Positive plate with high interface infiltration and bonding performance, preparation method of positive plate and solid-state battery

Abstract

The invention provides a positive plate with high interface infiltration and bonding performance, a preparation method of the positive plate and a solid-state battery, and relates to the technical field of solid-state batteries. The positive plate comprises a current collector, a positive active layer and an interface function layer, the positive active layer and the interface functional layer are sequentially arranged on the front and back surfaces of the current collector; the raw material of the positive electrode active layer comprises a positive electrode active slurry; the raw material of the interface functional layer comprises a modification liquid; the raw material of the modification liquid comprises an infiltration modifier, a combination enhancer and a reaction inhibitor. The interface function layer formed by the technical scheme can effectively solve the problems that the wettability of an electrode-electrolyte interface is insufficient and the bonding force of a solid-solid bonding interface is weak, meanwhile, the occurrence of interface side reactions is inhibited, and the overall interface performance is improved.

Description

Technical Field

[0001] This application relates to the field of solid-state battery technology, and in particular to a positive electrode sheet with high interface wetting and bonding performance, its preparation method, and a solid-state battery. Background Technology

[0002] In the wet-process preparation of solid-state battery cathodes, insufficient interfacial wettability between the electrode and electrolyte is a key obstacle. Due to the generally low surface energy of the cathode and the relatively high surface energy of the solid electrolyte, a significant surface energy difference exists, making it difficult for the electrolyte to fully wet the electrode surface, resulting in numerous microscopic voids. This "point contact" phenomenon interrupts ion transport pathways, severely hindering the efficient migration of lithium ions. Simultaneously, the bonding between the active material, conductive agent, and binder within the cathode relies primarily on physical adsorption, resulting in weak interfacial adhesion. During battery charge-discharge cycles, the electrode material's slight volume expansion easily triggers interfacial separation and microcracks, further damaging the ion transport network and accelerating battery performance degradation. Furthermore, there is a risk of side reactions at the electrode-electrolyte interface, such as the interaction of transition metal ions with sulfide electrolytes to generate insulating byproducts, leading to a continuous increase in interfacial impedance. Existing technologies, some methods for improving the interface, require complex processes such as high-temperature sintering or precision deposition, which not only demand high-end equipment but are also incompatible with conventional wet coating production lines, significantly increasing manufacturing costs and limiting large-scale applications. Therefore, existing technologies urgently need improvement to address these issues. Summary of the Invention

[0003] The purpose of this application is to provide a positive electrode sheet with high interfacial wetting and bonding performance, a method for preparing the same, and a solid-state battery, in order to solve the above-mentioned problems.

[0004] To achieve the above objectives, this application adopts the following technical solution: This application provides a positive electrode sheet with high interfacial wetting and binding performance, including a current collector, a positive electrode active layer, and an interfacial functional layer; The positive electrode active layer and the interface functional layer are sequentially disposed on the front and back sides of the current collector; The raw materials for the positive electrode active layer include a positive electrode active slurry, and the raw materials for the positive electrode active slurry include a positive electrode active material, a conductive agent, a binder, and a polar organic solvent. The mass ratio of the positive electrode active material, the conductive agent, the binder, and the polar organic solvent is 80-90:2-5:3-7:8-15. The raw materials of the interface functional layer include a modified liquid, and the raw materials of the modified liquid include a wetting modifier, a binding enhancer, and a reaction inhibitor. The volume ratio of the wetting modifier, the binding enhancer, and the reaction inhibitor is 4-6:2-4:1-3. The raw materials of the wetting modifier include polyether compounds, silane coupling agents, and a first alcohol solvent. The molar ratio of the polyether compound to the silane coupling agent is 1.5-2.5:1, and the amount of the first alcohol solvent added is 8-25% of the total mass of the wetting modifier. The raw materials for the binding reinforcing agent include isocyanate compounds, hydroxyl-terminated polymers, and ester solvents. The molar ratio of the isocyanate compounds to the hydroxyl-terminated polymers is 1.5-2.5:1, and the amount of ester solvent added is 3-12% of the total mass of the binding reinforcing agent. The raw materials for the reaction inhibitor include lithium salt, dispersant, and second alcohol solvent. The mass ratio of lithium salt to dispersant is 4-6:1, and the amount of second alcohol solvent added is 60-85% of the total mass of the reaction inhibitor.

[0005] Optionally, the polar organic solvent includes one of N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF).

[0006] Optionally, the molecular weight of the polyether compound is 2000-8000.

[0007] Optionally, the silane coupling agent includes one of γ-glycidoxypropyltrimethoxysilane (KH-560), γ-aminopropyltriethoxysilane (KH-550), and vinyltriethoxysilane (A-151).

[0008] Optionally, the first alcohol solvent and the second alcohol solvent may each independently include ethanol, isopropanol, n-butanol, etc.

[0009] Optionally, the lithium salt is lithium salt nanoparticles with a particle size of 5-30 nm, and the lithium salt includes lithium oxide (Li3PO4), lithium fluoride (LiF), lithium sulfate (Li2SO4), etc.

[0010] Optionally, the isocyanate compound includes one of hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), and diphenylmethane diisocyanate (MDI).

[0011] Optionally, the molecular weight of the hydroxyl-terminated polymer is 2000-6000.

[0012] Optionally, the ester solvent includes one of ethyl acetate, butyl acetate, and ethyl propionate.

[0013] Optionally, the molecular weight of the dispersant is 8000-25000.

[0014] Optionally, the dispersant includes one of polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), and polyacrylic acid (PAA).

[0015] Optionally, the thickness of the positive electrode active layer is 50-140 μm.

[0016] Optionally, the thickness of the interface functional layer is 40-120 nm.

[0017] Optionally, the porosity of the positive electrode with high interfacial wetting and bonding properties is 20-40%.

[0018] This application also provides a method for preparing a positive electrode sheet with high interfacial wetting and binding properties, including: The positive electrode slurry is placed on both sides of the current collector and pre-dried; a modification liquid is placed on both sides of the pre-dried current collector, and the mixture is then cured and pressed to obtain the positive electrode sheet with high interfacial wetting and bonding performance.

[0019] Optionally, the positive electrode slurry can be prepared by a doctor blade coating method, wherein the coating thickness of the positive electrode slurry is 60-150 μm.

[0020] Optionally, the modified liquid can be applied by electrostatic spraying, with a spraying amount of 0.3-2.0 g / m³. 2 The voltage is 40-90 kV and the distance is 12-25 cm.

[0021] Optionally, the pre-drying temperature is 70-110℃ and the time is 8-20 min.

[0022] Optionally, the curing is low-temperature curing, and the conditions for low-temperature curing are: curing at a temperature of 110-160°C in an inert gas atmosphere for 15-40 minutes.

[0023] Optionally, the hot pressing temperature is 140-190℃, the pressure is 6-15 MPa, and the holding time is 4-12 min.

[0024] This application also provides a solid-state battery, including the positive electrode with high interface wetting and binding performance.

[0025] Compared with the prior art, the beneficial effects of this application include: This application provides a positive electrode sheet with high interfacial wetting and bonding performance. Specifically, on one hand, a positive electrode active layer and an interfacial functional layer are sequentially disposed on both sides of the current collector. The interfacial functional layer directly serves as the contact interface between the electrode and the electrolyte, avoiding the ion transport problems caused by traditional point contacts. This positive electrode sheet can improve the surface energy matching with sulfide and oxide solid electrolytes, increase the electrolyte wetting area ratio, improve the ionic conductivity of the electrode-electrolyte interface, and increase the discharge capacity at 0.1C rate. Furthermore, by setting an interfacial functional layer containing a specific modified liquid outside the positive electrode active layer, the physicochemical properties of the electrode-electrolyte interface are synergistically optimized, solving the problems of insufficient interfacial wettability and weak solid-solid bonding in traditional wet-process positive electrodes. Specifically, the design of the interfacial functional layer allows the modified liquid to directly serve as the contact interface between the electrode and the electrolyte. Through precise control of the components, multiple functions are achieved, including surface energy matching, enhanced chemical bonding, and suppression of side reactions, avoiding the ion transport dead zone problem caused by traditional point contacts. On the other hand, through the precise proportioning and synergistic effect of the components of the positive electrode slurry and modified liquid provided by the technical solution of this application, the resulting interfacial functional layer can effectively solve the problems of insufficient wettability of the electrode-electrolyte interface and weak bonding force of the solid-solid interface, while suppressing the occurrence of interfacial side reactions and improving the overall interfacial performance. Detailed Implementation

[0026] As used in this article: "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0027] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0028] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0029] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0030] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (where K is any number representing a multiplier). It is important to understand that, unlike parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0031] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0032] To better explain the technical solution provided in this application, the technical solution will be described in its entirety before proceeding with specific implementation methods.

[0033] In one aspect, this application provides a positive electrode sheet with high interfacial wetting and binding performance, including a current collector, a positive electrode active layer, and an interfacial functional layer.

[0034] The positive electrode active layer and the interface functional layer are sequentially disposed on the front and back sides of the current collector.

[0035] The raw materials for the positive electrode active layer include a positive electrode active slurry, which in turn includes a positive electrode active material, a conductive agent, a binder, and a polar organic solvent. The mass ratio of the positive electrode active material, the conductive agent, the binder, and the polar organic solvent is 80-90:2-5:3-7:8-15.

[0036] Optionally, the mass ratio of the positive electrode active material, the conductive agent, the binder, and the polar organic solvent can be 80:2:3:8, 85:3:5:10, 85:3:5:12, 90:5:7:15, or any ratio between 80-90:2-5:3-7:8-15.

[0037] The raw materials of the interface functional layer include a modified liquid, and the raw materials of the modified liquid include a wetting modifier, a binding enhancer, and a reaction inhibitor. The volume ratio of the wetting modifier, the binding enhancer, and the reaction inhibitor is 4-6:2-4:1-3.

[0038] Optionally, the volume ratio of the wetting modifier, binding enhancer, and reaction inhibitor can be 4:2:1, 5:3:2, 5:4:3, or any ratio between 4-6:2-4:1-3.

[0039] The raw materials of the impregnation modifier include polyether compounds, silane coupling agents, and a first alcohol solvent. The molar ratio of the polyether compound to the silane coupling agent is 1.5-2.5:1, and the amount of the first alcohol solvent added is 8-25% of the total mass of the impregnation modifier.

[0040] It is understandable that the ether bonds in polyether compounds can react with Li in solid electrolytes. + Coordination occurs, and the hydrolyzable groups in the silane coupling agent hydrolyze to form hydroxyl groups, which then undergo a condensation reaction with the hydroxyl groups on the electrode surface, constructing an "electrophilic" modified layer on the electrode surface, thereby increasing the electrode surface energy from 35-45 mJ / m 2 Increased to 60-90 mJ / m 2 It can match the surface energy of sulfide and oxide electrolytes to achieve full wetting of the electrode by the electrolyte (wetting area ratio ≥90%).

[0041] Optionally, the molar ratio of the polyether compound to the silane coupling agent in the wetting modifier can be 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, or any value between 1.5 and 2.5:1. The amount of the first alcohol solvent added can be 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25% of the total mass of the wetting modifier, or any value between 8% and 25%.

[0042] The raw materials for the binding reinforcing agent include isocyanate compounds, hydroxyl-terminated polymers, and ester solvents. The molar ratio of the isocyanate compounds and the hydroxyl-terminated polymers is 1.5-2.5:1, and the amount of ester solvent added is 3-12% of the total mass of the binding reinforcing agent.

[0043] It is understandable that the active functional groups contained in the isocyanate compounds in the reinforcing component can chemically react with the hydroxyl groups on the surface of the active material, the oxygen-containing functional groups on the surface of the conductive agent, and the active hydrogen in the binder to form covalent bonds. This transforms the traditional physical adsorption binding into a dual binding of "physical adsorption + covalent bond", increasing the interfacial peel strength from below 5 N / m to 12-30 N / m, effectively resisting volume expansion and interfacial separation during electrode cycling.

[0044] Optionally, the molar ratio of isocyanate compounds and hydroxyl-terminated polymers can be 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, or any value between 1.5 and 2.5:1. The amount of ester solvent added can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, or 12% of the total mass of the interface reinforcing agent, or any value between 3% and 12%.

[0045] The raw materials for the reaction inhibitor include lithium salt, dispersant, and second alcohol solvent. The mass ratio of lithium salt to dispersant is 4-6:1, and the amount of second alcohol solvent added is 60-85% of the total mass of the reaction inhibitor.

[0046] It is understandable that lithium salt nanoparticles can form a dense ionic conductive layer at the electrode-electrolyte interface. On the one hand, this prevents transition metal ions from diffusing into the electrolyte and inhibits the formation of insulating reaction products. On the other hand, the anions in the lithium salt can fix the active anions in the electrolyte, reduce the formation of the space charge layer, and keep the increase in interfacial impedance within 25%.

[0047] Optionally, the mass ratio of lithium salt to dispersant can be 4:1, 5:1, 6:1, or any value between 4 and 6:1.

[0048] In an optional embodiment, the polar organic solvent includes one of N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF).

[0049] In one optional embodiment, the polyether compound has a molecular weight of 2000-8000.

[0050] Optionally, the molecular weight of the polyether compound can be 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, or any value between 2000 and 8000.

[0051] In an optional embodiment, the silane coupling agent comprises one of γ-glycidoxypropyltrimethoxysilane (KH-560), γ-aminopropyltriethoxysilane (KH-550), and vinyltriethoxysilane (A-151).

[0052] In an optional embodiment, the first alcohol solvent and the second alcohol solvent each independently include ethanol, isopropanol, n-butanol, etc.

[0053] In one optional embodiment, the lithium salt is lithium salt nanoparticles with a particle size of 5-30 nm, and the lithium salt includes lithium phosphate (Li3PO4), lithium fluoride (LiF), lithium sulfate (Li2SO4), etc.

[0054] Optionally, the particle size of the lithium salt nanoparticles can be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, or any value between 5 and 50 nm.

[0055] In an optional embodiment, the isocyanate compound includes one of hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), and diphenylmethane diisocyanate (MDI).

[0056] In one optional embodiment, the molecular weight of the hydroxyl-terminated polymer is 2000-6000.

[0057] In an optional embodiment, the molecular weight of the hydroxyl-terminated polymer can be 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, or any value between 2000 and 6000.

[0058] In one optional embodiment, the ester solvent includes ethyl acetate, butyl acetate, ethyl propionate, etc.

[0059] In one optional embodiment, the dispersant has a molecular weight of 8000-25000.

[0060] Optionally, the molecular weight of the dispersant can be 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, or any value between 8000 and 25000.

[0061] In an optional embodiment, the dispersant comprises one of polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), and polyacrylic acid (PAA).

[0062] In one optional embodiment, the thickness of the positive electrode active layer is 50-140 μm.

[0063] In one optional implementation, the thickness of the interface functional layer is 40-120 nm.

[0064] In an optional embodiment, the porosity of the positive electrode with high interfacial wetting and bonding properties is 20-40%.

[0065] Optionally, the porosity of the positive electrode with high interfacial wetting and bonding performance can be 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 35%, 38%, 40%, or any value between 20% and 40%.

[0066] Secondly, this application also provides a method for preparing a positive electrode sheet with high interfacial wetting and bonding properties, including: The positive electrode slurry is placed on both sides of the current collector and pre-dried; a modification liquid is placed on both sides of the pre-dried current collector, and the mixture is then cured and pressed to obtain the positive electrode sheet with high interfacial wetting and bonding performance.

[0067] In one optional embodiment, the positive electrode slurry is prepared by blade coating, wherein the coating thickness of the positive electrode slurry is 60-150 μm.

[0068] Optionally, the coating thickness of the positive electrode slurry is 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm, or any value between 60 and 150μm.

[0069] In one optional embodiment, the modified liquid is prepared by electrostatic spraying, with a spraying amount of 0.3-2.0 g / m³. 2The voltage is 40-90 kV and the distance is 12-25 cm.

[0070] Specifically, electrostatic spraying uses a high-voltage electric field to atomize the modified liquid into nano-sized droplets (40-250 nm in diameter), which can penetrate the pore structure of the semi-dry electrode to achieve all-round modification of the "surface + internal pores"; low-temperature curing (110-160℃) avoids the destruction of the active material structure caused by high temperature, while ensuring that the modified liquid components react fully.

[0071] The atomized modified droplets can form a uniform functional coating (40-120 nm thick) on the inner wall of the electrode pores, which improves the wettability of the electrolyte in the pores and enhances the binding force between the active material and the conductive agent in the pores. During the low-temperature curing process, the reaction rate between the modified liquid components and the electrode material is controllable, avoiding the increase in interface rigidity caused by excessive reaction, and taking into account both the bonding strength and the electrode flexibility (the bending radius can reach 3-8 mm without cracking).

[0072] Optionally, the coating amount for electrostatic spraying can be 0.3 g / m². 2 0.4 g / m 2 0.5 g / m 2 0.6 g / m 2 0.7g / m 2 0.8 g / m 2 0.9 g / m 2 1 g / m 2 1.1 g / m 2 1.2 g / m 2 1.3 g / m 2 1.4 g / m 2 1.5 g / m 2 1.6g / m 2 1.7 g / m 2 1.8 g / m 2 1.9 g / m 2 2 g / m 2 2.1 g / m 2 2.2 g / m 2 2.3 g / m 2 2.4 g / m 2 2.5g / m 2 Or 0.3-2.5 g / m 2The voltage for electrostatic spraying can be any value between 40 kV, 45 kV, 50 kV, 55 kV, 60 kV, 65 kV, 70 kV, 75 kV, 80 kV, 85 kV, 90 kV, or any value between 40 and 90 kV; the spraying distance can be 12 cm, 13 cm, 14 cm, 15 cm, 16 cm, 17 cm, 18 cm, 19 cm, 20 cm, 21 cm, 22 cm, 23 cm, 24 cm, 25 cm, or any value between 12 and 25 cm.

[0073] In one optional embodiment, the pre-drying temperature is 70-110°C and the time is 8-20 minutes.

[0074] Optionally, the pre-drying temperature can be 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, or any value between 70℃ and 110℃; the pre-drying time can be 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, or any value between 8 min and 20 min.

[0075] In one optional embodiment, the curing is low-temperature curing, wherein the low-temperature curing conditions are: curing at a temperature of 110-160°C for 15-40 min in an inert gas atmosphere.

[0076] Optionally, the low-temperature curing temperature can be 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, or any value between 110℃ and 160℃; the low-temperature curing time can be 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, or any value between 15 min and 50 min.

[0077] In one optional embodiment, the hot pressing temperature is 140-190℃, the pressure is 6-15 MPa, and the holding time is 4-12 min.

[0078] Specifically, the hot-pressing temperature is 140-190℃ and the pressure is 6-15 MPa, which matches the curing temperature of the modified liquid. During the hot-pressing process, the flexible segments in the modified liquid undergo slight flow, filling the tiny gaps inside the electrode and promoting close contact between the electrolyte and the electrode.

[0079] Understandably, hot pressing increases the electrode-electrolyte interface contact pressure from 2-3 MPa in traditional processes to 6-15 MPa, further increasing the contact area. The flexible segments in the modified liquid can alleviate stress concentration during hot pressing, preventing electrode brittleness. At the same time, during cycling, the segment movement can absorb the stress generated by the electrode volume expansion, maintaining interface stability.

[0080] Optionally, the hot pressing temperature can be 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, or any value between 140℃ and 190℃; the pressure can be 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, 15 MPa, or any value between 6℃ and 15 MPa; the holding time can be 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, or any value between 4℃ and 12 min.

[0081] This application also provides a solid-state battery, including the positive electrode with high interface wetting and binding performance.

[0082] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0083] Example 1 This embodiment provides a positive electrode with high interface wetting and binding performance: The current collector is a 12μm thick aluminum foil current collector, the thickness of the positive electrode active layer is 95μm, and the thickness of the interface functional layer is 80nm.

[0084] The raw materials for the positive electrode active layer are positive electrode active slurry, which consists of: 85 g of NCM811 active material, 3 g of carbon nanotube / graphene composite conductive agent (mass ratio 2:1), 5 g of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP, hexafluoropropylene unit percentage 12%), and 12 g of N-methylpyrrolidone (NMP) (mass ratio 85:3:5:12).

[0085] The raw materials for the interface functional layer include a modified liquid, which consists of a wetting modifier, a binding enhancer, and a reaction inhibitor, in a volume ratio of 5:3:2.

[0086] The raw materials for the impregnation modifier are: 30 g of polyethylene glycol monomethyl ether (MPEG, molecular weight 4000) and 10 g of γ-glycidyl etheroxypropyltrimethoxysilane (KH-560), with a mass ratio of 3:1, and 8 g of ethanol (accounting for 20% of the total mass) are added.

[0087] The raw materials for the binding reinforcing agent are: 2 mol of hexamethylene diisocyanate (HDI), 1 mol of hydroxyl-terminated polybutadiene (HTPB, molecular weight 4000) (molar ratio 2:1), and 6 g of ethyl acetate (accounting for 10% of the total mass).

[0088] The raw materials for the reaction inhibitor are 5g of Li3PO4 nanoparticles (particle size 10 nm) and 1g of polyvinylpyrrolidone (PVP, molecular weight 15000) (mass ratio 5:1), dispersed in 12g of ethanol.

[0089] This embodiment provides a method for preparing a positive electrode sheet with high interfacial wetting and binding performance. The specific steps are as follows: Positive electrode slurry coating: The slurry is coated onto a 12μm thick aluminum foil current collector using a doctor blade coater. The coating thickness is set to 100μm. Then, it is placed in a forced-air drying oven and pre-dried at 90℃ for 12 min to remove about 35% of the solvent, forming a semi-dry electrode.

[0090] Modified liquid spraying: Electrostatic spraying equipment is used, with a spraying rate set to 1.0 g / m³. 2 With an electrostatic voltage of 60 kV and a spraying distance of 18 cm, the interface modification liquid was evenly sprayed onto the surface and internal pores of the semi-dry electrode.

[0091] Low-temperature curing: The coated electrode is transferred to an inert atmosphere furnace (argon atmosphere) and cured at 135°C for 25 minutes, then naturally cooled to room temperature to form an interface functional layer.

[0092] Hot pressing: The cured electrode was placed in a hot press, the temperature was set to 160℃ and the pressure to 10 MPa, and the pressure was maintained for 8 min. The electrode porosity was measured to be 30%.

[0093] This embodiment also provides a solid-state battery: With Li7P3S 11 A CR2032 solid-state battery was assembled in an argon glove box using a sulfide solid electrolyte (200 μm thick) and a lithium metal sheet (500 μm thick) as the negative electrode.

[0094] Example 2 This embodiment provides a positive electrode with high interface wetting and binding performance: The current collector is a 12μm thick aluminum foil current collector, the thickness of the positive electrode active layer is 85μm, and the thickness of the interface functional layer is 60nm.

[0095] The raw materials for the positive electrode active layer are positive electrode active slurry, which consists of: 88 g of lithium-rich manganese-based active material, 2 g of carbon nanotube / graphene composite conductive agent (mass ratio 2:1), 4 g of PVDF-HFP (hexafluoropropylene unit accounting for 10%), and 12 g of N-methylpyrrolidone (NMP) (mass ratio 88:2:4:10).

[0096] The raw materials for the interface functional layer include a modified liquid, which consists of a wetting modifier, a binding enhancer, and a reaction inhibitor, in a volume ratio of 5:3:2.

[0097] The raw materials for the impregnation modifier are: 30 g of polyethylene glycol monomethyl ether (MPEG, molecular weight 4000) and 10 g of γ-glycidyl etheroxypropyltrimethoxysilane (KH-560), with a mass ratio of 3:1, and 8 g of ethanol (accounting for 20% of the total mass) are added.

[0098] The raw materials for the binding reinforcing agent are: 2 mol of hexamethylene diisocyanate (HDI), 1 mol of hydroxyl-terminated polybutadiene (HTPB, molecular weight 4000) (molar ratio 2:1), and 6 g of ethyl acetate (accounting for 10% of the total mass).

[0099] The raw materials for the reaction inhibitor are 5g of Li3PO4 nanoparticles (particle size 10 nm) and 1g of polyvinylpyrrolidone (PVP, molecular weight 15000) (mass ratio 5:1), dispersed in 12g of ethanol.

[0100] This embodiment provides a method for preparing a positive electrode sheet with high interfacial wetting and binding performance. The specific steps are as follows: Positive electrode slurry coating: The slurry is coated onto a 12μm thick aluminum foil current collector using a doctor blade coater. The coating thickness is set to 90μm. Then, it is placed in a forced-air drying oven and pre-dried at 85℃ for 10 minutes to remove about 30% of the solvent, forming a semi-dry electrode.

[0101] Modified liquid spraying: Electrostatic spraying equipment is used, with a spraying rate set to 0.8 g / m³. 2 With an electrostatic voltage of 55 kV and a spraying distance of 16 cm, the interface modification liquid was evenly sprayed onto the surface and internal pores of the semi-dry electrode.

[0102] Low-temperature curing: The coated electrode is transferred to an inert atmosphere furnace (argon atmosphere) and cured at 125°C for 22 minutes, then naturally cooled to room temperature to form an interface functional layer.

[0103] Hot pressing: The cured electrode was placed in a hot press, the temperature was set to 150℃ and the pressure to 9 MPa, and the pressure was maintained for 7 min. The electrode porosity was measured to be 32%.

[0104] This embodiment also provides a solid-state battery: Li7La3Zr2O 12 (LLZO, particle size 500 nm) is an oxide solid electrolyte (thickness 250 μm) and a lithium-tin alloy (Li 90 Sn 10 A CR2032 solid-state battery was assembled using a 600 μm thick anode as the negative electrode.

[0105] Example 3 This embodiment provides a positive electrode with high interface wetting and binding performance: The current collector is a 12μm thick aluminum foil current collector, the thickness of the positive electrode active layer is 88μm, and the thickness of the interface functional layer is 70nm.

[0106] The raw materials for the positive electrode active layer are positive electrode active slurry, which are: 88 g of LiFePO4, 3 g of carbon nanotube / carbon black composite conductive agent (mass ratio 2:1), 4 g of PVDF-HFP (hexafluoropropylene unit accounts for 15%), and 11 g of N-methylpyrrolidone (NMP) (mass ratio 88:3:4:11).

[0107] The raw materials for the interface functional layer include a modified liquid, which consists of a wetting modifier, a binding enhancer, and a reaction inhibitor, in a volume ratio of 4.5:3:2.

[0108] The raw materials for the impregnation modifier are: 25 g of MPEG (molecular weight 3000) and 10 g of KH-560, with a mass ratio of 2.5:1, and 7 g of ethanol (accounting for 18% of the total mass) are added.

[0109] The raw materials for the binder are: 1.8 mol HDI, 1 mol HTPB (molecular weight 3500) (molar ratio 1.8:1), and 5 g of ethyl acetate (8% of the total mass).

[0110] The raw materials for the reaction inhibitor are 4.5g of Li3PO4 nanoparticles (particle size 15 nm) and 1g of PVP (molecular weight 12000) (mass ratio 4.5:1), dispersed in 10g of ethanol.

[0111] This embodiment provides a method for preparing a positive electrode sheet with high interfacial wetting and binding performance. The specific steps are as follows: Positive electrode slurry coating: The slurry is coated onto a 12μm thick aluminum foil current collector using a doctor blade coater. The coating thickness is set to 90μm. Then, it is placed in a forced-air drying oven and pre-dried at 85℃ for 12 minutes to remove about 30% of the solvent, forming a semi-dry electrode.

[0112] Modified liquid spraying: Electrostatic spraying equipment is used, with a spraying rate set to 0.8 g / m³. 2 With an electrostatic voltage of 55 kV and a spraying distance of 17 cm, the interface modification liquid was evenly sprayed onto the surface and internal pores of the semi-dry electrode.

[0113] Low-temperature curing: The coated electrode is transferred to an inert atmosphere furnace (argon atmosphere) and cured at 130°C for 25 minutes, then naturally cooled to room temperature to form an interface functional layer.

[0114] Hot pressing: The cured electrode was placed in a hot press, the temperature was set to 160℃ and the pressure to 10MPa, and the pressure was maintained for 7 min. The electrode porosity was measured to be 29%.

[0115] This embodiment also provides a solid-state battery: Using PEO-LiTFSI-LLZO composite solid electrolyte (300μm thick) and lithium-tin alloy (Li 90 Sn 10 A CR2032 solid-state battery was assembled using a 600μm thick anode as the negative electrode.

[0116] Comparative Example 1 This comparative example provides a process for preparing a positive electrode using a conventional process without interface modification: The raw materials for preparing the positive electrode active layer are positive electrode active slurry, which consists of: 85 g of NCM811 active material, 3 g of carbon black conductive agent, 5 g of pure PVDF binder, and 12 g of NMP (mass ratio 85:3:5:12).

[0117] Coating and drying: Coating thickness 100 μm, dry at 120℃ for 25 min, without modification liquid spraying and curing steps.

[0118] Hot pressing: 160℃, 10 MPa hot pressing for 8 min, porosity 30%. This comparative example also provides a solid-state battery: The prepared positive electrode sheet was then combined with Li7P3S. 11 Electrolyte and lithium metal are used to assemble batteries.

[0119] Comparative Example 2 This comparative example provides a method for preparing a positive electrode sheet, the specific steps of which are as follows: At a different time than in Example 1, only the wetting modifier component of Example 1 was prepared, without adding binding enhancer and reaction inhibitor, and was added to the slurry of Comparative Example 1 at a mass ratio of 1% (1 g), while the proportions of the remaining slurries remained unchanged.

[0120] This comparative example also provides a solid-state battery, whose raw materials and preparation method are the same as those in Example 1.

[0121] Comparative Example 3 This comparative example provides a method for preparing a positive electrode: Compared to Example 1, the only difference lies in the modification process: the interface modification liquid formulation is the same as in Example 1, but it is applied manually with a brush (instead of electrostatic spraying), with a brush application rate of 1.0 g / m³. 2 (It only covers the electrode surface and cannot penetrate the pores).

[0122] This comparative example also provides a solid-state battery, whose raw materials and preparation method are the same as those in Example 1.

[0123] The electrical properties of the solid-state batteries prepared in the examples and comparative examples are shown in Table 1: Table 1. Electrochemical performance, volume expansion rate, interfacial ionic conductivity, peel strength, and impedance of all-solid-state batteries.

[0124] As shown in Table 1, this invention, through a multi-component synergistic interface functional layer design of "wetting modifier + binding enhancer + reaction inhibitor," combined with an electrostatic spraying penetration process, simultaneously solves the three core pain points of solid-state battery wet-process cathodes: "poor interface wetting, weak solid-solid bonding, and violent interface reactions." This enables the cathode sheet to achieve comprehensive breakthroughs in capacity, cycle stability, interface transport efficiency, and structural stability. Furthermore, the process is compatible with existing wet coating production lines, demonstrating significant industrialization potential. Compared with traditional processes and single modification schemes, this invention exhibits clear technical advantages and demonstrates outstanding inventiveness and practicality.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0126] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A positive electrode sheet with high interfacial wetting and bonding performance, characterized in that, Includes current collector, positive electrode active layer, and interface functional layer; The positive electrode active layer and the interface functional layer are sequentially disposed on the front and back sides of the current collector; The raw materials for the positive electrode active layer include a positive electrode active slurry, and the raw materials for the positive electrode active slurry include a positive electrode active material, a conductive agent, a binder, and a polar organic solvent. The mass ratio of the positive electrode active material, the conductive agent, the binder, and the polar organic solvent is 80-90:2-5:3-7:8-15. The raw materials of the interface functional layer include a modified liquid, and the raw materials of the modified liquid include a wetting modifier, a binding enhancer, and a reaction inhibitor. The volume ratio of the wetting modifier, the binding enhancer, and the reaction inhibitor is 4-6:2-4:1-3. The raw materials of the wetting modifier include polyether compounds, silane coupling agents, and a first alcohol solvent. The molar ratio of the polyether compound to the silane coupling agent is 1.5-2.5:1, and the amount of the first alcohol solvent added is 8-25% of the total mass of the wetting modifier. The raw materials for the binding reinforcing agent include isocyanate compounds, hydroxyl-terminated polymers, and ester solvents. The molar ratio of the isocyanate compounds to the hydroxyl-terminated polymers is 1.5-2.5:1, and the amount of ester solvent added is 3-12% of the total mass of the binding reinforcing agent. The raw materials for the reaction inhibitor include lithium salt, dispersant, and second alcohol solvent. The mass ratio of lithium salt to dispersant is 4-6:1, and the amount of second alcohol solvent added is 60-85% of the total mass of the reaction inhibitor.

2. The positive electrode sheet with high interfacial wetting and bonding performance according to claim 1, characterized in that, At least one of the following conditions must be met: a. The polar organic solvent includes one of N-methylpyrrolidone, dimethyl sulfoxide, and N,N-dimethylformamide; b. The molecular weight of the polyether compound is 2000-8000; c. The silane coupling agent includes one of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and vinyltriethoxysilane; d. The first alcohol solvent and the second alcohol solvent each independently include one of ethanol, isopropanol, and n-butanol; e. The lithium salt is lithium salt nanoparticles, the particle size of the lithium salt nanoparticles is 5-30 nm, and the lithium salt includes at least one of lithium phosphate, lithium fluoride, and lithium sulfate; f. The isocyanate compound includes one of hexamethylene diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate; g. The molecular weight of the hydroxyl-terminated polymer is 2000-6000; h. The ester solvent includes one of ethyl acetate, butyl acetate, and ethyl propionate; i. The molecular weight of the dispersant is 8000-25000; j. The dispersant includes one of polyvinylpyrrolidone, polyethylene glycol, and polyacrylic acid.

3. The positive electrode sheet with high interfacial wetting and bonding performance according to claim 1, characterized in that, Meet any one of the following conditions: k. The thickness of the positive electrode active layer is 50-140 μm; l. The thickness of the interface functional layer is 40-120nm.

4. The positive electrode sheet with high interfacial wetting and bonding performance according to any one of claims 1-3, characterized in that, The porosity of the positive electrode with high interfacial wetting and bonding properties is 20-40%.

5. A method for preparing a positive electrode sheet with high interfacial wetting and bonding performance as described in any one of claims 1-4, characterized in that, include: The positive electrode active slurry is placed on both sides of the current collector and pre-dried; a modification liquid is placed on both sides of the pre-dried current collector, and the mixture is then cured and pressed to obtain the positive electrode sheet with high interfacial wetting and bonding performance.

6. The preparation method according to claim 5, characterized in that, At least one of the following conditions must be met: A. The positive electrode slurry is prepared by a doctor blade coating method, wherein the coating thickness of the positive electrode slurry is 60-150 μm; B. The modified liquid is prepared by electrostatic spraying, with a spraying amount of 0.3-2.0 g / m³. 2 The voltage is 40-90 kV and the distance is 12-25 cm.

7. The preparation method according to claim 5, characterized in that, The pre-drying temperature is 70-110℃, and the time is 8-20 minutes.

8. The preparation method according to claim 5, characterized in that, The curing is low-temperature curing, and the conditions for low-temperature curing are: curing at a temperature of 110-160°C in an inert gas atmosphere for 15-40 minutes.

9. The preparation method according to any one of claims 5-8, characterized in that, The hot pressing temperature is 140-190℃, the pressure is 6-15 MPa, and the holding time is 4-12 min.

10. A solid-state battery, characterized in that, The positive electrode sheet with high interfacial wetting and bonding properties as described in any one of claims 1-4.

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