A solid-state battery based on a silicon-based negative electrode sheet and a preparation method thereof

Abstract

This invention discloses a solid-state battery based on a silicon-based anode sheet and its fabrication method, relating to the field of silicon-based anode sheet technology. The fabrication method is as follows: In an argon atmosphere, a positive electrode sheet, a first solid electrolyte layer, a silicon-based anode sheet, and a second solid electrolyte layer are sequentially stacked and aligned. A winding machine is used to wind the layers, ensuring no interlayer misalignment through positioning by winding needles and synchronous correction of the electrode sheet and the two solid electrolyte layers, thus obtaining a core. A metal core rod is inserted into the core, with both ends extending beyond the core body. The entire assembly is then inserted into the battery casing, compressing the two ends of the metal core rod extending beyond the core body to the height of the positive electrode sheet. The core is then welded together and sealed to obtain the solid-state battery. This invention solves the problems of volume expansion, poor conductivity, and interface instability in silicon-based anode sheets through the synergistic effect of multiple components. The battery exhibits high capacity, long cycle life, and high rate performance, showing broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of silicon-based anode technology, specifically to a solid-state battery based on a silicon-based anode and its fabrication method. Background Technology

[0002] Silicon-based anodes, due to their significantly higher theoretical specific capacity compared to traditional graphite anodes, have become a core candidate material for improving the energy density of solid-state batteries, showing broad application prospects in fields such as new energy vehicles and portable electronic devices. However, their actual industrialization faces multiple technical bottlenecks: the volume expansion rate during lithiation exceeds 300%, leading to electrode cracking, active material shedding, and damage to the battery's structural integrity; silicon itself has extremely low electronic and ionic conductivity, severely limiting charge transport efficiency and resulting in poor rate performance; the electrode-solid electrolyte interface is prone to chemical reactions, forming an unstable solid electrolyte interphase (SEI) film, and repeated cracking and repair consume a large number of lithium ions, causing rapid degradation of cycle performance. Existing modification schemes are mostly single strategies, such as simple carbon coating which only improves conductivity, and ordinary binders which only improve mechanical stability, which cannot simultaneously solve the above problems and cannot meet the comprehensive requirements of solid-state batteries for high capacity, long cycle life, high rate performance, and high safety, seriously hindering the commercialization process of silicon-based anode solid-state batteries.

[0003] Therefore, there is an urgent need to invent a solid-state battery based on silicon-based negative electrode sheets. Summary of the Invention

[0004] The purpose of this invention is to provide a solid-state battery based on a silicon-based negative electrode and its preparation method, so as to solve the problems raised in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for preparing a solid-state battery based on a silicon-based negative electrode includes the following steps: S1: Positive electrode preparation: lithium nickel cobalt manganese oxide, conductive carbon black and polyvinylidene fluoride are added to a reaction vessel, N-methylpyrrolidone is added, and the mixture is stirred evenly to obtain a positive electrode slurry; the positive electrode slurry is coated on an aluminum foil, vacuum dried at 120-150℃ for 8-12 hours, and rolled to obtain a positive electrode sheet;

[0007] S2: Preparation of solid electrolyte layer: Li6PS5Cl solid electrolyte is pressed into a thin film and vacuum annealed at 150-200℃ for 2-3 hours to obtain solid electrolyte layer;

[0008] S3: Solid-state battery assembly: In an argon atmosphere, the positive electrode, the first solid electrolyte layer, the silicon-based negative electrode, and the second solid electrolyte layer are sequentially stacked and aligned. The layers are wound using a winding machine. Positioning is achieved through winding needles, and the electrode and the two solid electrolyte layers are synchronously corrected to ensure no misalignment between layers, resulting in a core. A metal core rod is inserted into the core, with both ends of the metal core rod extending beyond the core body. The entire assembly is then inserted into the battery casing, and the two ends of the metal core rod extending beyond the core body are compressed to the height of the positive electrode. The core is then welded together and sealed to obtain a solid-state battery.

[0009] In the preparation of the positive electrode sheet, the proportions of each component by mass fraction are as follows: lithium nickel cobalt manganese oxide 90-95%, conductive carbon black 3-5%, polyvinylidene fluoride 2-5%; the concentration of the positive electrode slurry is 40-50 wt%.

[0010] Furthermore, the preparation method of the silicon-based negative electrode includes the following steps: Step 1: Pretreatment of nano-silicon: Add nano-silicon to anhydrous ethanol, ultrasonically disperse for 30-60 min, and vacuum dry at 80-100℃ for 2-4 h to obtain pretreated nano-silicon;

[0011] Step 2: Dual-carbon network coating: Add the dual-carbon network to anhydrous ethanol and ultrasonically disperse for 1-2 hours to obtain a dual-carbon network dispersion; add pretreated nano-silicon to the dual-carbon network dispersion, heat to 60-80℃ and stir for 2-3 hours, spray dry the particles to obtain silicon-dual-carbon network composite particles.

[0012] Step 3: Solid electrolyte coating: Add Li6PS5Cl solid electrolyte to anhydrous ethanol and ultrasonically disperse for 30-40 min to obtain solid electrolyte dispersion; add silicon-double carbon network composite particles to solid electrolyte dispersion, heat to 80-90℃ and stir for 1-2 h, and vacuum dry at 100-120℃ to obtain silicon-double carbon network-solid electrolyte composite particles.

[0013] Step 4: Preparation of composite adhesive: Polyethylene glycol bismaleate, polyacrylic acid-silk fibroin complex and lithium nanographene are added to deionized water and stirred and dispersed for 1-2 hours to obtain composite adhesive solution;

[0014] Step 5: Add silicon-double carbon network-solid electrolyte composite particles to the composite binder solution and stir for 30-60 minutes to obtain electrode slurry; coat the electrode slurry onto copper foil, vacuum dry at 80-100℃ for 6-8 hours, calcine at 200-300℃ in argon for 3-5 hours, cool and roll to obtain silicon-based negative electrode sheet.

[0015] Furthermore, in the preparation process of the silicon-based negative electrode, the proportions of each component by mass are as follows: 50-70 parts of nano-silicon, 5-13 parts of dual carbon network, 10-15 parts of Li6PS5Cl solid electrolyte, and 7-11 parts of composite binder; the coating thickness of the electrode slurry is 50-80 μm; and the thickness after cooling and rolling is 20-40 μm.

[0016] Furthermore, in the preparation process of the silicon-dual-carbon network composite particles, the dual-carbon network is composed of graphene nanosheets and carbon nanotubes; the mass ratio of graphene nanosheets to carbon nanotubes is (1.5-3):1; the concentration of the dual-carbon network dispersion is 15-50 mg / mL; and the mass-volume ratio of pretreated nano-silicon to dual-carbon network dispersion is 1 g:(10-20) mL.

[0017] Furthermore, in the preparation process of the silicon-dual-carbon network-solid electrolyte composite particles, the concentration of the solid electrolyte dispersion is 100-150 mg / mL; the mass-volume ratio of silicon-dual-carbon network composite particles to solid electrolyte dispersion is 1 g:(5-10) mL.

[0018] Furthermore, in the preparation process of the composite adhesive, the mass ratio of polyethylene glycol bismaleate: polyacrylic acid-silk fibroin complex: lithium nanographene is (3-5):(3-4):(1-2); the concentration of the composite adhesive solution is 5-8 wt%.

[0019] Furthermore, the preparation method of the polyacrylic acid-silk fibroin complex includes the following steps: adding polyacrylic acid and silk fibroin into a reaction vessel, heating to 60-80℃ and stirring for 2-3 hours to obtain the polyacrylic acid-silk fibroin complex;

[0020] In the preparation of the polyacrylic acid-silk fibroin complex, the mass ratio of polyacrylic acid to silk fibroin is (6-8):(2-4).

[0021] Furthermore, the preparation method of the lithium nanographene includes the following steps: adding graphene nanosheets to a mixed solution of concentrated sulfuric acid and nitric acid with a volume ratio of 3:1, ultrasonically dispersing for 1-1.5 h, heating to 110-115℃ and reacting for 23-24 h, rotary evaporation, adding 0.5-0.6 mol / L lithium carbonate solution, adding ethanol to precipitate, centrifuging, and vacuum drying to obtain lithium nanographene.

[0022] Furthermore, the thickness of the solid electrolyte layer is 50-100 μm; the metal core rod is made of any one of aluminum, titanium alloy, or stainless steel.

[0023] Furthermore, the battery casing is made of any one of stainless steel, titanium alloy, or engineering plastic.

[0024] Furthermore, the diameter of the metal core rod is d1, where d1 = core diameter d0 - (0.2 - 0.5), and the unit is mm;

[0025] Furthermore, the height of the positive electrode sheet is h0, the diameter of the compressed core is d2, and the core height = h1 is (π(d2 / 2)). 2 ×80) / (π(d0 / 2) 2 × Correction factor, in mm.

[0026] Furthermore, the polyacrylic acid has a molecular weight of 450,000-500,000 g / mol and a solid content of 5-8 wt%.

[0027] Furthermore, the nano-silicon particles have a diameter of 50-200 nm;

[0028] Furthermore, the graphene nanosheets have a thickness of 1-5 nm and a lateral dimension of 5-10 μm; the carbon nanotubes are single-walled or multi-walled carbon nanotubes with a diameter of 5-20 nm and a length of 1-5 μm.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. This invention utilizes a multi-layered synergistic system of nano-silicon, dual-carbon network, solid electrolyte and composite binder. The components do not act in isolation, but rather work together to form multiple synergistic effects such as conductivity, ion transport, mechanical stability and interface protection.

[0031] 2. The dual-carbon network in this invention forms a three-dimensional electronic conduction pathway with lithium nano-graphene, completely encapsulating the nano-silicon particles and connecting them to the current collector, greatly improving the conductivity. The solid electrolyte and the composite binder form a dual ion transport network. The solid electrolyte provides long-range ion conduction, while the ether bonds of the composite binder and the β-sheet conformation of silk fibroin provide short-range ion transport, synergistically greatly improving the diffusion coefficient of lithium ions. At the same time, the electronic and ion conduction pathways are intertwined, ensuring rapid insertion and extraction of lithium ions on the silicon surface, while electrons are transported rapidly, improving the rate performance of the solid-state battery.

[0032] 3. In this invention, the size effect of nano-silicon disperses the volume expansion stress, avoiding stress concentration in micron-sized silicon, thus forming a primary buffer; the spherical structure of the dual-carbon network has reserved pores inside, providing buffer space for volume expansion during the silicon lithiation reaction, thus forming a secondary buffer; the rigid coating layer of the solid electrolyte restricts excessive expansion of silicon particles, and the high cohesive strength and high adhesion of the composite binder firmly combine silicon, carbon network, and electrolyte, forming a mechanically stable system of rigid constraint and flexible buffer to synergistically suppress volume expansion, avoiding electrode cracking and active material shedding, thus forming a tertiary constraint.

[0033] 4. In this invention, the uniform coating of the solid electrolyte prevents direct contact between silicon and the electrolyte, reducing the exposure of fresh silicon surface and avoiding repeated rupture and repair of the SEI film; the solid electrolyte forms a stable interfacial phase with the silicon surface, further inhibiting the decomposition reaction between silicon and electrolyte; at the same time, the polar groups of the composite binder are adsorbed on the silicon surface, regulating the composition of the SEI film and forming a thin and stable SEI layer; finally, the synergistic effect of the dual carbon network and the binder disperses interfacial stress, preventing the SEI film from rupturing due to mechanical stress, and further improving interfacial stability. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1: A method for preparing a solid-state battery based on a silicon-based negative electrode, comprising the following steps: S1: 6g of polyacrylic acid and 2g of silk fibroin are added to a reaction vessel, heated to 70°C and stirred for 2.5h to obtain a polyacrylic acid-silk fibroin composite.

[0036] S2: Graphene nanosheets were added to a mixed solution of concentrated sulfuric acid and nitric acid in a volume ratio of 3:1, ultrasonically dispersed for 1 h, heated to 110℃ and reacted for 24 h, rotary evaporated, 0.5 mol / L lithium carbonate solution was added, ethanol was added to precipitate, centrifuged, and vacuum dried to obtain lithium nanographene.

[0037] S3: Preparation of silicon-based negative electrode: Step 1: Pretreatment of nano-silicon: Add 5g of nano-silicon to anhydrous ethanol, ultrasonically disperse for 30min, and vacuum dry at 80℃ for 2h to obtain pretreated nano-silicon;

[0038] Step 2: Dual-carbon network coating: 0.78g of graphene nanosheets and 0.52g of carbon nanotubes were added to 30mL of anhydrous ethanol and ultrasonically dispersed for 1.5h to obtain a dual-carbon network dispersion; 5g of pretreated nano-silicon was added to 50mL of dual-carbon network dispersion, heated to 70℃ and stirred for 2h, and the particles were spray-dried to obtain silicon-dual-carbon network composite particles.

[0039] Step 3: Solid electrolyte coating: 1.5g of Li6PS5Cl solid electrolyte was added to 1000mL of anhydrous ethanol and ultrasonically dispersed for 35min to obtain a 150mg / mL solid electrolyte dispersion; silicon-double carbon network composite particles were added to the solid electrolyte dispersion, heated to 85℃ and stirred for 1h, and then vacuum dried at 100℃ to obtain silicon-double carbon network-solid electrolyte composite particles;

[0040] Step 4: Preparation of composite adhesive: Add 0.3g of polyethylene glycol bismaleate, 0.3g of polyacrylic acid-silk fibroin complex and 0.1g of lithium nanographene to deionized water and stir to disperse for 1h to obtain a 6wt% composite adhesive solution;

[0041] Step 5: Add silicon-double carbon network-solid electrolyte composite particles to composite binder solution and stir for 45 min to obtain electrode slurry; coat the electrode slurry onto copper foil with a coating thickness of 50 μm, vacuum dry at 80℃ for 6 h, calcine at 200℃ in argon for 5 h, and roll to 20 μm after cooling to obtain silicon-based negative electrode sheet.

[0042] S4: Positive electrode preparation: 9g of lithium nickel cobalt manganese oxide, 0.5g of conductive carbon black and 0.5g of polyvinylidene fluoride were added to a reaction vessel, N-methylpyrrolidone was added, and the mixture was stirred evenly to obtain a 45wt% positive electrode slurry; the positive electrode slurry was coated on aluminum foil with a coating thickness of 50μm, vacuum dried at 120℃ for 8h, and rolled to a thickness of 20μm to obtain a positive electrode sheet;

[0043] S5: Preparation of solid electrolyte layer: Li6PS5Cl solid electrolyte was made into a thin film and vacuum annealed at 150℃ for 2h to obtain a solid electrolyte layer with a thickness of 50μm;

[0044] S6: Solid-state battery assembly: In an argon atmosphere, the positive electrode, solid electrolyte layer, silicon-based negative electrode, and solid electrolyte layer are sequentially stacked and aligned. The layers are wound using a winding machine. Positioning is achieved through winding needles, and synchronous correction of the electrode and solid electrolyte layers ensures no interlayer misalignment, resulting in a core. An aluminum metal core rod is inserted into the core, with both ends of the aluminum metal core rod extending beyond the core body. The entire assembly is then inserted into an engineering plastic battery casing. The two ends of the metal core rod extending beyond the core body are compressed to the height of the positive electrode, and the current is combined, welded, and sealed to obtain a solid-state battery.

[0045] The thickness of the solid electrolyte layer is 50 μm; the diameter of the metal core rod is d1 = 4.5 mm, the diameter of the wound core is d0 = 5 mm, the height of the positive electrode is h0 = 80 mm, the diameter of the wound core after compression is d2 = 5.5 mm, and the height of the wound core is h1 = (π(5.5 / 2)). 2 ×80) / (π(5 / 2) 2 × Correction factor, in mm.

[0046] Example 2: A method for preparing a solid-state battery based on a silicon-based negative electrode, comprising the following steps: S1: 7g of polyacrylic acid and 3g of silk fibroin are added to a reaction vessel, heated to 70°C and stirred for 2.5h to obtain a polyacrylic acid-silk fibroin composite.

[0047] S2: Graphene nanosheets were added to a mixed solution of concentrated sulfuric acid and nitric acid in a volume ratio of 3:1, ultrasonically dispersed for 1 h, heated to 110℃ and reacted for 24 h, rotary evaporated, 0.5 mol / L lithium carbonate solution was added, ethanol was added to precipitate, centrifuged, and vacuum dried to obtain lithium nanographene.

[0048] S3: Preparation of silicon-based negative electrode: Step 1: Pretreatment of nano-silicon: Add 6g of nano-silicon to anhydrous ethanol, ultrasonically disperse for 30min, and vacuum dry at 80℃ for 2h to obtain pretreated nano-silicon;

[0049] Step 2: Dual-carbon network coating: Add 0.6g of graphene nanosheets and 0.3g of carbon nanotubes to 30mL of anhydrous ethanol and ultrasonically disperse for 1.5h to obtain a dual-carbon network dispersion; add 6g of pretreated nano-silicon to 60mL of dual-carbon network dispersion, heat to 70℃ and stir for 2h, spray dry the particles to obtain silicon-dual-carbon network composite particles.

[0050] Step 3: Solid electrolyte coating: 1.2g of Li6PS5Cl solid electrolyte was added to 1000mL of anhydrous ethanol and ultrasonically dispersed for 35min to obtain a 120mg / mL solid electrolyte dispersion; silicon-double carbon network composite particles were added to the solid electrolyte dispersion, heated to 85℃ and stirred for 1h, and then vacuum dried at 100℃ to obtain silicon-double carbon network-solid electrolyte composite particles;

[0051] Step 4: Preparation of composite adhesive: Add 0.4g of polyethylene glycol bismaleate, 0.35g of polyacrylic acid-silk fibroin complex and 0.15g of lithium nanographene to deionized water and stir to disperse for 1h to obtain a 6wt% composite adhesive solution.

[0052] Step 5: Add silicon-double carbon network-solid electrolyte composite particles to composite binder solution and stir for 45 min to obtain electrode slurry; coat the electrode slurry onto copper foil with a coating thickness of 50 μm, vacuum dry at 80℃ for 6 h, calcine at 200℃ in argon for 5 h, and roll to 20 μm after cooling to obtain silicon-based negative electrode sheet.

[0053] S4: Positive electrode preparation: 9.2g of lithium nickel cobalt manganese oxide, 0.4g of conductive carbon black and 0.4g of polyvinylidene fluoride were added to a reaction vessel, N-methylpyrrolidone was added, and the mixture was stirred evenly to obtain a 45wt% positive electrode slurry; the positive electrode slurry was coated on aluminum foil with a coating thickness of 50μm, vacuum dried at 120℃ for 8h, and rolled to a thickness of 20μm to obtain a positive electrode sheet;

[0054] S5: Preparation of solid electrolyte layer: Li6PS5Cl solid electrolyte was pressed into a thin film and vacuum annealed at 150℃ for 2h to obtain a solid electrolyte layer with a thickness of 50μm;

[0055] S6: Solid-state battery assembly: In an argon atmosphere, the positive electrode, solid electrolyte layer, silicon-based negative electrode, and solid electrolyte layer are sequentially stacked and aligned. The layers are wound using a winding machine. Positioning is achieved through winding needles, and synchronous correction of the electrode and solid electrolyte layers ensures no interlayer misalignment, resulting in a core. An aluminum metal core rod is inserted into the core, with both ends of the aluminum metal core rod extending beyond the core body. The entire assembly is then inserted into an engineering plastic battery casing. The two ends of the metal core rod extending beyond the core body are compressed to the height of the positive electrode, and the current is combined, welded, and sealed to obtain a solid-state battery.

[0056] The thickness of the solid electrolyte layer is 50 μm; the diameter of the metal core rod is d1 = 4.5 mm, the diameter of the wound core is d0 = 5 mm, the height of the positive electrode is h0 = 80 mm, the diameter of the wound core after compression is d2 = 5.5 mm, and the height of the wound core is h1 = (π(5.5 / 2)). 2 ×80) / (π(5 / 2) 2 × Correction factor, in mm.

[0057] Example 3: A method for preparing a solid-state battery based on a silicon-based negative electrode, comprising the following steps: S1: 8g of polyacrylic acid and 4g of silk fibroin are added to a reaction vessel, heated to 70°C and stirred for 2.5h to obtain a polyacrylic acid-silk fibroin composite.

[0058] S2: Graphene nanosheets were added to a mixed solution of concentrated sulfuric acid and nitric acid in a volume ratio of 3:1, ultrasonically dispersed for 1 h, heated to 110 °C and reacted for 24 h, rotary evaporated, 0.6 mol / L lithium carbonate solution was added, ethanol was added to precipitate, centrifuged, and vacuum dried to obtain lithium-ion graphene nanosheets.

[0059] S3: Preparation of silicon-based negative electrode: Step 1: Pretreatment of nano-silicon: Add 7g of nano-silicon to anhydrous ethanol, ultrasonically disperse for 30min, and vacuum dry at 80℃ for 2h to obtain pretreated nano-silicon;

[0060] Step 2: Dual-carbon network coating: 0.375g of graphene nanosheets and 0.125g of carbon nanotubes were added to 30mL of anhydrous ethanol and ultrasonically dispersed for 1.5h to obtain a dual-carbon network dispersion; 7g of pretreated nano-silicon was added to 70mL of the dual-carbon network dispersion, heated to 70℃ and stirred for 2h, and the particles were spray-dried to obtain silicon-dual-carbon network composite particles.

[0061] Step 3: Solid electrolyte coating: Add 1g of Li6PS5Cl solid electrolyte to 1000mL of anhydrous ethanol and sonicate for 35min to obtain a 100mg / mL solid electrolyte dispersion; add silicon-double carbon network composite particles to the solid electrolyte dispersion, heat to 85℃ and stir for 1h, and dry under vacuum at 100℃ to obtain silicon-double carbon network-solid electrolyte composite particles.

[0062] Step 4: Preparation of composite adhesive: Add 0.5g of polyethylene glycol bismaleate, 0.4g of polyacrylic acid-silk fibroin complex and 0.2g of lithium nanographene to deionized water and stir to disperse for 1h to obtain a 6wt% composite adhesive solution;

[0063] Step 5: Add silicon-double carbon network-solid electrolyte composite particles to composite binder solution and stir for 45 min to obtain electrode slurry; coat the electrode slurry onto copper foil with a coating thickness of 50 μm, vacuum dry at 80℃ for 6 h, calcine at 200℃ in argon for 5 h, and roll to 20 μm after cooling to obtain silicon-based negative electrode sheet.

[0064] S4: Positive electrode preparation: 9.5g of lithium nickel cobalt manganese oxide, 0.3g of conductive carbon black and 0.2g of polyvinylidene fluoride were added to a reaction vessel, N-methylpyrrolidone was added, and the mixture was stirred evenly to obtain a 45wt% positive electrode slurry; the positive electrode slurry was coated on aluminum foil with a coating thickness of 50μm, vacuum dried at 120℃ for 8h, and rolled to a thickness of 20μm to obtain a positive electrode sheet;

[0065] S5: Preparation of solid electrolyte layer: Li6PS5Cl solid electrolyte was made into a thin film and vacuum annealed at 150℃ for 2h to obtain a solid electrolyte layer with a thickness of 50μm;

[0066] S6: Solid-state battery assembly: In an argon atmosphere, the positive electrode, solid electrolyte layer, silicon-based negative electrode, and solid electrolyte layer are sequentially stacked and aligned. The layers are wound using a winding machine. Positioning is achieved through winding needles, and synchronous correction of the electrode and solid electrolyte layers ensures no interlayer misalignment, resulting in a core. An aluminum metal core rod is inserted into the core, with both ends of the aluminum metal core rod extending beyond the core body. The entire assembly is then inserted into an engineering plastic battery casing. The two ends of the metal core rod extending beyond the core body are compressed to the height of the positive electrode, and the current is combined, welded, and sealed to obtain a solid-state battery.

[0067] The thickness of the solid electrolyte layer is 50 μm; the diameter of the metal core rod is d1 = 4.5 mm, the diameter of the wound core is d0 = 5 mm, the height of the positive electrode is h0 = 80 mm, the diameter of the wound core after compression is d2 = 5.5 mm, and the height of the wound core is h1 = (π(5.5 / 2)). 2 ×80) / (π(5 / 2) 2 × Correction factor, in mm.

[0068] Comparative Example 1: A method for preparing a solid-state battery based on a silicon-based negative electrode, comprising the following steps: S1: 6g of polyacrylic acid and 2g of silk fibroin are added to a reaction vessel, heated to 70°C and stirred for 2.5h to obtain a polyacrylic acid-silk fibroin composite.

[0069] S2: Graphene nanosheets were added to a mixed solution of concentrated sulfuric acid and nitric acid in a volume ratio of 3:1, ultrasonically dispersed for 1 h, heated to 110℃ and reacted for 24 h, rotary evaporated, 0.5 mol / L lithium carbonate solution was added, ethanol was added to precipitate, centrifuged, and vacuum dried to obtain lithium nanographene.

[0070] S3: Preparation of silicon-based negative electrode: Step 1: Pretreatment of nano-silicon: Add 6g of nano-silicon to anhydrous ethanol, ultrasonically disperse for 30min, and vacuum dry at 80℃ for 2h to obtain pretreated nano-silicon;

[0071] Step 2: Preparation of composite adhesive: Add 0.4g of polyethylene glycol bismaleate, 0.35g of polyacrylic acid-silk fibroin complex and 0.15g of lithium nanographene to deionized water and stir to disperse for 1h to obtain a 6wt% composite adhesive solution;

[0072] Step 3: Add 1.2g of Li6PS5Cl solid electrolyte to the composite binder solution and stir for 45min to obtain electrode slurry; coat the electrode slurry onto copper foil with a coating thickness of 50μm, vacuum dry at 80℃ for 6h, calcine at 200℃ under argon for 5h, and roll to 20μm after cooling to obtain silicon-based negative electrode sheet.

[0073] S4: Positive electrode preparation: 9g of lithium nickel cobalt manganese oxide, 0.5g of conductive carbon black and 0.5g of polyvinylidene fluoride were added to a reaction vessel, N-methylpyrrolidone was added, and the mixture was stirred evenly to obtain a 45wt% positive electrode slurry; the positive electrode slurry was coated on aluminum foil with a coating thickness of 50μm, vacuum dried at 120℃ for 8h, and rolled to a thickness of 20μm to obtain a positive electrode sheet;

[0074] S5: Preparation of solid electrolyte layer: Li6PS5Cl solid electrolyte was pressed into a thin film and vacuum annealed at 150℃ for 2h to obtain a solid electrolyte layer with a thickness of 50μm;

[0075] S6: Solid-state battery assembly: In an argon atmosphere, the positive electrode, solid electrolyte layer, silicon-based negative electrode, and solid electrolyte layer are sequentially stacked and aligned. The layers are wound using a winding machine. Positioning is achieved through winding needles, and synchronous correction of the electrode and solid electrolyte layers ensures no interlayer misalignment, resulting in a core. An aluminum metal core rod is inserted into the core, with both ends of the aluminum metal core rod extending beyond the core body. The entire assembly is then inserted into an engineering plastic battery casing. The two ends of the metal core rod extending beyond the core body are compressed to the height of the positive electrode, and the current is combined, welded, and sealed to obtain a solid-state battery.

[0076] The thickness of the solid electrolyte layer is 50 μm; the diameter of the metal core rod is d1 = 4.5 mm, the diameter of the wound core is d0 = 5 mm, the height of the positive electrode is h0 = 80 mm, the diameter of the wound core after compression is d2 = 5.5 mm, and the height of the wound core is h1 = (π(5.5 / 2)). 2×80) / (π(5 / 2) 2 × Correction factor, in mm.

[0077] Comparative Example 2: A method for preparing a solid-state battery based on a silicon-based negative electrode, comprising the following steps: S1: 7g of polyacrylic acid and 3g of silk fibroin are added to a reaction vessel, heated to 70°C and stirred for 2.5h to obtain a polyacrylic acid-silk fibroin composite.

[0078] S2: Graphene nanosheets were added to a mixed solution of concentrated sulfuric acid and nitric acid in a volume ratio of 3:1, ultrasonically dispersed for 1 h, heated to 110℃ and reacted for 24 h, rotary evaporated, 0.5 mol / L lithium carbonate solution was added, ethanol was added to precipitate, centrifuged, and vacuum dried to obtain lithium nanographene.

[0079] S3: Preparation of silicon-based negative electrode: Step 1: Pretreatment of nano-silicon: Add 6g of nano-silicon to anhydrous ethanol, ultrasonically disperse for 30min, and vacuum dry at 80℃ for 2h to obtain pretreated nano-silicon;

[0080] Step 2: Dual-carbon network coating: Add 0.6g of graphene nanosheets and 0.3g of carbon nanotubes to 30mL of anhydrous ethanol and ultrasonically disperse for 1.5h to obtain a dual-carbon network dispersion; add 6g of pretreated nano-silicon to 60mL of dual-carbon network dispersion, heat to 70℃ and stir for 2h, spray dry the particles to obtain silicon-dual-carbon network composite particles.

[0081] Step 3: Solid electrolyte coating: 1.2g of Li6PS5Cl solid electrolyte was added to 1000mL of anhydrous ethanol and ultrasonically dispersed for 35min to obtain a 120mg / mL solid electrolyte dispersion; silicon-double carbon network composite particles were added to the solid electrolyte dispersion, heated to 85℃ and stirred for 1h, and then vacuum dried at 100℃ to obtain silicon-double carbon network-solid electrolyte composite particles;

[0082] Step 4: Preparation of composite adhesive: Add aqueous acrylic acid to deionized water and stir to disperse for 1 hour to obtain a 6wt% composite adhesive solution;

[0083] Step 5: Add silicon-double carbon network-solid electrolyte composite particles to composite binder solution and stir for 45 min to obtain electrode slurry; coat the electrode slurry onto copper foil with a coating thickness of 50 μm, vacuum dry at 80℃ for 6 h, calcine at 200℃ in argon for 5 h, and roll to 20 μm after cooling to obtain silicon-based negative electrode sheet.

[0084] S4: Positive electrode preparation: 9.2g of lithium nickel cobalt manganese oxide, 0.4g of conductive carbon black and 0.4g of polyvinylidene fluoride were added to a reaction vessel, N-methylpyrrolidone was added, and the mixture was stirred evenly to obtain a 45wt% positive electrode slurry; the positive electrode slurry was coated on aluminum foil with a coating thickness of 50μm, vacuum dried at 120℃ for 8h, and rolled to a thickness of 20μm to obtain a positive electrode sheet;

[0085] S5: Preparation of solid electrolyte layer: Li6PS5Cl solid electrolyte was pressed into a thin film and vacuum annealed at 150℃ for 2h to obtain a solid electrolyte layer with a thickness of 50μm;

[0086] S6: Solid-state battery assembly: In an argon atmosphere, the positive electrode, solid electrolyte layer, silicon-based negative electrode, and solid electrolyte layer are sequentially stacked and aligned. The layers are wound using a winding machine. Positioning is achieved through winding needles, and synchronous correction of the electrode and solid electrolyte layers ensures no interlayer misalignment, resulting in a core. An aluminum metal core rod is inserted into the core, with both ends of the aluminum metal core rod extending beyond the core body. The entire assembly is then inserted into an engineering plastic battery casing. The two ends of the metal core rod extending beyond the core body are compressed to the height of the positive electrode, and the current is combined, welded, and sealed to obtain a solid-state battery.

[0087] The thickness of the solid electrolyte layer is 50 μm; the diameter of the metal core rod is d1 = 4.5 mm, the diameter of the wound core is d0 = 5 mm, the height of the positive electrode is h0 = 80 mm, the diameter of the wound core after compression is d2 = 5.5 mm, and the height of the wound core is h1 = (π(5.5 / 2)). 2 ×80) / (π(5 / 2) 2 × Correction factor, in mm.

[0088] Comparative Example 3: A method for preparing a solid-state battery based on a silicon-based negative electrode, comprising the following steps: S1: 7g of polyacrylic acid and 3g of silk fibroin are added to a reaction vessel, heated to 70°C and stirred for 2.5h to obtain a polyacrylic acid-silk fibroin composite.

[0089] S2: Graphene nanosheets were added to a mixed solution of concentrated sulfuric acid and nitric acid in a volume ratio of 3:1, ultrasonically dispersed for 1 h, heated to 110℃ and reacted for 24 h, rotary evaporated, 0.5 mol / L lithium carbonate solution was added, ethanol was added to precipitate, centrifuged, and vacuum dried to obtain lithium nanographene.

[0090] S3: Preparation of silicon-based negative electrode: Step 1: Pretreatment of nano-silicon: Add 6g of nano-silicon to anhydrous ethanol, ultrasonically disperse for 30min, and vacuum dry at 80℃ for 2h to obtain pretreated nano-silicon;

[0091] Step 2: Dual-carbon network coating: Add 0.6g of graphene nanosheets and 0.3g of carbon nanotubes to 30mL of anhydrous ethanol and ultrasonically disperse for 1.5h to obtain a dual-carbon network dispersion; add 6g of pretreated nano-silicon to 60mL of dual-carbon network dispersion, heat to 70℃ and stir for 2h, spray dry the particles to obtain silicon-dual-carbon network composite particles.

[0092] Step 3: Preparation of composite adhesive: Add 0.4g of polyethylene glycol bismaleate, 0.35g of polyacrylic acid-silk fibroin complex and 0.15g of lithium nanographene to deionized water and stir to disperse for 1h to obtain a 6wt% composite adhesive solution;

[0093] Step 4: Add 1.2g of Li6PS5Cl solid electrolyte and 0.9g of silicon-double carbon network composite particles to the composite binder solution, stir and mix for 45min to obtain electrode slurry; coat the electrode slurry onto copper foil with a coating thickness of 50μm, vacuum dry at 80℃ for 6h, calcine at 200℃ under argon for 5h, cool and roll to 20μm to obtain silicon-based negative electrode sheet.

[0094] S4: Positive electrode preparation: 9.2g of lithium nickel cobalt manganese oxide, 0.4g of conductive carbon black and 0.4g of polyvinylidene fluoride were added to a reaction vessel, N-methylpyrrolidone was added, and the mixture was stirred evenly to obtain a positive electrode slurry; the positive electrode slurry was coated on aluminum foil with a coating thickness of 50μm, vacuum dried at 120℃ for 8h, and rolled to a thickness of 20μm to obtain a positive electrode sheet;

[0095] S5: Preparation of solid electrolyte layer: Li6PS5Cl solid electrolyte was pressed into a thin film and vacuum annealed at 150℃ for 2h to obtain a solid electrolyte layer with a thickness of 50μm;

[0096] S6: Solid-state battery assembly: In an argon atmosphere, the positive electrode, solid electrolyte layer, silicon-based negative electrode, and solid electrolyte layer are sequentially stacked and aligned. The layers are wound using a winding machine. Positioning is achieved through winding needles, and synchronous correction of the electrode and solid electrolyte layers ensures no interlayer misalignment, resulting in a core. An aluminum metal core rod is inserted into the core, with both ends of the aluminum metal core rod extending beyond the core body. The entire assembly is then inserted into an engineering plastic battery casing. The two ends of the metal core rod extending beyond the core body are compressed to the height of the positive electrode, and the current is combined, welded, and sealed to obtain a solid-state battery.

[0097] The thickness of the solid electrolyte layer is 50 μm; the diameter of the metal core rod is d1 = 4.5 mm, the diameter of the wound core is d0 = 5 mm, the height of the positive electrode is h0 = 80 mm, the diameter of the wound core after compression is d2 = 5.5 mm, and the height of the wound core is h1 = (π(5.5 / 2)). 2 ×80) / (π(5 / 2) 2 × Correction factor, in mm.

[0098] Comparative Example 4: A method for preparing a solid-state battery based on a silicon-based negative electrode, comprising the following steps: S1: 7g of polyacrylic acid and 3g of silk fibroin are added to a reaction vessel, heated to 70°C and stirred for 2.5h to obtain a polyacrylic acid-silk fibroin composite.

[0099] S2: Graphene nanosheets were added to a mixed solution of concentrated sulfuric acid and nitric acid in a volume ratio of 3:1, ultrasonically dispersed for 1 h, heated to 110℃ and reacted for 24 h, rotary evaporated, 0.5 mol / L lithium carbonate solution was added, ethanol was added to precipitate, centrifuged, and vacuum dried to obtain lithium nanographene.

[0100] S3: Preparation of silicon-based negative electrode: Step 1: Pretreatment of micron-sized silicon: Add 6g of micron-sized silicon to anhydrous ethanol, ultrasonically disperse for 30min, and vacuum dry at 80℃ for 2h to obtain pretreated micron-sized silicon; the particle size of the micron-sized silicon is 5μm;

[0101] Step 2: Dual-carbon network coating: Add 0.6g of graphene nanosheets and 0.3g of carbon nanotubes to 30mL of anhydrous ethanol and ultrasonically disperse for 1.5h to obtain a dual-carbon network dispersion; add 6g of pretreated micron-sized silicon to 60mL of dual-carbon network dispersion, heat to 70℃ and stir for 2h, spray dry the particles to obtain silicon-dual-carbon network composite particles.

[0102] Step 3: Solid electrolyte coating: 1.2g of Li6PS5Cl solid electrolyte was added to 1000mL of anhydrous ethanol and ultrasonically dispersed for 35min to obtain a 120mg / mL solid electrolyte dispersion; silicon-double carbon network composite particles were added to the solid electrolyte dispersion, heated to 85℃ and stirred for 1h, and then vacuum dried at 100℃ to obtain silicon-double carbon network-solid electrolyte composite particles;

[0103] Step 4: Preparation of composite adhesive: Add 0.4 g of polyethylene glycol bismaleate, 0.35 g of polyacrylic acid-silk fibroin complex and 0.15 g of lithium nanographene to deionized water and stir to disperse for 1 h to obtain a 6 wt% composite adhesive solution.

[0104] Step 5: Add silicon-double carbon network-solid electrolyte composite particles to composite binder solution and stir for 45 min to obtain electrode slurry; coat the electrode slurry onto copper foil with a coating thickness of 50 μm, vacuum dry at 80℃ for 6 h, calcine at 200℃ in argon for 5 h, and roll to 20 μm after cooling to obtain silicon-based negative electrode sheet.

[0105] S4: Positive electrode preparation: 9.2g of lithium nickel cobalt manganese oxide, 0.4g of conductive carbon black and 0.4g of polyvinylidene fluoride were added to a reaction vessel, N-methylpyrrolidone was added, and the mixture was stirred evenly to obtain a 45wt% positive electrode slurry; the positive electrode slurry was coated on aluminum foil with a coating thickness of 50μm, vacuum dried at 120℃ for 8h, and rolled to a thickness of 20μm to obtain a positive electrode sheet;

[0106] S5: Preparation of solid electrolyte layer: Li6PS5Cl solid electrolyte was pressed into a thin film and vacuum annealed at 150℃ for 2h to obtain a solid electrolyte layer with a thickness of 50μm;

[0107] S6: Solid-state battery assembly: In an argon atmosphere, the positive electrode, solid electrolyte layer, silicon-based negative electrode, and solid electrolyte layer are sequentially stacked and aligned. The layers are wound using a winding machine. Positioning is achieved through winding needles, and synchronous correction of the electrode and solid electrolyte layers ensures no interlayer misalignment, resulting in a core. An aluminum metal core rod is inserted into the core, with both ends of the aluminum metal core rod extending beyond the core body. The entire assembly is then inserted into an engineering plastic battery casing. The two ends of the metal core rod extending beyond the core body are compressed to the height of the positive electrode, and the current is combined, welded, and sealed to obtain a solid-state battery.

[0108] The thickness of the solid electrolyte layer is 50 μm; the diameter of the metal core rod is d1 = 4.5 mm, the diameter of the wound core is d0 = 5 mm, the height of the positive electrode is h0 = 80 mm, the diameter of the wound core after compression is d2 = 5.5 mm, and the height of the wound core is h1 = (π(5.5 / 2)). 2 ×80) / (π(5 / 2) 2 × Correction factor, in mm.

[0109] Performance testing: Cyclic performance: Activated twice at 0.1C (280mA / g), and cycled 1000 times at 1C (2800mA / g) with a voltage range of 0.01-1.5V.

[0110] Rate performance: 5 cycles each at 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, and 10C, and the discharge capacity was recorded;

[0111] Coulomb efficiency: The average coulomb efficiency is calculated as the ratio of discharge capacity to charge capacity per cycle (100%).

[0112] Volume expansion rate: Electrode thickness before and after cycling was observed using scanning electron microscopy, (thickness after cycling - thickness before cycling) / thickness before cycling × 100%;

[0113] Electrode bond strength: universal testing machine 180° peel test, peel speed 200mm / min, record average peel force;

[0114] Electronic conductivity: Electrode electronic conductivity is tested using a four-probe tester;

[0115] Ionic conductivity: Ionic conductivity was calculated using the blocking cell method and impedance spectroscopy.

[0116] The test results are shown in Table 1 below.

[0117] Table 1. Performance Test Data of Solid-State Batteries and Active Materials

[0118]

[0119] Conclusion: Compared with comparative examples lacking a dual-carbon network and using a single binder, this invention fully demonstrates that the multi-layered synergistic system of nano-silicon, a dual-carbon network, a solid electrolyte, and a composite binder can effectively solve the core technical challenges of silicon-based anodes. This invention achieves a unified performance of high capacity, long cycle life, low expansion, and high rate capability, providing a reliable technical solution for the research and application of high-performance solid-state batteries.

[0120] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for fabricating a solid-state battery based on a silicon-based anode sheet, characterized in that: Includes the following steps: S1: Positive electrode preparation: Lithium nickel cobalt manganese oxide, conductive carbon black and polyvinylidene fluoride are added to a reaction vessel, N-methylpyrrolidone is added, and the mixture is stirred evenly to obtain a positive electrode slurry; the positive electrode slurry is coated on aluminum foil, vacuum dried, and rolled to obtain a positive electrode sheet; S2: Solid electrolyte layer preparation: Li6PS5Cl solid electrolyte is pressed into a thin film and vacuum annealed to obtain a solid electrolyte layer; S3: Solid-state battery assembly: In an argon atmosphere, the positive electrode, the first solid electrolyte layer, the silicon-based negative electrode, and the second solid electrolyte layer are sequentially stacked and aligned. The layers are wound using a winding machine. Positioning is achieved through winding needles, and the electrode and the two solid electrolyte layers are synchronously corrected to ensure no misalignment between layers, resulting in a core. A metal core rod is inserted into the core, with both ends of the metal core rod extending beyond the core body. The entire assembly is then inserted into the battery casing, and the two ends of the metal core rod extending beyond the core body are compressed to the height of the positive electrode. The core is then welded together and sealed to obtain a solid-state battery. In the preparation of the positive electrode, the proportions of each component by mass fraction are as follows: lithium nickel cobalt manganese oxide 90-95%, conductive carbon black 3-5%, polyvinylidene fluoride 2-5%; the concentration of the positive electrode slurry is 40-50 wt%. The method for preparing the silicon-based negative electrode includes the following steps: Step 1: Pretreatment of nano-silicon: Add nano-silicon to anhydrous ethanol, ultrasonically disperse for 30-60 min, and vacuum dry at 80-100℃ for 2-4 h to obtain pretreated nano-silicon; Step 2: Dual-carbon network coating: Add the dual-carbon network to anhydrous ethanol and ultrasonically disperse for 1-2 hours to obtain a dual-carbon network dispersion; add pretreated nano-silicon to the dual-carbon network dispersion, heat to 60-80℃ and stir for 2-3 hours, spray dry the particles to obtain silicon-dual-carbon network composite particles. Step 3: Solid electrolyte coating: Add Li6PS5Cl solid electrolyte to anhydrous ethanol and ultrasonically disperse for 30-40 min to obtain solid electrolyte dispersion; add silicon-double carbon network composite particles to solid electrolyte dispersion, heat to 80-90℃ and stir for 1-2 h, and vacuum dry at 100-120℃ to obtain silicon-double carbon network-solid electrolyte composite particles. Step 4: Preparation of composite adhesive: Polyethylene glycol bismaleate, polyacrylic acid-silk fibroin complex and lithium nanographene are added to deionized water and stirred and dispersed for 1-2 hours to obtain composite adhesive solution; Step 5: Add silicon-double carbon network-solid electrolyte composite particles to composite binder solution and stir for 30-60 min to obtain electrode slurry; coat electrode slurry onto copper foil, vacuum dry at 80-100℃ for 6-8 h, calcine at 200-300℃ in argon for 3-5 h, cool and roll press to obtain silicon-based negative electrode sheet; In the preparation process of silicon-dual carbon network composite particles, the dual carbon network is composed of graphene nanosheets and carbon nanotubes; The preparation method of the polyacrylic acid-silk fibroin complex includes the following steps: adding polyacrylic acid and silk fibroin into a reaction vessel, heating to 60-80℃ and stirring for 2-3 hours to obtain the polyacrylic acid-silk fibroin complex. The preparation method of the lithium nanographene includes the following steps: adding graphene nanosheets to a mixed solution of concentrated sulfuric acid and nitric acid with a volume ratio of 3:1, ultrasonically dispersing for 1-1.5 h, heating to 110-115℃ and reacting for 23-24 h, rotary evaporation, adding 0.5-0.6 mol / L lithium carbonate solution, adding ethanol to precipitate, centrifuging, and vacuum drying to obtain lithium nanographene.

2. The method for preparing a solid-state battery based on a silicon-based negative electrode according to claim 1, characterized in that: In the preparation of the silicon-based negative electrode, the proportions of each component by mass are as follows: 50-70 parts of nano-silicon, 5-13 parts of dual carbon network, 10-15 parts of Li6PS5Cl solid electrolyte, and 7-11 parts of composite binder; the coating thickness of the electrode slurry is 50-80 μm; and the thickness after cooling and rolling is 20-40 μm.

3. The method for fabricating a solid-state battery based on a silicon-based negative electrode according to claim 1, characterized in that: The mass ratio of graphene nanosheets to carbon nanotubes is (1.5-3):1; the concentration of the dual-carbon network dispersion is 15-50 mg / mL; the mass-volume ratio of pretreated nano-silicon to dual-carbon network dispersion is 1 g:(10-20) mL.

4. The method for fabricating a solid-state battery based on a silicon-based negative electrode according to claim 1, characterized in that: In the preparation of silicon-double carbon network-solid electrolyte composite particles, the concentration of the solid electrolyte dispersion is 100-150 mg / mL; the mass-volume ratio of silicon-double carbon network composite particles to solid electrolyte dispersion is 1 g:(5-10) mL.

5. The method for fabricating a solid-state battery based on a silicon-based negative electrode according to claim 1, characterized in that: In the preparation of the composite adhesive, the mass ratio of polyethylene glycol bismaleate: polyacrylic acid-silk fibroin complex: lithium nanographene is (3-5):(3-4):(1-2); the concentration of the composite adhesive solution is 5-8 wt%.

6. The method for preparing a solid-state battery based on a silicon-based negative electrode according to claim 1, characterized in that: In the preparation of the polyacrylic acid-silk fibroin complex, the mass ratio of polyacrylic acid to silk fibroin is (6-8):(2-4).

7. The method for preparing a solid-state battery based on a silicon-based negative electrode according to claim 1, characterized in that: The thickness of the solid electrolyte layer is 50-100μm; the metal core rod is made of any one of aluminum, titanium alloy, and stainless steel; the battery casing is made of any one of stainless steel, titanium alloy, and engineering plastic. The diameter of the metal core rod is d1, where d1 = core diameter d0 - (0.2 - 0.5), and the unit is mm; The height of the positive electrode sheet is h0, the diameter of the compressed core is d2, and the core height = h1 is (π(d2 / 2)). 2 ×80) / (π(d0 / 2) 2 × Correction factor, in mm.

8. A solid-state battery based on a silicon-based anode sheet prepared by the method for preparing a solid-state battery based on a silicon-based anode sheet according to any one of claims 1-7.

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