantly improve the cycle stability of silicon-based anode batteries.

[0052] Figure 2 This is a bar chart showing the electrochemical stability. (From...) Figure 2 It is evident that the addition of the pretreatment process significantly improves the electrochemical stability of the silicon-based anode material. This is attributed to the silane coupling agent hydrolysate, which, after being drained and cured, forms an interface layer on the copper foil surface, significantly enhancing the interfacial adhesion. Simultaneously, the flexible organic segments of the silane molecular layer can dynamically absorb the shear stress generated by silicon expansion, effectively suppressing the mechanical delamination between the active layer and the current collector.

[0053] Figure 3 In this study, the pretreated silicon-based negative electrode sheet of Example 1 and the untreated silicon-based negative electrode sheet of Comparative Example 1 were used as negative electrodes, and Ni 85 material with an areal capacity of 1.4 mAh / cm² was used as the positive electrode. Their cycle performance was tested according to the following test methods, and the test results are as follows: Figure 4 As shown.

[0054] Test conditions: Charge and discharge tests were conducted at current densities of 0.2C, 0.5C, 1C, 1.5C, 2C, 3.0C, and 0.2C, respectively, with the current density increasing first and then decreasing (1C=200mAh / g). The Ni 85 material used had a loading of 7mg / cm2, and the charge and discharge voltage range was 3.0V~4.3V.

[0055] Depend on Figure 3 The test results show that the lithium battery assembled with the silicon-based negative electrode sheet pretreated in Example 1 has good rate performance and greatly improves the specific capacity of the lithium battery under high rate charge and discharge.

[0056] Figure 4 In this study, taking the pretreated silicon-based negative electrode sheet prepared in Example 1 and the untreated silicon-based negative electrode sheet in Comparative Example 1 as examples, the microstructure of the cross-section of the negative electrode sheet after cycling was tested, and the test results are as follows. Figure 4 (a) and Figure 4 As shown in (b).

[0057] Depend on Figure 4 It can be seen that the silicon-carbon active material layer of the silicon-based anode sheet after pretreatment and the copper current collector still maintain a tight bond after 200 cycles at 0.5C, indicating that the silicon-based anode treated by the pretreatment process has been successfully prepared. Compared with Comparative Example 1, the silicon-based anode in contact with the pretreated ultrathin copper current collector is more flat and uniform, and the silicon-based material layer and the copper current collector have good interfacial compatibility.

[0058] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0059] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for pretreating an ultra-thin copper current collector, the method comprising: The method comprises the following steps: ​ ultrasonic washing the ultra-thin copper current collector with phosphoric acid, acetone and ethanol for 5 minutes to remove surface oxides and oils, and then performing acid washing activation; immersing the activated copper in a silane hydrolysis solution, taking out the copper foil and draining, and curing at a temperature of 100-150°C for 5-30 minutes to form a covalently bonded Si-O-Cu interface layer on the surface of the copper foil. The interface layer forms strong ionic amide bonds with the negative electrode binder through amino functional groups, significantly enhancing the interface bonding force, and finally obtaining a pretreated ultra-thin copper foil current collector.

2. The method of claim 1, wherein the copper is deposited to a thickness of 1- 10 microns. The ultra-thin copper current collector uses a copper foil with a thickness of 3-6µm.

3. The method of claim 1, wherein the copper is deposited to a thickness of 1- 10 microns. The acid washing activation uses at least one of a sulfuric acid solution, a hydrochloric acid solution or a citric acid solution with a concentration of 5-10 vol%, and the treatment time is 30S-120S.

4. The method of claim 1, wherein the copper is deposited to a thickness of 1- 10 microns. The curing process is carried out in an inert atmosphere or a vacuum environment.

5. The method of claim 1, wherein the copper is deposited to a thickness of 1- 10 microns. The silane coupling agent is at least one of a vinyl silane, an amino silane, an epoxy silane or a mercapto silane.

6. A modified copper current collector characterized by, The surface of the ultra-thin copper current collector prepared by the preparation method of any one of claims 1-5 has an organic functional group layer covalently connected by a silicon-oxygen bond (Si-O-Cu), and the functional groups include amino groups (-NH2), epoxy groups or mercapto groups (-SH).

7. A silicon-based negative lithium battery, characterized in that, The modified copper current collector of claim 6 is assembled with a silicon-based negative electrode sheet, a positive electrode and a liquid electrolyte.

8. The silicon-based anode lithium battery of claim 7, wherein, The silicon-based negative electrode sheet comprises a modified copper current collector and a negative active layer coated on the surface thereof; the negative active layer comprises a silicon-based material, conductive carbon and a binder.

9. The silicon-based anode lithium battery of claim 8, wherein, The mass fraction of the silicon-based material in the active layer is ≥70%, and the binder comprises polyacrylic acid (PAA), sodium alginate, carboxymethyl cellulose, butadiene rubber or polyimide.

10. The silicon-based negative electrode sheet according to claim 8, characterized by The silicon-based material is at least one of a silicon-carbon material, a silicon-oxygen material or a silicon material.

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