Preparation method of prime-coated copper foil for improving cycle performance of silica material

Abstract

The invention relates to the technical field of prime coat copper foils, in particular to a prime coat copper foil preparation method for improving the cycle performance of a silica material, which comprises the following steps: step 1, mixing pure water and polyacrylic acid, sequentially adding acetylene black, isopropanol, LLZO and LiNO3, and uniformly stirring to obtain prime coat slurry; step 2, coating a copper foil with the prime coat slurry, and drying to obtain a prime coat copper foil; lLZO and LiNO3 are introduced into the bottom coating, so that the volume deformation of the silica material can be effectively relieved, the puncture of lithium dendrites is inhibited, and the cycle performance and safety of the battery are improved.

Description

Technical Field

[0001] This invention relates to the field of bottom-coated copper foil technology, specifically to a method for preparing bottom-coated copper foil that improves the cycling performance of silicon-oxygen materials. Background Technology

[0002] With the rapid development of the new energy industry, lithium batteries are demanding higher energy densities. Traditional graphite anodes can no longer meet these requirements, and silicon-oxygen materials, due to their high theoretical specific capacity, are considered an ideal choice for next-generation anode materials, attracting significant attention from the industry. However, silicon-oxygen materials exhibit significant volume expansion and contraction during charge and discharge. This inherent volume effect leads to structural pulverization of the active material, internal electrode contact failure, and continuous electrolyte decomposition. During repeated lithium insertion / extraction, the solid electrolyte interphase (SEI) film on the surface of the silicon-oxygen material continuously ruptures and regenerates, not only continuously consuming limited electrolyte and active lithium ions, resulting in reduced coulombic efficiency and capacity decay, but also easily inducing lithium dendrite growth, posing safety hazards. These problems severely restrict the practical application of silicon-oxygen anodes and the improvement of their long-cycle stability.

[0003] To overcome the aforementioned shortcomings, recent research has focused on material nanostructuring, composite structure design, and interface control. Among these, constructing a functional undercoating on the current collector surface is considered an effective solution. By designing a multifunctional undercoating that buffers volume deformation, guides uniform lithium deposition, and promotes the formation of a stable SEI film, it is hoped that by addressing the current collector interface, volume expansion can be simultaneously mitigated, lithium dendrite formation suppressed, and active lithium loss reduced, thereby improving the overall electrochemical performance of silicon-oxygen anodes. This study aims to develop a method for preparing an undercoated copper foil to address key technical bottlenecks such as poor cycle stability and rapid capacity decay of silicon-oxygen materials. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a base-coated copper foil that improves the cycling performance of silicon-oxygen materials, thereby solving the problems raised in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: Step 1: Mix pure water and polyacrylic acid, then add acetylene black, isopropanol, LLZO and LiNO3 in sequence, and stir evenly to obtain the primer slurry; Step 2: Apply a primer slurry to the copper foil and dry it to obtain a primer-coated copper foil.

[0006] Furthermore, the solid content of the primer slurry is 10%; the mass of LLZO is 1.4% to 2.4% of the solid mass of the primer slurry, and the mass of LiNO3 is 2.5% to 5% of the solid mass of the primer slurry.

[0007] Furthermore, the thickness of the copper foil is 7~9μm.

[0008] Furthermore, the coating speed in step 2 is 55~65 m / min, and the single-layer coating density is 0.4~0.6 g / m³. 2 The drying temperature is 95~105℃.

[0009] Furthermore, applying the base-coated copper foil to a button cell includes the following steps: S1: Mix and stir the negative electrode active material BSO-2, binder LA132 and conductive agent Super P evenly, coat it on the base copper foil, and dry it to obtain the negative electrode sheet; S2: In a glove box under argon protection, the button cell is assembled in the following order: button cell casing, negative electrode, separator, positive electrode, gasket, and button cell casing. Electrolyte is added before and after placing the separator to obtain the button cell.

[0010] Furthermore, in S1, the negative electrode active material BSO-2, binder LA132, and conductive agent Super P are mixed in a mass ratio of 8:1:1; the drying temperature in S1 is 65~75℃, and the drying time is 0.5~1.5h.

[0011] Furthermore, the polyacrylic acid described in step 1 undergoes modification treatment, including the following steps: Polyacrylic acid was dissolved in anhydrous ethanol, and 2,2-dihydroxymethylbutyric acid was also dissolved in anhydrous ethanol. The solutions were stirred separately until dissolved. The two solutions were mixed at 20-25°C and stirred continuously for 2-4 hours. The mixture was then dried at 40-50°C for 23-25 ​​hours to obtain modified polyacrylic acid.

[0012] Furthermore, the polyacrylic acid and anhydrous ethanol are mixed at a mass ratio of 1:500; 2,2-dimethylolbutyric acid and anhydrous ethanol are mixed at a mass ratio of 1:200; and the mass ratio of polyacrylic acid to 2,2-dimethylolbutyric acid is 2:1.

[0013] Furthermore, the acetylene black described in step 1 undergoes a modification treatment, including the following steps: Acetylene black was vacuum dried at 55-65℃ for 23-25 ​​hours, and then its surface was acidified and modified with concentrated nitric acid vapor in a closed system to obtain acid-modified acetylene black. Sublimed sulfur that had been sieved was mixed with acid-modified acetylene black and ball-milled at 250-350 r / min for 9-11 hours to obtain a mixture. The mixture was then heat-treated at 150-160℃ for 11-13 hours under a nitrogen atmosphere to obtain modified acetylene black.

[0014] Furthermore, the sublimed sulfur and acid-modified acetylene black are mixed at a mass ratio of 14:6.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention describes a method for preparing a base-coated copper foil to improve the cycle performance of silicon-oxygen materials. The base coating not only contains a binder and a conductive agent, but also contains two functional components: lithium lanthanum zirconium oxide (LLZO) and LiNO3. The high-modulus LLZO particles effectively buffer the volume expansion of the silicon-oxygen material, suppress lithium dendrite puncture, and improve battery safety. Simultaneously, its excellent lithium-ion conductivity promotes uniform distribution of lithium ions on the current collector surface, avoiding local concentration polarization and thus extending cycle life. LiNO3 can be reduced to Li3N and Li2O at low potentials, forming a dense and stable artificial SEI film, reducing repeated damage and regeneration of the SEI film during charge and discharge, and lowering active lithium loss. Furthermore, its own lithium source can compensate for irreversible capacity loss during the first cycle, contributing to improved battery energy density.

[0016] 2. The method for preparing a copper foil base coating to improve the cycling performance of silicon-oxygen materials described in this invention addresses the issue that the carboxyl groups in polyacrylic acid (PAA) molecules easily form intramolecular hydrogen bonds, leading to chain entanglement. This is achieved by introducing 2,2-dihydroxymethylbutyric acid (2,2-dihydroxymethylbutyric acid), whose active hydroxymethyl groups are grafted onto the carboxyl groups of PAA through esterification. This not only inhibits chain entanglement but also introduces abundant hydroxyl groups into the PAA backbone, forming a dynamic hydrogen bond cross-linking network that significantly enhances the flexibility and interfacial adhesion of the binder. Acetylene black, after being oxidized with concentrated nitric acid to introduce oxygen-containing functional groups, is then thermally polymerized with sublimed sulfur to form an SC composite structure. This sulfur composite structure optimizes the conductive network, significantly improving electronic conductivity and stability. In the base coating, LLZO provides lithium-ion channels, while LiNO3 electrochemically decomposes to form a stable SEI film of Li3N, promoting interfacial bonding and lithium-ion transport. The ion-electron dual conductive layer synergistically stabilizes the interfacial dynamics, thereby systematically inhibiting the expansion of silicon-oxygen materials, reducing side reactions, and significantly improving cycling performance.

[0017] 3. A method for preparing a copper foil with a bottom coating for improving the cycling performance of silicon-oxygen materials described in the present invention uses the rich hydroxyl groups of modified polyacrylic acid and the carboxyl groups on the surface of modified acetylene black to form a covalent cross-linked network through esterification condensation, achieving strong interfacial chemical bonding between the conductive agent and the polymer. This not only significantly enhances the mechanical robustness of the electrode structure, effectively adapts to and suppresses the volume deformation of silicon-oxygen materials during the lithium intercalation / delithiation process, but also ensures the lasting integrity of the electron transport path by constructing a conductive network with stable topological connections, thereby suppressing the electrochemical polarization caused by contact failure. This conductive network also provides uniform dispersion sites for LLZO, optimizes the lithium ion transport path through coordination, and collaboratively constructs a stable gradient SEI film with the decomposition products of LiNO3. The C-S bonded sulfur in acetylene black controllably releases active lithium during charge and discharge, in-situ compensating for the consumption during SEI formation, and its reaction product Li2S further consolidates the ionic conductivity of the interface layer. The capacity decay problem of silicon-oxygen materials is improved from three aspects: mechanical support, interface stability, and active lithium compensation. Detailed implementation manners

[0018] Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0019] In the following detailed implementation manners, the sources of raw materials Polyacrylic acid: Product number XW01900301402, sourced from Sinopharm Chemical Reagent Co., Ltd. Acetylene black: Product number MY38641, sourced from Shanghai Xianding Biotechnology Co., Ltd. Anode active material: Model BSO-2, sourced from BETRAY New Materials Group Co., Ltd. Binder: Model LA132, sourced from Zhengzhou Alpha Chemical Co., Ltd. Super P: Model ENSACO, sourced from IMERYS. Button battery case: Model CR2032, sourced from Guangdong Zhuguang New Energy Technology Co., Ltd. Electrolyte: Model MA-EN-ET-035101, sourced from Guangdong Zhuguang New Energy Technology Co., Ltd. Separator: Thickness 20μm, product number 072, sourced from Guangdong Blue Green Film Technology Co., Ltd. Positive electrode sheet: Model CU-EL-PL-1002, sourced from Guangdong Zhuguang New Energy Technology Co., Ltd. Gasket spring piece: Specification 16.1×0.5mm, sourced from Guangdong Zhuguang New Energy Technology Co., Ltd. 2,2-Dihydroxymethylbutyric acid: Product number S30543, sourced from Shanghai Yuanye Biotechnology Co., Ltd.; Sublimed sulfur: Product number 80120528, sourced from Sinopharm Chemical Reagent Co., Ltd.; Isopropanol, lithium lanthanum zirconium oxide (LLZO), LiNO3, and concentrated nitric acid were all of analytical grade.

[0020] Example 1: A method for preparing a base-coated copper foil to improve the cycling performance of silicon-oxygen materials, comprising the following steps: Step 1: Mix pure water and polyacrylic acid, then add acetylene black, isopropanol, LLZO and LiNO3 in sequence, and stir until homogeneous to obtain a primer slurry with a solid content of 10%; wherein the mass ratio of polyacrylic acid to acetylene black is 2:3, the mass of LLZO is 1.8% of the solid mass of the primer slurry, the mass of LiNO3 is 3.5% of the solid mass of the primer slurry, the mass of isopropanol is 10% of the total mass of the primer slurry, and the remainder is pure water; Step 2: Apply a primer slurry to an 8μm copper foil at a coating speed of 60m / min, dry at 100℃, and achieve a single-layer coating density of 0.5g / m². 2 This yields a base-coated copper foil; The copper foil base coating is applied to button batteries, including the following steps: S1: Mix the negative electrode active material BSO-2, binder LA132 and conductive agent Super P in a mass ratio of 8:1:1 and stir evenly. Coat the mixture onto the base copper foil and dry it in a vacuum drying oven at 70℃ for 1 hour to obtain the negative electrode sheet. S2: In a glove box under argon protection, the button cell is assembled in the following order: button cell casing, negative electrode, separator, positive electrode, gasket, and button cell casing. Electrolyte is added before and after placing the separator to obtain the button cell.

[0021] Example 2: A method for preparing a base-coated copper foil to improve the cycling performance of silicon-oxygen materials, comprising the following steps: Step 1: Mix pure water and polyacrylic acid, then add acetylene black, isopropanol, LLZO and LiNO3 in sequence, and stir until homogeneous to obtain a primer slurry with a solid content of 10%; wherein the mass ratio of polyacrylic acid to acetylene black is 2:3, the mass of LLZO is 1.4% of the solid mass of the primer slurry, the mass of LiNO3 is 3.5% of the solid mass of the primer slurry, the mass of isopropanol is 10% of the total mass of the primer slurry, and the remainder is pure water; Step 2: Apply a primer slurry to an 8μm copper foil at a coating speed of 60m / min, dry at 100℃, and achieve a single-layer coating density of 0.5g / m². 2 This yields a base-coated copper foil; The copper foil base coating is applied to button batteries, including the following steps: S1: Mix the negative electrode active material BSO-2, binder LA132 and conductive agent Super P in a mass ratio of 8:1:1 and stir evenly. Coat the mixture onto the base copper foil and dry it in a vacuum drying oven at 70℃ for 1 hour to obtain the negative electrode sheet. S2: In a glove box under argon protection, the button cell is assembled in the following order: button cell casing, negative electrode, separator, positive electrode, gasket, and button cell casing. Electrolyte is added before and after placing the separator to obtain the button cell.

[0022] Example 3: A method for preparing a base-coated copper foil to improve the cycling performance of silicon-oxygen materials, comprising the following steps: Step 1: Mix pure water and polyacrylic acid, then add acetylene black, isopropanol, LLZO and LiNO3 in sequence, and stir until homogeneous to obtain a primer slurry with a solid content of 10%; wherein the mass ratio of polyacrylic acid to acetylene black is 2:3, the mass of LLZO is 1.6% of the solid mass of the primer slurry, the mass of LiNO3 is 3.5% of the solid mass of the primer slurry, the mass of isopropanol is 10% of the total mass of the primer slurry, and the remainder is pure water; Step 2: Apply a primer slurry to an 8μm copper foil at a coating speed of 60m / min, dry at 100℃, and achieve a single-layer coating density of 0.5g / m². 2 This yields a base-coated copper foil; The copper foil base coating is applied to button batteries, including the following steps: S1: Mix the negative electrode active material BSO-2, binder LA132 and conductive agent Super P in a mass ratio of 8:1:1 and stir evenly. Coat the mixture onto the base copper foil and dry it in a vacuum drying oven at 70℃ for 1 hour to obtain the negative electrode sheet. S2: In a glove box under argon protection, the button cell is assembled in the following order: button cell casing, negative electrode, separator, positive electrode, gasket, and button cell casing. Electrolyte is added before and after placing the separator to obtain the button cell.

[0023] Example 4: A method for preparing a base-coated copper foil to improve the cycling performance of silicon-oxygen materials, comprising the following steps: Step 1: Mix pure water and polyacrylic acid, then add acetylene black, isopropanol, LLZO and LiNO3 in sequence, and stir until homogeneous to obtain a primer slurry with a solid content of 10%; wherein the mass ratio of polyacrylic acid to acetylene black is 2:3, the mass of LLZO is 2% of the solid mass of the primer slurry, the mass of LiNO3 is 3.5% of the solid mass of the primer slurry, the mass of isopropanol is 10% of the total mass of the primer slurry, and the remainder is pure water; Step 2: Apply a primer slurry to an 8μm copper foil at a coating speed of 60m / min, dry at 100℃, and achieve a single-layer coating density of 0.5g / m². 2 This yields a base-coated copper foil; The copper foil base coating is applied to button batteries, including the following steps: S1: Mix the negative electrode active material BSO-2, binder LA132 and conductive agent Super P in a mass ratio of 8:1:1 and stir evenly. Coat the mixture onto the base copper foil and dry it in a vacuum drying oven at 70℃ for 1 hour to obtain the negative electrode sheet. S2: In a glove box under argon protection, the button cell is assembled in the following order: button cell casing, negative electrode, separator, positive electrode, gasket, and button cell casing. Electrolyte is added before and after placing the separator to obtain the button cell.

[0024] Example 5: A method for preparing a base-coated copper foil to improve the cycling performance of silicon-oxygen materials, comprising the following steps: Step 1: Mix pure water and polyacrylic acid, then add acetylene black, isopropanol, LLZO and LiNO3 in sequence, and stir until homogeneous to obtain a primer slurry with a solid content of 10%; wherein the mass ratio of polyacrylic acid to acetylene black is 2:3, the mass of LLZO is 2.2% of the solid mass of the primer slurry, the mass of LiNO3 is 3.5% of the solid mass of the primer slurry, the mass of isopropanol is 10% of the total mass of the primer slurry, and the remainder is pure water; Step 2: Apply a primer slurry to an 8μm copper foil at a coating speed of 60m / min, dry at 100℃, and achieve a single-layer coating density of 0.5g / m². 2 This yields a base-coated copper foil; The copper foil base coating is applied to button batteries, including the following steps: S1: Mix the negative electrode active material BSO-2, binder LA132 and conductive agent Super P in a mass ratio of 8:1:1 and stir evenly. Coat the mixture onto the base copper foil and dry it in a vacuum drying oven at 70℃ for 1 hour to obtain the negative electrode sheet. S2: In a glove box under argon protection, the button cell is assembled in the following order: button cell casing, negative electrode, separator, positive electrode, gasket, and button cell casing. Electrolyte is added before and after placing the separator to obtain the button cell.

[0025] Example 6: A method for preparing a base-coated copper foil to improve the cycling performance of silicon-oxygen materials, comprising the following steps: Step 1: Mix pure water and polyacrylic acid, then add acetylene black, isopropanol, LLZO and LiNO3 in sequence, and stir until homogeneous to obtain a primer with a solid content of 10%; wherein the mass ratio of polyacrylic acid to acetylene black is 2:3, the mass of LLZO is 1.8% of the solid mass of the primer, the mass of LiNO3 is 2.5% of the solid mass of the primer, the mass of isopropanol is 10% of the total mass of the primer, and the remainder is pure water; Step 2: Apply a primer slurry to an 8μm copper foil at a coating speed of 60m / min, dry at 100℃, and achieve a single-layer coating density of 0.5g / m². 2 This yields a base-coated copper foil; The copper foil base coating is applied to button batteries, including the following steps: S1: Mix the negative electrode active material BSO-2, binder LA132 and conductive agent Super P in a mass ratio of 8:1:1 and stir evenly. Coat the mixture onto the base copper foil and dry it in a vacuum drying oven at 70℃ for 1 hour to obtain the negative electrode sheet. S2: In a glove box under argon protection, the button cell is assembled in the following order: button cell casing, negative electrode, separator, positive electrode, gasket, and button cell casing. Electrolyte is added before and after placing the separator to obtain the button cell.

[0026] Example 7: A method for preparing a base-coated copper foil to improve the cycling performance of silicon-oxygen materials, comprising the following steps: Step 1: Mix pure water and polyacrylic acid, then add acetylene black, isopropanol, LLZO and LiNO3 in sequence, and stir until homogeneous to obtain a primer slurry with a solid content of 10%; wherein the mass ratio of polyacrylic acid to acetylene black is 2:3, the mass of LLZO is 1.8% of the solid mass of the primer slurry, the mass of LiNO3 is 3% of the solid mass of the primer slurry, the mass of isopropanol is 10% of the total mass of the primer slurry, and the remainder is pure water; Step 2: Apply a primer slurry to an 8μm copper foil at a coating speed of 60m / min, dry at 100℃, and achieve a single-layer coating density of 0.5g / m². 2 This yields a base-coated copper foil; The copper foil base coating is applied to button batteries, including the following steps: S1: Mix the negative electrode active material BSO-2, binder LA132 and conductive agent Super P in a mass ratio of 8:1:1 and stir evenly. Coat the mixture onto the base copper foil and dry it in a vacuum drying oven at 70℃ for 1 hour to obtain the negative electrode sheet. S2: In a glove box under argon protection, the button cell is assembled in the following order: button cell casing, negative electrode, separator, positive electrode, gasket, and button cell casing. Electrolyte is added before and after placing the separator to obtain the button cell.

[0027] Example 8: A method for preparing a base-coated copper foil to improve the cycling performance of silicon-oxygen materials, comprising the following steps: Step 1: Mix pure water and polyacrylic acid, then add acetylene black, isopropanol, LLZO and LiNO3 in sequence, and stir until homogeneous to obtain a primer slurry with a solid content of 10%; wherein the mass ratio of polyacrylic acid to acetylene black is 2:3, the mass of LLZO is 1.8% of the solid mass of the primer slurry, the mass of LiNO3 is 4% of the solid mass of the primer slurry, the mass of isopropanol is 10% of the total mass of the primer slurry, and the remainder is pure water; Step 2: Apply a primer slurry to an 8μm copper foil at a coating speed of 60m / min, dry at 100℃, and achieve a single-layer coating density of 0.5g / m². 2 This yields a base-coated copper foil; The copper foil base coating is applied to button batteries, including the following steps: S1: Mix the negative electrode active material BSO-2, binder LA132 and conductive agent Super P in a mass ratio of 8:1:1 and stir evenly. Coat the mixture onto the base copper foil and dry it in a vacuum drying oven at 70℃ for 1 hour to obtain the negative electrode sheet. S2: In a glove box under argon protection, the button cell is assembled in the following order: button cell casing, negative electrode, separator, positive electrode, gasket, and button cell casing. Electrolyte is added before and after placing the separator to obtain the button cell.

[0028] Example 9: A method for preparing a base-coated copper foil to improve the cycling performance of silicon-oxygen materials, comprising the following steps: Step 1: Mix pure water and polyacrylic acid, then add acetylene black, isopropanol, LLZO and LiNO3 in sequence, and stir until homogeneous to obtain a primer slurry with a solid content of 10%; wherein the mass ratio of polyacrylic acid to acetylene black is 2:3, the mass of LLZO is 1.8% of the solid mass of the primer slurry, the mass of LiNO3 is 4.5% of the solid mass of the primer slurry, the mass of isopropanol is 10% of the total mass of the primer slurry, and the remainder is pure water; Step 2: Apply a primer slurry to an 8μm copper foil at a coating speed of 60m / min, dry at 100℃, and achieve a single-layer coating density of 0.5g / m². 2 This yields a base-coated copper foil; The copper foil base coating is applied to button batteries, including the following steps: S1: Mix the negative electrode active material BSO-2, binder LA132 and conductive agent Super P in a mass ratio of 8:1:1 and stir evenly. Coat the mixture onto the base copper foil and dry it in a vacuum drying oven at 70℃ for 1 hour to obtain the negative electrode sheet. S2: In a glove box under argon protection, the button cell is assembled in the following order: button cell casing, negative electrode, separator, positive electrode, gasket, and button cell casing. Electrolyte is added before and after placing the separator to obtain the button cell.

[0029] Example 10: Polyacrylic acid and acetylene black were modified using Example 1 as a control, with the remaining steps and process parameters being the same as in Example 1; Step 1: Mix pure water and polyacrylic acid, then add acetylene black, isopropanol, LLZO and LiNO3 in sequence, and stir until homogeneous to obtain a primer slurry with a solid content of 10%; wherein the mass ratio of polyacrylic acid to acetylene black is 2:3, the mass of LLZO is 1.8% of the solid mass of the primer slurry, the mass of LiNO3 is 3.5% of the solid mass of the primer slurry, the mass of isopropanol is 10% of the total mass of the primer slurry, and the remainder is pure water; Step 2: Apply a primer slurry to an 8μm copper foil at a coating speed of 60m / min, dry at 100℃, and achieve a single-layer coating density of 0.5g / m². 2 This yields a base-coated copper foil; The copper foil base coating is applied to button batteries, including the following steps: S1: Mix the negative electrode active material BSO-2, binder LA132 and conductive agent Super P in a mass ratio of 8:1:1 and stir evenly. Coat the mixture onto the base copper foil and dry it in a vacuum drying oven at 70℃ for 1 hour to obtain the negative electrode sheet. S2: In a glove box under argon protection, the button cell is assembled in the following order: button cell casing, negative electrode, separator, positive electrode, gasket spring and button cell casing. Electrolyte is added before and after placing the separator to obtain the button cell. The polyacrylic acid has undergone modification treatment, including the following steps: 1 g of polyacrylic acid was dissolved in 500 mL of anhydrous ethanol, and 0.5 g of 2,2-dihydroxymethylbutyric acid was dissolved in 100 mL of anhydrous ethanol. The two solutions were stirred until completely dissolved. The two solutions were mixed at 20 °C and stirred continuously for 2 h to ensure that the reaction was complete. The mixture was dried at 40 °C for 23 h to obtain modified polyacrylic acid. The acetylene black undergoes modification treatment, including the following steps: 10g of acetylene black was vacuum dried at 55℃ for 23h, and then its surface was acidified and modified with concentrated nitric acid vapor in a closed system to obtain acid-modified acetylene black. 14g of sublimed sulfur that had passed through a 400-mesh sieve was mixed with 6g of acid-modified acetylene black and ball-milled at 250r / min for 9h using a planetary ball mill to obtain a mixture. The mixture was placed in a tube furnace under a nitrogen atmosphere and heat-treated at 150℃ for 11h to obtain modified acetylene black.

[0030] Example 11: Using Example 1 as a control, polyacrylic acid and acetylene black were modified, with the remaining steps and process parameters being the same as in Example 1; Step 1: Mix pure water and polyacrylic acid, then add acetylene black, isopropanol, LLZO and LiNO3 in sequence, and stir until homogeneous to obtain a primer slurry with a solid content of 10%; wherein the mass ratio of polyacrylic acid to acetylene black is 2:3, the mass of LLZO is 1.8% of the solid mass of the primer slurry, the mass of LiNO3 is 3.5% of the solid mass of the primer slurry, the mass of isopropanol is 10% of the total mass of the primer slurry, and the remainder is pure water; Step 2: Apply a primer slurry to an 8μm copper foil at a coating speed of 60m / min, dry at 100℃, and achieve a single-layer coating density of 0.5g / m². 2 This yields a base-coated copper foil; The copper foil base coating is applied to button batteries, including the following steps: S1: Mix the negative electrode active material BSO-2, binder LA132 and conductive agent Super P in a mass ratio of 8:1:1 and stir evenly. Coat the mixture onto the base copper foil and dry it in a vacuum drying oven at 70℃ for 1 hour to obtain the negative electrode sheet. S2: In a glove box under argon protection, the button cell is assembled in the following order: button cell casing, negative electrode, separator, positive electrode, gasket spring and button cell casing. Electrolyte is added before and after placing the separator to obtain the button cell. The polyacrylic acid has undergone modification treatment, including the following steps: 2g of polyacrylic acid was dissolved in 1000mL of anhydrous ethanol, and 1g of 2,2-dihydroxymethylbutyric acid was dissolved in 200mL of anhydrous ethanol. The solutions were stirred until completely dissolved. The two solutions were mixed at 23°C and stirred continuously for 3 hours to ensure that the reaction was complete. The mixture was then dried at 45°C for 24 hours to obtain modified polyacrylic acid. The acetylene black undergoes modification treatment, including the following steps: 20g of acetylene black was vacuum dried at 60℃ for 24h, and then its surface was acidified and modified with concentrated nitric acid vapor in a closed system to obtain acid-modified acetylene black. 28g of sublimed sulfur that passed through a 400-mesh sieve was mixed with 12g of acid-modified acetylene black and ball-milled at 300r / min for 10h using a planetary ball mill to obtain a mixture. The mixture was placed in a tube furnace under a nitrogen atmosphere and heat-treated at 155℃ for 12h to obtain modified acetylene black.

[0031] Example 12: Using Example 1 as a control, polyacrylic acid and acetylene black were modified, with the remaining steps and process parameters being the same as in Example 1; Step 1: Mix pure water and polyacrylic acid, then add acetylene black, isopropanol, LLZO and LiNO3 in sequence, and stir until homogeneous to obtain a primer slurry with a solid content of 10%; wherein the mass ratio of polyacrylic acid to acetylene black is 2:3, the mass of LLZO is 1.8% of the solid mass of the primer slurry, the mass of LiNO3 is 3.5% of the solid mass of the primer slurry, the mass of isopropanol is 10% of the total mass of the primer slurry, and the remainder is pure water; Step 2: Apply a primer slurry to an 8μm copper foil at a coating speed of 60m / min, dry at 100℃, and achieve a single-layer coating density of 0.5g / m². 2 This yields a base-coated copper foil; The copper foil base coating is applied to button batteries, including the following steps: S1: Mix the negative electrode active material BSO-2, binder LA132 and conductive agent Super P in a mass ratio of 8:1:1 and stir evenly. Coat the mixture onto the base copper foil and dry it in a vacuum drying oven at 70℃ for 1 hour to obtain the negative electrode sheet. S2: In a glove box under argon protection, the button cell is assembled in the following order: button cell casing, negative electrode, separator, positive electrode, gasket spring and button cell casing. Electrolyte is added before and after placing the separator to obtain the button cell. The polyacrylic acid has undergone modification treatment, including the following steps: 3g of polyacrylic acid was dissolved in 1500mL of anhydrous ethanol, and 1.5g of 2,2-dihydroxymethylbutyric acid was dissolved in 300mL of anhydrous ethanol. The solutions were stirred until completely dissolved. The two solutions were mixed at 25°C and stirred continuously for 4 hours to ensure that the reaction was complete. The mixture was then dried at 50°C for 25 hours to obtain modified polyacrylic acid. The acetylene black undergoes modification treatment, including the following steps: 30g of acetylene black was vacuum dried at 65℃ for 25h, and then its surface was acidified and modified with concentrated nitric acid vapor in a closed system to obtain acid-modified acetylene black. 42g of sublimed sulfur that passed through a 400-mesh sieve was mixed with 18g of acid-modified acetylene black and ball-milled at 350r / min for 11h using a planetary ball mill to obtain a mixture. The mixture was placed in a tube furnace under a nitrogen atmosphere and heat-treated at 160℃ for 13h to obtain modified acetylene black.

[0032] Comparative Example 1: Compared with Example 1, LLZO was not added, and the remaining steps were the same as in Example 1.

[0033] Comparative Example 2: Compared with Example 1, LiNO3 was not added, and the remaining steps were the same as in Example 1.

[0034] Comparative Example 3: Compared with Example 1, no primer was applied to the copper foil, and the remaining steps were the same as in Example 1.

[0035] Comparative Example 4: Compared with Example 12, the polyacrylic acid used was unmodified, and the remaining steps were the same as in Example 12.

[0036] Comparative Example 5: Compared with Example 12, the acetylene black used was not modified, and the remaining steps were the same as in Example 12.

[0037] Experiment: The button batteries prepared in Examples 1-12 and Comparative Examples 1-5 were used to conduct 10, 30 and 50 charge-discharge tests on them using a button battery charge-discharge tester. The charge-discharge current was 0.2C and the charge-discharge voltage was 0.01~1.5V. The test results are shown in Table 1.

[0038] Table 1

[0039] As shown in Table 1, the batteries in Examples 1-9 (basic formulation) all exhibited a capacity retention rate better than 82% after 50 cycles, significantly higher than Comparative Example 3 (no base coating), Comparative Example 1 (lacking the key component LLZO), and Comparative Example 2 (lacking the key component LiNO3). This verifies the core advantage of introducing LLZO and LiNO3 into the base coating, which effectively buffers volume deformation and forms a stable SEI film, thereby improving cycle life. Examples 10-12 achieved a significant performance improvement using a preferred scheme of modified polyacrylic acid and modified acetylene black. Among them, the optimal Example 12 showed a capacity retention rate far exceeding that of the basic formulation and the control groups (Comparative Example 4 and Comparative Example 5) after 50 cycles. The results strongly confirm the chemical synergistic advantages brought about by the modification process: the covalent cross-linked network formed between the modified polyacrylic acid and the modified acetylene black achieves strong interfacial bonding between the conductive agent and the binder, constructs a stable structure, thereby enhancing the mechanical robustness of the electrode against the volume change of silicon-oxygen materials, and ensuring the long-term integrity of the electron transport pathway, ultimately systematically improving the long-cycle stability of the battery.

[0040] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a base-coated copper foil to improve the cycling performance of silicon-oxygen materials, characterized in that: Includes the following steps: Step 1: Mix pure water and polyacrylic acid, then add acetylene black, isopropanol, LLZO and LiNO3 in sequence, and stir evenly to obtain the primer slurry; Step 2: Apply a primer slurry to the copper foil and dry it to obtain a primer-coated copper foil.

2. The method for preparing a base-coated copper foil to improve the cycle performance of silicon-oxygen materials according to claim 1, characterized in that: The solid content of the primer slurry is 10%; the mass of LLZO is 1.4% to 2.4% of the solid mass of the primer slurry, and the mass of LiNO3 is 2.5% to 5% of the solid mass of the primer slurry.

3. The method for preparing a base-coated copper foil to improve the cycling performance of silicon-oxygen materials according to claim 1, characterized in that: The thickness of the copper foil is 7~9μm.

4. The method for preparing a base-coated copper foil to improve the cycle performance of silicon-oxygen materials according to claim 1, characterized in that: The coating speed in step 2 is 55~65 m / min, and the single-layer coating density is 0.4~0.6 g / m³. 2 The drying temperature is 95~105℃.

5. The method for preparing a base-coated copper foil to improve the cycle performance of silicon-oxygen materials according to claim 1, characterized in that: Applying the copper foil base coating to a button cell includes the following steps: S1: Mix and stir the negative electrode active material BSO-2, binder LA132 and conductive agent Super P evenly, coat it on the base copper foil, and dry it to obtain the negative electrode sheet; S2: In a glove box under argon protection, the button cell is assembled in the following order: button cell casing, negative electrode, separator, positive electrode, gasket, and button cell casing. Electrolyte is added before and after placing the separator to obtain the button cell.

6. The method for preparing a base-coated copper foil to improve the cycling performance of silicon-oxygen materials according to claim 5, characterized in that: The negative electrode active material BSO-2, binder LA132 and conductive agent Super P in S1 are mixed in a mass ratio of 8:1:1; the drying temperature in S1 is 65~75℃ and the drying time is 0.5~1.5h.

7. The method for preparing a base-coated copper foil to improve the cycle performance of silicon-oxygen materials according to claim 1, characterized in that: The polyacrylic acid described in step 1 undergoes modification treatment, including the following steps: Polyacrylic acid was dissolved in anhydrous ethanol, and 2,2-dihydroxymethylbutyric acid was also dissolved in anhydrous ethanol. The solutions were stirred separately until dissolved. The two solutions were mixed at 20-25°C and stirred continuously for 2-4 hours. The mixture was then dried at 40-50°C for 23-25 ​​hours to obtain modified polyacrylic acid.

8. The method for preparing a base-coated copper foil to improve the cycle performance of silicon-oxygen materials according to claim 7, characterized in that: The polyacrylic acid and anhydrous ethanol are mixed at a mass ratio of 1:500; 2,2-dimethylolbutyric acid and anhydrous ethanol are mixed at a mass ratio of 1:200; and the mass ratio of polyacrylic acid to 2,2-dimethylolbutyric acid is 2:

1.

9. The method for preparing a base-coated copper foil to improve the cycle performance of silicon-oxygen materials according to claim 1, characterized in that: The acetylene black described in step 1 undergoes a modification treatment, including the following steps: Acetylene black was vacuum dried at 55-65℃ for 23-25 ​​hours, and then its surface was acidified and modified with concentrated nitric acid vapor in a closed system to obtain acid-modified acetylene black. Sublimed sulfur that had been sieved was mixed with acid-modified acetylene black and ball-milled at 250-350 r / min for 9-11 hours to obtain a mixture. The mixture was then heat-treated at 150-160℃ for 11-13 hours under a nitrogen atmosphere to obtain modified acetylene black.

10. A method for preparing a base-coated copper foil to improve the cycling performance of silicon-oxygen materials according to claim 9, characterized in that: The sublimed sulfur and acid-modified acetylene black are mixed at a mass ratio of 14:6.

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