Negative electrode interface self-repairing material, negative electrode plate, positive electrode interface material, positive electrode plate, solid electrolyte, solid-state battery and electric device

Abstract

The invention discloses a negative electrode interface self-repairing material, a negative electrode plate, a positive electrode interface material, a positive electrode plate, a solid electrolyte, a solid-state battery and an electric device, and relates to the technical field of batteries, the negative electrode interface self-repairing material comprises a porous material and a self-repairing material, the self-repairing material comprises a core layer material and a shell layer material at least partially coating the surface of the core layer material, the material of the core layer comprises a thiol-olefin repairing agent and a photoinitiator; the material of the shell layer comprises a self-repairing polymer. Silicon expansion can be inhibited through the porous electrolyte, meanwhile, an ion guide channel is constructed, interface impedance is reduced, meanwhile, the porous electrolyte is stable in chemical performance and compatible with a silicon-based material, and side reactions can be reduced. A three-dimensional network is formed through a mercaptan-olefin click chemical reaction of the self-repairing polymer, in-situ crosslinking can be triggered when cracks are generated, interface cracks can be rapidly and dynamically repaired, fracture of a conductive ion channel is reduced, and therefore interface impedance is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a negative electrode interface self-repairing material, a negative electrode sheet, a positive electrode interface material, a positive electrode sheet, a solid-state electrolyte, a solid-state battery and an electric device. BACKGROUND

[0002] In the field of new energy vehicles, high-energy-density solid-state batteries are considered as a core technology to break through the endurance bottleneck. Among them, the "NCM9 system high-nickel positive electrode + SiOx / C silicon-based negative electrode" system has attracted much attention due to the positive electrode theoretical specific capacity > 200 mAh / g and the negative electrode specific capacity > 1000 mAh / g, but its industrialization faces two major challenges: first, the interface impedance problem, the solid-solid contact between the solid-state electrolyte and the high-activity electrode is poor, which leads to a significant increase in interface impedance (positive electrode side > 100 Ω·cm², negative electrode side > 80 Ω·cm²), causing DCR to exceed the standard (> 3 mΩ), low energy efficiency and gas production risk. Second, the dynamic failure problem, the volume expansion of the silicon-based negative electrode in the cycle is > 25%, which leads to the rupture of the interface layer and aggravates the side reaction, and the capacity attenuation rate is > 20% / 100 cycle. SUMMARY

[0003] The present application provides a negative electrode interface self-repairing material, a negative electrode sheet, a positive electrode interface material, a positive electrode sheet, a solid-state electrolyte, a solid-state battery and an electric device to improve the impedance of silicon-based materials and reduce cracks and ruptures.

[0004] In a first aspect, the present application provides a negative electrode interface self-repairing material, comprising a porous material and a self-repairing material, wherein: The porous material comprises a porous electrolyte; The self-repairing material comprises a core layer material and a shell layer material at least partially coated on the surface of the core layer material; The core layer material comprises a thiol-olefin repair agent and a photoinitiator; The shell layer material comprises a self-repairing polymer.

[0005] The present application can inhibit the expansion of silicon through the porous electrolyte, while constructing ion-conducting channels, reducing interface impedance, and the porous electrolyte has stable chemical properties and is compatible with silicon-based materials, which can reduce the occurrence of side reactions. Through the Thiol-Ene Click Reaction between the olefin monomer (such as trimethylolpropane triacrylate / pentaerythritol tetraacrylate) and the thiol monomer (such as pentaerythritol tetra(3-mercaptopropionate)) under the catalysis of a photoinitiator, a three-dimensional network is formed, which can trigger in-situ crosslinking to realize rapid dynamic repair of interface cracks when cracks occur, reduce the breakage of ion-conducting channels, and thus reduce interface impedance. The Click Reaction is a high-efficiency coupling reaction between the thiol group (-SH) and the olefin group (C=C) catalyzed by a photoinitiator to form a stable sulfide bond (-S-C-), thereby dynamically repairing material damage. When cracks occur, new thiol / olefin groups are exposed at the fracture, and the photoinitiator catalyzes the re-bonding of the two under light, restoring the continuity of the ion-conducting channels.

[0006] In some embodiments, the porous electrolyte includes at least one of a sulfide electrolyte and a polymer electrolyte, the sulfide electrolyte and the polymer electrolyte have high stability, are compatible with silicon-based materials, have few side reactions, and can inhibit the expansion of silicon-based materials; and / or, The porosity of the porous electrolyte is 20% to 40%, and the porosity of the porous electrolyte in this range can provide sufficient ion-conducting channels and reduce interface impedance; and / or, The ionic conductivity of the porous electrolyte at 25°C is greater than or equal to 0.1 m S / cm. The ionic conductivity of the porous electrolyte at 25°C in this range can reduce interface impedance.

[0007] In some embodiments, the Thiol-Ene repair agent includes at least one of a reaction product of a thiol-based compound and an olefin-based monomer, the reaction product of the thiol-based compound and the olefin-based monomer has the advantages of fast photocuring, high crosslinking density, and dynamic reversibility, wherein the thiol-based compound includes but is not limited to pentaerythritol tetra(3-mercaptopropionate), trimethylolpropane tri(3-mercaptopropionate), and tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate. The olefin-based monomer includes but is not limited to trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and 1,6-hexanediol diacrylate; and / or, The photo initiator includes at least one of TPO (diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide), Irgacure 819 (bis (2,4,6-trimethylbenzoyl) phenyl phosphine oxide), Irgacure 184 (1-hydroxycyclohexyl phenyl ketone), Darocur 1173 (2-hydroxy-2-methyl-1-phenyl-1-propanone), and at least one of the above initiators can be selected to match the spectrum of the thiol-olefin system; and / or, The self-repairing polymer includes at least one of polyurethane acrylate, polythioether, disulfide bond-containing cross-linked polyurethane, and acylhydrazone bond cross-linked polyurethane, and the above self-repairing polymer has a glass transition temperature less than -20℃, can adapt to the stress fluctuation of the silicon-based material expansion, and has a repair trigger condition of UV light or local stress greater than 8 MPa, which matches the working condition of the battery and has a repair efficiency as high as 90%; and / or, The diameter of the core layer is 150-250 nm, and the diameter of the core layer in this range can enable the self-repairing polymer to be embedded in the pores (pore diameter of the porous layer is 10-50 nm) and effectively release the repair agent; and / or, The thickness of the shell layer is 40-60 nm, and the thickness of the shell layer in this range can balance the mechanical strength and the rupture sensitivity; and / or, The mass ratio of the thiol-olefin repair agent to the photo initiator is (90-99): 1, and the mass ratio of the thiol-olefin repair agent to the photo initiator in this range can reduce the side reaction caused by excess initiator and improve the repair efficiency; and / or, The mass ratio of the porous material to the self-repairing material is (10-19): 1, and the mass ratio of the porous material to the self-repairing material in this range can improve the pore filling rate while maintaining the ionic conductivity.

[0008] In a second aspect, the application provides a negative electrode sheet, including a current collector, a silicon-based negative electrode active material layer arranged on at least one side of the current collector, and a self-repairing layer arranged on the side of the silicon-based negative electrode active material layer away from the current collector, wherein the material of the self-repairing layer includes the negative electrode interface self-repairing material as described in the first aspect.

[0009] The silicon expansion can be inhibited by the porous electrolyte, while the ion-conducting channel is constructed, the interface impedance is reduced, and the chemical stability of the porous electrolyte is stable and compatible with the silicon-based material, so that the occurrence of side reactions can be reduced. The thiol-olefin click chemistry reaction (Thiol-Ene Click Reaction) is triggered by the self-repairing polymer formed by the thiol-olefin click chemistry reaction between the olefin monomer (such as trimethylolpropane triacrylate / quaternary acrylate in example 1 / 2) and the thiol monomer (such as quaternary acrylate in example 3) under the catalysis of a photoinitiator, which forms a three-dimensional network. When a crack occurs, in-situ crosslinking is triggered to realize rapid dynamic repair of the interface crack, reduce the breakage of the ion-conducting channel, and thus reduce the interface impedance.

[0010] In some embodiments, the thickness ratio of the silicon-based negative electrode active material layer to the self-repairing layer is (9-11): 1. When the thickness ratio of the silicon-based negative electrode active material layer to the self-repairing layer is within this range, the crack repair can be provided while reducing the occupation of the silicon-based negative electrode active material, reducing the impact on the energy density of the battery; and / or, The thickness of the self-repairing layer is 1-5 μm. When the thickness of the self-repairing layer is within this range, the ion-conducting channel can be provided, the crack can be repaired, the occupation of the silicon-based negative electrode active material can be reduced, and the impact on the energy density of the battery can be reduced.

[0011] In a third aspect, the present application provides a positive electrode interface material, comprising a solid-state electrolyte, a flexible matrix, a composite lithium salt, and a cellulose reinforcing agent, wherein: The composite lithium salt comprises a first lithium salt and a second lithium salt, the first lithium salt has dissociability, and the second lithium salt has film-forming property; The solid-state electrolyte is in a nano-seed state.

[0012] The solid-state electrolyte in a nano-seed state can construct an ion-conducting channel, and has good chemical stability, is compatible with the positive electrode material, has few side reactions, and has a small nano-seed state particle size, facilitating gradient arrangement. The first lithium salt with dissociability can increase the number of lithium ion migrations, which is conducive to increasing the lithium ion concentration. The second lithium salt with film-forming property as a film-forming additive can help form a stable CEI layer at the positive electrode interface, inhibit the oxygen release side reaction of the positive electrode, reduce the oxygen vacancies formed by the loss of oxygen, and reduce gas production. The flexible matrix can improve the interface fitting capability, and the cellulose reinforcing agent can improve the tensile strength and elastic modulus of the interface layer.

[0013] In some embodiments, the solid-state electrolyte comprises at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide, and an oxide-polymer composite electrolyte. Selecting at least one of the above solid-state electrolytes has good chemical stability, high ionic conductivity, and can construct an ion-conducting channel; and / or, The particle size of the solid-state electrolyte is 10-200 nm, the particle size of the solid-state electrolyte in this range can match the electrostatic spray deposition process (nozzle diameter 0.3 mm); and / or, The ionic conductivity of the solid-state electrolyte at 25°C is ≥0.1 m S / cm, the ionic conductivity of the solid-state electrolyte at 25°C in this range can improve the ability to conduct ions and increase the lithium ion concentration; and / or, The flexible matrix includes at least one of polyethylene oxide, polypropylene oxide, and polypropylene oxide, the above-mentioned flexible matrix is selected to have a glass transition temperature less than -40°C, which improves low-temperature flexibility and can improve interface adhesion, and the ion transference number of the flexible matrix is relatively high, which reduces interface resistance; and / or, The molecular weight of the flexible matrix is greater than or equal to 400 kDa, the molecular weight of the flexible matrix in this range can improve the mechanical strength of the interface layer and reduce cracks; and / or, The lithium ion transference number of the flexible matrix is greater than or equal to 0.4, the lithium ion transference number of the flexible matrix in this range can construct a lithium ion channel, reduce lithium ion aggregation at the interface, and reduce interface resistance; and / or, The cellulose reinforcing agent includes at least one of plant-derived nanocellulose (CNC) and bacterial-derived nanocellulose (BNC), the above-mentioned cellulose reinforcing agent is selected to improve the tensile strength and elastic modulus of the interface layer and reduce the probability of interface fracture failure; and / or, The fiber length of the cellulose reinforcing agent is 0.05-1 μm, the fiber length of the cellulose reinforcing agent in this range can form a three-dimensional network to enhance the tensile strength; and / or, The fiber diameter of the cellulose reinforcing agent is 40-70 nm. The fiber diameter of the cellulose reinforcing agent in this range can reduce agglomeration and improve dispersion uniformity.

[0014] In some embodiments, the first lithium salt includes at least one of a bis-sulfimide lithium salt and a borate lithium salt, the above-mentioned first lithium salt is selected to improve the lithium ion transference number and facilitate the increase of the lithium ion concentration, wherein the bis-sulfimide lithium salt includes but is not limited to lithium bis-trifluoromethanesulfonimide (LiTFSI) and lithium bis-fluorosulfonimide (LiFSI), and the borate lithium salt includes but is not limited to lithium bis-oxalato borate (LiBOB) and lithium difluoro-oxalato borate (LiDFOB); and / or, The second lithium salt includes at least one of a fluorine-containing lithium phosphate salt, an oxalate lithium salt, and a boron-containing lithium salt. The second lithium salt is selected as a film-forming additive, which helps to form a stable CEI layer at the positive electrode interface, inhibits the oxygen release side reaction of the positive electrode, reduces oxygen vacancies formed by lattice oxygen loss, and reduces gas production. The fluorine-containing lithium phosphate salt includes, but is not limited to, lithium difluorophosphate (LiPO2F2). The oxalate lithium salt includes, but is not limited to, lithium fluorooxalate borate (LiODFB). The borate lithium salt includes, but is not limited to, lithium tetrafluoroborate (LiBF4); and / or, The mass ratio of the first lithium salt to the second lithium salt is (3-5):1. The mass ratio of the first lithium salt to the second lithium salt in this range can balance the number of lithium ion migration and film-forming performance; and / or, The mass ratio of the solid-state electrolyte, the flexible matrix, the composite lithium salt, and the cellulose reinforcing agent is (65-75):(20-30):(0.5-1):(4-4.5). The mass ratio of the solid-state electrolyte, the flexible matrix, the composite lithium salt, and the cellulose reinforcing agent in this range can improve the stability of the gradient structure and the mechanical strength.

[0015] In a fourth aspect, the present application provides a positive electrode sheet, which includes a current collector, a positive electrode active material layer arranged on at least one side of the current collector, and a positive electrode interface layer arranged on a side of the positive electrode active material layer away from the current collector. The material of the positive electrode interface layer includes the positive electrode interface material according to the second aspect.

[0016] The solid-state electrolyte in the form of nanocrystalline seeds can construct ion-conducting channels, has good chemical stability, is compatible with the positive electrode material, has few side reactions, and has a small particle size in the form of nanocrystalline seeds, facilitating gradient arrangement. The first lithium salt with dissociability can improve the number of lithium ion migration, which is conducive to improving the lithium ion concentration. The second lithium salt with film-forming performance as a film-forming additive helps to form a stable CEI layer at the positive electrode interface, inhibits the oxygen release side reaction of the positive electrode, reduces oxygen vacancies formed by lattice oxygen loss, and reduces gas production. The flexible matrix can improve the interface adhesion, and the cellulose reinforcing agent can improve the tensile strength and elastic modulus of the interface layer.

[0017] In some embodiments, the thickness ratio of the positive electrode active material layer to the positive electrode interface layer is (8-10):1. The thickness ratio of the positive electrode active material layer to the positive electrode interface layer in this range can improve the ion-conducting performance of the positive electrode interface, reduce impedance, reduce the occupation of the positive electrode active material, and reduce the impact on the energy density of the battery; and / or, The thickness of the positive electrode interface layer is 3-10 μm. The thickness of the positive electrode interface layer in this range can improve the ion-conducting performance of the positive electrode interface, reduce impedance, reduce the occupation of the positive electrode active material, and reduce the impact on the energy density of the battery.

[0018] In some embodiments, in the positive electrode interface layer, the mass fraction of the solid-state electrolyte is arranged in a decreasing manner from the direction close to the positive electrode active material layer to the direction away from the positive electrode active material layer. The mass fraction of the solid-state electrolyte arranged in a decreasing manner can form a continuous ion channel, improve the ion conducting ability, which can be realized by an electric field dominant deposition gradient in electrostatic spraying. The voltage at the nozzle is +20 kV (positive electrode side), and the voltage of the substrate is -5 kV (electrolyte side), forming a potential gradient. The positively charged solid-state electrolyte particles are driven by the electric field force to deposit at a higher density (70%±5%) on the positive electrode side and decrease to (50%±5%) on the electrolyte side. The gradient is formed by the uneven spatial distribution of the electric field. At the same time, the temperature difference of the hot press plate is set, the positive electrode side (70-80°C), and the electrolyte side (40-60°C). The viscosity of the flexible matrix decreases at the high temperature side, and the molecular chain movement intensifies. Therefore, the flow of the flexible matrix further drives the migration of the solid-state electrolyte particles to the low temperature side, strengthening the gradient distribution.

[0019] In a fifth aspect, the present application provides a solid-state electrolyte, comprising a nano solid-state electrolyte, a flexible matrix, a lithium salt, and a cellulose reinforcing agent. The addition of the flexible matrix and the cellulose reinforcing agent in the solid-state electrolyte can inhibit electrolyte cracking, reduce cracks, reduce ion channel breakage, and reduce interface impedance. The lithium salt can construct lithium ion migration channels and improve ion transmission capacity, wherein: The solid-state electrolyte comprises at least one of lithium titanium aluminum phosphate, lithium germanium aluminum phosphate, lithium lanthanum zirconium oxide, and oxide-polymer composite electrolyte. Any of the above solid-state electrolytes can improve the stability of the solid-state electrolyte and reduce the probability of side reactions; and / or, The flexible matrix comprises at least one of polyethylene oxide, polypropylene oxide, and polypropylene oxide. At least one of the above flexible matrices can provide lithium ion migration channels; and / or, The lithium salt comprises at least one of bis-sulfonimide lithium salt and borate lithium salt. At least one of the above lithium salts can maintain high ion conductivity in the bulk phase; and / or, The cellulose reinforcing agent comprises at least one of plant-derived nanocellulose (CNC) and bacterial-derived nanocellulose (BNC). Selecting at least one of the above cellulose reinforcing agents can inhibit electrolyte cracking.

[0020] In some embodiments, the mass ratio of the nano solid-state electrolyte, the flexible matrix, the lithium salt, and the cellulose reinforcing agent is (55-65):(20-30):(5-15):(4-5). The mass ratio of the nano solid-state electrolyte, the flexible matrix, the lithium salt, and the cellulose reinforcing agent in this range can balance the conductivity, flexibility, and mechanical strength.

[0021] In a sixth aspect, the present application provides a solid-state battery, comprising a negative electrode sheet, a separator and a positive electrode sheet arranged in sequence, wherein the negative electrode sheet comprises the negative electrode sheet of the second aspect, the positive electrode sheet comprises the positive electrode sheet of the fourth aspect, and the solid-state battery comprises the solid-state battery of the fifth aspect.

[0022] The porous self-repairing layer on the negative electrode side can inhibit the expansion of the silicon-based material, while repairing the cracks generated, repairing the broken ion channels, reducing the interface resistance, and the second lithium salt is not contained in the solid-state electrolyte, which can reduce the decomposition of the second lithium salt in the bulk phase and improve the stability of the electrolyte. The second lithium salt of the positive electrode interface layer preferentially forms a dense CEI layer on the positive electrode surface, inhibits the positive electrode interface side reaction, reduces the gas production, while the first lithium salt increases the lithium ion transference number and reduces the interface impedance. When the positive electrode interface solid-state electrolyte nanoseeds are arranged in a gradient, the solid-state electrolyte nanoparticles of the composite electrolyte main body are uniformly distributed to form a conductive path, thereby reducing the overall impedance. Thus, the positive electrode, the negative electrode and the separator together synergistically reduce the battery impedance.

[0023] In a seventh aspect, the present application provides an electric device comprising the solid-state battery of the sixth aspect. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application are described clearly and completely. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0025] In the field of new energy vehicles, high-energy-density solid-state batteries are considered as a core technology to break through the endurance bottleneck. Among them, the "NCM9 series high-nickel positive electrode + SiOx / C silicon-based negative electrode" system is of great concern due to the positive electrode theoretical specific capacity > 200 mAh / g and the negative electrode specific capacity > 1000 mAh / g, but it faces two key challenges in industrialization: first, the interface impedance problem, the poor solid-solid contact between the solid-state electrolyte and the high-activity electrode, resulting in a significant increase in interface impedance (positive electrode side > 100 Ω·cm², negative electrode side > 80 Ω·cm²), leading to DCR exceeding the standard (> 3 mΩ), low energy efficiency and gas production risk. Second, the dynamic failure problem, the volume expansion of the silicon-based negative electrode during cycling is > 25%, which causes the interface layer to break and intensifies the side reaction, with a capacity decay rate > 20% / 100 cycles.

[0026] Conventional oxide (e.g., LLZO lithium lanthanum zirconium oxide) and polymer (e.g., PEO polyethylene oxide) composite electrolyte is in-situ solidified by liquid electrolyte (<10wt%) to reduce interface impedance. There is a phase separation problem: LLZO lithium lanthanum zirconium oxide and PEO polyethylene oxide form a discontinuous interface due to the difference in polarity, and the ion transport path is broken (impedance > 120 Ω·cm²). And the mechanical compatibility is insufficient, the elastic modulus of the polymer matrix is <1 GPa, which cannot inhibit the crack propagation caused by silicon expansion.

[0027] Conventional carbon layer or lithium thiophosphate sulfide layer is coated on the surface of SiOx to improve the interface stability, there is a static protection failure problem, the interface compatibility of the coating layer and the electrolyte is poor (impedance > 80 Ω·cm²), and the micro-cracks generated in the cycle cannot be dynamically repaired. And the electrochemical window is limited, the sulfide electrolyte is easy to react with the high-nickel positive electrode, resulting in gas production > 2 mL / Ah.

[0028] Therefore, the application provides a negative electrode interface self-repairing material, a negative electrode sheet, a positive electrode interface material, a positive electrode sheet, a solid-state electrolyte, a solid-state battery and an electric device to improve the impedance of silicon-based materials and reduce cracks and breakage.

[0029] In a first aspect, the application provides a negative electrode interface self-repairing material, comprising a porous material and a self-repairing material, wherein: The porous material comprises a porous electrolyte; The self-repairing material comprises a core layer material and a shell layer material at least partially coated on the surface of the core layer material; The core layer material comprises a thiol-olefin repair agent and a photoinitiator; The shell layer material comprises a self-repairing polymer.

[0030] The application can inhibit silicon expansion through the porous electrolyte, reduce interface impedance by constructing ion-conducting channels, and reduce the occurrence of side reactions by the stable chemical properties of the porous electrolyte and the compatibility with silicon-based materials. The thiol-olefin click chemistry reaction (Thiol-Ene Click Reaction) of the self-repairing polymer occurs through the catalysis of the photoinitiator under the catalysis of the olefin monomer (e.g., trimethylolpropane triacrylate / pentaerythritol tetraacrylate) and the thiol monomer (e.g., pentaerythritol tetra(3-mercaptopropionate)) to form a three-dimensional network, which can trigger in-situ crosslinking to realize rapid dynamic repair of interface cracks when cracks occur, reduce the breakage of ion-conducting channels, and thus reduce interface impedance. The click chemistry reaction is a high-efficiency coupling reaction between the thiol group (-SH) and the olefin group (C=C) catalyzed by the photoinitiator to form a stable sulfide bond (-S-C-), thereby dynamically repairing material damage. When cracks occur, new thiol / olefin groups are exposed at the fracture, and the photoinitiator catalyzes the re-bonding of the two under light to restore the continuity of the ion channel.

[0031] In some embodiments of the first aspect, the porous electrolyte includes at least one of a sulfide electrolyte and a polymer electrolyte. The sulfide electrolyte and the polymer electrolyte have high stability, match the silicon-based material, have few side reactions, and can inhibit the expansion of the silicon-based material. The sulfide electrolyte includes, but is not limited to, lithium phosphorus sulfide (Li3PS4) and lithium phosphorus sulfide (Li7P3S11). The polymer electrolyte includes, but is not limited to, polyethylene oxide (PEO).

[0032] In some embodiments of the first aspect, the porosity of the porous electrolyte is 20% to 40%. The porosity of the porous electrolyte in this range can provide sufficient ion conduction channels and reduce interface impedance.

[0033] In some embodiments of the first aspect, the ionic conductivity of the porous electrolyte at 25°C is greater than or equal to 0.1 m S / cm. The ionic conductivity of the porous electrolyte at 25°C in this range can reduce interface impedance.

[0034] In some embodiments of the first aspect, the thiol-olefin repair agent includes at least one of a reaction product of a thiol-based compound and an olefin-based monomer. The reaction product of the thiol-based compound and the olefin-based monomer has the advantages of fast photocuring, high cross-linking density, and dynamic reversibility. The thiol-based compound includes, but is not limited to, pentaerythritol tetra (3-mercaptopropionate), trimethylolpropane tri (3-mercaptopropionate), and tris [(3-mercaptopropionyloxy)-ethyl]-isocyanurate. The olefin-based monomer includes, but is not limited to, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and 1,6-hexanediol diacrylate.

[0035] In some embodiments of the first aspect, the photoinitiator includes at least one of TPO (diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide), Irgacure 819 (bis (2,4,6-trimethylbenzoyl) phenyl phosphine oxide), Irgacure 184 (1-hydroxycyclohexyl phenyl ketone), and Darocur 1173 (2-hydroxy-2-methyl-1-phenyl-1-propanone). Selecting at least one of the above initiators can match the spectrum of the thiol-olefin system.

[0036] In some embodiments of the first aspect, the self-healing polymer comprises at least one of polyurethane acrylate, polythioether, disulfide bond-containing cross-linked polyurethane, and acylhydrazone bond cross-linked polyurethane, and the glass transition temperature of the self-healing polymer is less than -20°C, which can adapt to the stress fluctuation of the silicon-based material expansion, and the repair trigger condition is UV light or local stress greater than 8 MPa, which matches the working condition of the battery, and the repair efficiency is as high as 90%.

[0037] In some embodiments of the first aspect, the diameter of the core layer is 150-250 nm, which can ensure that the microcapsules are embedded in the pores (pore diameter of the porous layer is 10-50 nm) and effectively release the repair agent.

[0038] In some embodiments of the first aspect, the thickness of the shell layer is 40-60 nm, which can balance the mechanical strength and the crack sensitivity.

[0039] In some embodiments of the first aspect, the mass ratio of the thiol-olefin repair agent to the photoinitiator is (90-99): 1, which can reduce the side reactions caused by excess initiator and improve the repair efficiency.

[0040] In some embodiments of the first aspect, the mass ratio of the porous material to the self-healing material is (10-19): 1, which can improve the pore filling rate while maintaining the ionic conductivity.

[0041] In the second aspect, the application provides a negative electrode sheet, which comprises a current collector, a silicon-based negative electrode active material layer arranged on at least one side of the current collector, and a self-healing layer arranged on the side of the silicon-based negative electrode active material layer away from the current collector, wherein the material of the self-healing layer comprises the negative electrode interface self-healing material as described in the first aspect.

[0042] The porous electrolyte can inhibit the expansion of silicon, construct ion-conducting channels, reduce the interface impedance, and is chemically stable and compatible with the silicon-based material, so that the occurrence of side reactions can be reduced. The thiol-olefin click chemistry reaction (Thiol-Ene Click Reaction) of the self-healing polymer formed by the olefin monomer (such as trimethylolpropane triacrylate / quaternary ammonium tetraacrylate in embodiments 1 / 2) and the thiol monomer (such as quaternary ammonium tetra (3-mercapto propionate) in embodiment 3) under the catalysis of the photoinitiator forms a three-dimensional network, which can trigger in-situ cross-linking to realize rapid dynamic repair of the interface cracks when the cracks occur, reduce the breakage of the ion-conducting channels, and thus reduce the interface impedance.

[0043] With reference to the second aspect, in some embodiments provided in the present application, a thickness ratio of the silicon-based negative electrode active material layer to the self-repairing layer is (9-11):1. When the thickness ratio of the silicon-based negative electrode active material layer to the self-repairing layer is within the range, the crack can be repaired, the ion conduction channel can be provided, the occupation of the silicon-based negative electrode active material can be reduced, and the influence on the energy density of the battery can be reduced.

[0044] With reference to the second aspect, in some embodiments provided in the present application, a thickness of the self-repairing layer is 1-5 μm. When the thickness of the self-repairing layer is within the range, the ion conduction channel can be provided, the crack can be repaired, the occupation of the silicon-based negative electrode active material can be reduced, and the influence on the energy density of the battery can be reduced.

[0045] In a third aspect, the present application provides a positive electrode interface material, comprising a solid-state electrolyte, a flexible matrix, a composite lithium salt and a cellulose reinforcing agent, wherein: The composite lithium salt comprises a first lithium salt and a second lithium salt, the first lithium salt has dissociability, and the second lithium salt has film-forming property. The solid-state electrolyte is in a nano-seed state.

[0046] The solid-state electrolyte in a nano-seed state can construct an ion conduction channel, has good chemical stability, is compatible with the positive electrode material, has few side reactions, and has a small nano-seed state particle size, facilitating gradient arrangement. The first lithium salt with dissociability can increase the number of lithium ion migrations, which is conducive to increasing the lithium ion concentration. The second lithium salt with film-forming property as a film-forming additive helps to form a stable CEI layer at the positive electrode interface, inhibits the oxygen release side reaction of the positive electrode, reduces oxygen vacancies formed by lattice oxygen loss, and reduces gas production. The flexible matrix can improve the interface adhesion, and the cellulose reinforcing agent can improve the tensile strength and elastic modulus of the interface layer.

[0047] With reference to the third aspect, in some embodiments provided in the present application, the solid-state electrolyte comprises at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide and an oxide-polymer composite electrolyte. The at least one of the above solid-state electrolytes has good chemical stability and high ionic conductivity, and can construct an ion conduction channel.

[0048] With reference to the third aspect, in some embodiments provided in the present application, a particle size of the solid-state electrolyte is 10-200 nm. When the particle size of the solid-state electrolyte is within the range, the solid-state electrolyte can match the electrostatic spray deposition process (nozzle diameter 0.3 mm).

[0049] In some embodiments of the third aspect, the solid-state electrolyte has an ionic conductivity of ≥ 0.1 mS / cm at 25°C. The ionic conductivity of the solid-state electrolyte in this range can improve the ability of ion conduction and increase the concentration of lithium ions.

[0050] In some embodiments of the third aspect, the flexible matrix comprises at least one of polyethylene oxide, polypropylene oxide, and polypropylene oxide. The flexible matrix has a glass transition temperature of less than -40°C, which improves the flexibility at low temperatures and the interface adhesion, and has a high ion transference number, which reduces the interface resistance.

[0051] In some embodiments of the third aspect, the flexible matrix has a molecular weight of ≥ 400 kDa. The flexible matrix with the molecular weight in this range can improve the mechanical strength of the interface layer and reduce cracks.

[0052] In some embodiments of the third aspect, the flexible matrix has a lithium ion transference number of ≥ 0.4. The flexible matrix with the lithium ion transference number in this range can form lithium ion channels, reduce the aggregation of lithium ions at the interface, and reduce the interface resistance.

[0053] In some embodiments of the third aspect, the cellulose reinforcing agent comprises at least one of plant-derived nanocellulose (CNC) and bacterial-derived nanocellulose (BNC). The cellulose reinforcing agent can improve the tensile strength and elastic modulus of the interface layer and reduce the probability of interface fracture failure.

[0054] In some embodiments of the third aspect, the cellulose reinforcing agent has a fiber length of 0.05-1 μm. The cellulose reinforcing agent with the fiber length in this range can form a three-dimensional network to improve the tensile strength.

[0055] In some embodiments of the third aspect, the cellulose reinforcing agent has a fiber diameter of 40-70 nm. The cellulose reinforcing agent with the fiber diameter in this range can reduce agglomeration and improve dispersion uniformity.

[0056] In some embodiments of the third aspect, the first lithium salt comprises at least one of a bis-sulfimide lithium salt and a borate lithium salt. The first lithium salt can improve the lithium ion transference number and increase the concentration of lithium ions. The bis-sulfimide lithium salt includes, but is not limited to, lithium bis-trifluoromethanesulfonimide (LiTFSI) and lithium bis-fluorosulfonimide (LiFSI). The borate lithium salt includes, but is not limited to, lithium bis(oxalato)borate (LiBOB) and lithium difluoro(oxalato)borate (LiDFOB).

[0057] In some embodiments provided by the third aspect, the second lithium salt comprises at least one of a fluorine-containing lithium phosphate salt, a lithium oxalate salt, and a lithium borate salt. The second lithium salt can be used as a film-forming additive to help form a stable CEI layer on the positive electrode interface, inhibit the oxygen release side reaction of the positive electrode, reduce oxygen vacancies formed by lattice oxygen loss, and reduce gas production. The fluorine-containing lithium phosphate salt includes, but is not limited to, lithium difluorophosphate (LiPO2F2). The lithium oxalate salt includes, but is not limited to, lithium fluorooxalate borate (LiODFB). The lithium borate salt includes, but is not limited to, lithium tetrafluoroborate (LiBF4).

[0058] In some embodiments provided by the third aspect, the mass ratio of the first lithium salt to the second lithium salt is (3-5): 1. The mass ratio of the first lithium salt to the second lithium salt in this range can balance the number of lithium ion migration and the film-forming performance.

[0059] In some embodiments provided by the third aspect, the mass ratio of the solid-state electrolyte, the flexible matrix, the composite lithium salt, and the cellulose reinforcing agent is (65-75):(20-30):(0.5-1):(4-4.5). The mass ratio of the solid-state electrolyte, the flexible matrix, the composite lithium salt, and the cellulose reinforcing agent in this range can improve the stability of the gradient structure and the mechanical strength.

[0060] In a fourth aspect, the present application provides a positive electrode sheet, which comprises a current collector, a positive electrode active material layer arranged on at least one side of the current collector, and a positive electrode interface layer arranged on a side of the positive electrode active material layer away from the current collector. The material of the positive electrode interface layer comprises the positive electrode interface material according to the second aspect.

[0061] The solid-state electrolyte in the form of nanocrystalline seeds can construct ion-conducting channels, has good chemical stability, is compatible with the positive electrode material, has few side reactions, and has a small particle size, which is convenient for gradient arrangement. The first lithium salt with dissociability can improve the number of lithium ion migration and is conducive to improving the lithium ion concentration. The second lithium salt with film-forming performance as a film-forming additive can help form a stable CEI layer on the positive electrode interface, inhibit the oxygen release side reaction of the positive electrode, reduce oxygen vacancies formed by lattice oxygen loss, and reduce gas production. The flexible matrix can improve the interface adhesion, and the cellulose reinforcing agent can improve the tensile strength and elastic modulus of the interface layer.

[0062] In some embodiments provided by the fourth aspect, the thickness ratio of the positive electrode active material layer to the positive electrode interface layer is (8-10): 1. The thickness ratio of the positive electrode active material layer to the positive electrode interface layer in this range can improve the ion-conducting performance of the positive electrode interface, reduce impedance, reduce the occupation of the positive electrode active material, and reduce the impact on the energy density of the battery; and / or, The thickness of the positive electrode interface layer is 3-10 pm. The thickness of the positive electrode interface layer in this range can improve the ion conduction performance of the positive electrode interface, reduce the impedance, reduce the occupation of the positive electrode active material, and reduce the impact on the energy density of the battery.

[0063] In combination with the fourth aspect, in some embodiments provided in the present application, in the positive electrode interface layer, the mass fraction of the solid-state electrolyte decreases from the direction close to the positive electrode active material layer to the direction away from the positive electrode active material layer. The decreasing mass fraction of the solid-state electrolyte can form a continuous ion channel, improve the ion conduction capacity, and can be realized by the electrostatic spraying field dominant deposition gradient. The voltage at the nozzle is +20 kV (positive electrode side), and the voltage at the substrate is -5 kV (electrolyte side), to form a potential gradient. The positively charged solid-state electrolyte particles are driven by the electric field force to deposit at a higher density (70%±5%) on the positive electrode side and decrease to (50%±5%) on the electrolyte side. The gradient is formed by the uneven spatial distribution of the electric field. At the same time, the temperature difference of the hot press plate is set, the positive electrode side is (70-80 ℃), and the electrolyte side is (40-60 ℃). The viscosity of the flexible matrix decreases at the high temperature side, and the molecular chain movement intensifies. Therefore, the flow of the flexible matrix further drives the solid-state electrolyte particles to migrate to the low temperature side, strengthening the gradient distribution.

[0064] In the fifth aspect, the present application provides a solid-state electrolyte including a nano solid-state electrolyte, a flexible matrix, a lithium salt, and a cellulose reinforcing agent. Adding the flexible matrix and the cellulose reinforcing agent to the solid-state electrolyte can inhibit electrolyte cracking, reduce cracks, reduce ion channel breakage, and reduce interface impedance. The lithium salt can construct a lithium ion migration channel and improve ion transmission capacity.

[0065] In combination with the fifth aspect, in some embodiments provided in the present application, the solid-state electrolyte includes at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide, and oxide-polymer composite electrolyte. Using any of the above solid-state electrolytes can improve the stability of the solid-state electrolyte and reduce the probability of side reactions.

[0066] In combination with the fifth aspect, in some embodiments provided in the present application, the flexible matrix includes at least one of polyethylene oxide, polypropylene oxide, and polypropylene oxide. Using at least one of the above flexible matrices can provide a lithium ion migration channel.

[0067] In combination with the fifth aspect, in some embodiments provided in the present application, the lithium salt includes at least one of bis-sulfonimide lithium salt and borate lithium salt. Using at least one of the above lithium salts can maintain high ion conductivity in the bulk phase.

[0068] In some embodiments of the fifth aspect, the cellulose reinforcing agent includes at least one of plant-derived nanocellulose (CNC) and bacterial-derived nanocellulose (BNC). The use of at least one of the above cellulose reinforcing agents can inhibit electrolyte cracking.

[0069] In some embodiments of the fifth aspect, the mass ratio of the nanosolid-state electrolyte, the flexible matrix, the lithium salt, and the cellulose reinforcing agent is (55-65):(20-30):(5-15):(4-5). The mass ratio of the nanosolid-state electrolyte, the flexible matrix, the lithium salt, and the cellulose reinforcing agent in this range can balance the conductivity, flexibility, and mechanical strength.

[0070] In the sixth aspect, the present application provides a solid-state battery, including a negative electrode sheet, a separator, and a positive electrode sheet arranged in sequence, wherein the negative electrode sheet includes the negative electrode sheet of the second aspect, the positive electrode sheet includes the positive electrode sheet of the fourth aspect, and the solid-state battery includes the solid-state battery of the fifth aspect.

[0071] The porous self-repairing layer on the negative electrode side can inhibit the expansion of the silicon-based material, while repairing the cracks generated, repairing the broken ion channels, and reducing the interfacial resistance. The second lithium salt in the solid-state electrolyte can reduce the decomposition of the second lithium salt in the bulk phase, and improve the stability of the electrolyte. The second lithium salt in the positive electrode interfacial layer preferentially forms a dense CEI layer on the positive electrode surface, inhibits the positive electrode interfacial side reaction, reduces gas production, while the first lithium salt increases the lithium ion transference number, reduces the interfacial impedance, and when the positive electrode interfacial solid-state electrolyte nanocrystal seeds are arranged in a gradient, the solid-state electrolyte nanoparticles of the composite electrolyte main body are uniformly distributed to form a conductive path, thereby reducing the overall impedance. Thus, the positive electrode, the negative electrode, and the separator work together to reduce the battery impedance.

[0072] In the seventh aspect, the present application provides an electric device including the solid-state battery of the sixth aspect.

[0073] The technical solutions provided by the present application will be described in detail below with reference to the embodiments.

[0074] Embodiments 1-3 Embodiments 1-3 of the present application provide a negative electrode interfacial self-repairing layer material, including a porous material and a self-repairing material, wherein the porous material includes a porous electrolyte; the self-repairing material includes a core layer material and a shell layer material at least partially coated on the surface of the core layer material; the core layer material includes a thiol-olefin repairing agent and a photoinitiator; and the shell layer material includes a self-repairing polymer. The specific parameters are shown in Table 1: Table 1: Parameters of the negative electrode interfacial self-repairing layer material of embodiments 1-3

[0075] The negative electrode interface self-repairing layer material provided in embodiments 1 to 3 can be prepared by the following preparation method: Mixing the solutions of the self-repairing core layer and the self-repairing shell layer, spray drying to obtain the self-repairing material, spray pressure 0.2 MPa, inlet temperature 120℃, outlet temperature 60℃, self-repairing material loading 5wt%; Mixing the porous electrolyte and the self-repairing material to obtain the negative electrode interface self-repairing layer material.

[0076] Embodiments 4 to 6 Embodiments 4 to 6 of the present application provide a negative electrode sheet, which comprises a current collector, a silicon-based negative electrode active material layer arranged on at least one side of the current collector, and a self-repairing layer arranged on the side of the silicon-based negative electrode active material layer away from the current collector, wherein the material of the self-repairing layer is shown in Table 2.

[0077] Table 2 Material parameters of the negative electrode sheet of embodiments 4 to 6

[0078] Embodiments 4 to 6 provide a negative electrode sheet which can be prepared by the following preparation method: Coating negative electrode active material (SiOx / C composite material) on both sides of the negative electrode current collector (copper foil) to form a negative electrode active material layer; Coating a porous electrolyte mixed solution (solvent tetrahydrofuran (THF)) on the surface of the negative electrode active material layer; setting a gradient temperature field, heating the side close to the negative electrode active layer to 80-90℃, and cooling the side away from the negative electrode active layer (electrolyte side) to 40-50℃ to obtain a gradient distribution of pore structure; heat treatment at 80℃ for 30min under Ar atmosphere to remove residual solvent and stabilize the pore structure, forming a porous electrolyte layer with a porosity changing from 25%~30% to 8%~20% from the negative electrode active material layer to the electrolyte layer; In-situ solidification of self-repairing material on the surface of the porous electrolyte layer, process parameters: 1) UV light (wavelength 365nm, intensity 50mW / cm², time 10min), triggering thiol-ene click chemistry reaction to form a crosslinked network; 2) 80℃ / 15min to strengthen the interface bonding to form a self-repairing layer, obtaining a negative electrode sheet.

[0079] Embodiments 7 to 9 Embodiments 7 to 9 of the present application provide a positive electrode interface material, which comprises a solid-state electrolyte, a flexible matrix, a composite lithium salt, and a cellulose reinforcing agent, wherein: the composite lithium salt comprises a first lithium salt and a second lithium salt, the first lithium salt has dissociability, and the second lithium salt has film-forming property; the solid-state electrolyte is in the form of nanocrystalline seeds. The positive electrode interface material is shown in Table 3.

[0080] Table 3 Material parameters of the positive electrode interface material of embodiments 7 to 9

[0081] The positive electrode interface material provided in Examples 7 to 9 can be prepared by the following method: The solid-state electrolyte, flexible matrix, composite lithium salt and cellulose reinforcing agent are dispersed in acetonitrile solvent with a solid content of 10%, and the positive electrode interface material is obtained by spray drying.

[0082] Examples 10 to 12 The application provides a positive electrode sheet in Examples 10 to 12, which comprises a current collector, a positive electrode active material layer arranged on at least one side of the current collector, and a positive electrode interface layer arranged on a side of the positive electrode active material layer away from the current collector, wherein the material of the positive electrode interface layer is shown in Table 4.

[0083] Table 4 Parameters of the positive electrode sheet in Examples 10 to 12

[0084] The positive electrode sheet provided in Examples 10 to 12 can be prepared by the following method: Preparation of positive electrode slurry: NCM9 (lithium nickel cobalt manganese oxide, wherein the content of nickel is 90%) (90%), conductive carbon black (5%) and PVDF binder (5%) are mixed in NMP solvent, and coated on an aluminum foil (areal density 20 mg / cm²).

[0085] Deposition of interface layer: a gradient double-salt interface layer (areal density 2 mg / cm², corresponding to a dry film thickness of 3 μm) is deposited by electrostatic spraying, the voltage at the nozzle is +20 kV (positive electrode side), and the voltage of the substrate is -5 kV (electrolyte side), forming a potential gradient, and the positively charged solid-state electrolyte particles are driven by the electric field force to deposit at a higher density (70%±5%) on the positive electrode side and decrease to (50%±5%) on the electrolyte side, and the gradient is formed by the uneven spatial distribution of the electric field. At the same time, the temperature difference of the hot press plate is set, the positive electrode side is (70~80 ℃), and the electrolyte side is (40~60 ℃), the cooling rate is 2 ℃ / min, the pressure is 15 MPa, and the time is 30 min. The viscosity of the flexible matrix decreases at the high-temperature side, and the molecular chain movement intensifies, so that the flow of the flexible matrix further drives the solid-state electrolyte particles to migrate to the low-temperature side, and the gradient distribution is strengthened. Then, UV curing (wavelength 365 nm, intensity 50 mW / cm², time 10 min) is performed to form a positive electrode interface layer, and a positive electrode sheet is obtained.

[0086] Examples 13 to 15 The application provides a solid-state electrolyte in Examples 13 to 15, which comprises a nano solid-state electrolyte, a flexible matrix, a lithium salt and a cellulose reinforcing agent, and the parameters of the solid-state electrolyte are shown in Table 5.

[0087] Table 5 Parameters of the solid-state electrolyte in Examples 13 to 15

[0088] The solid-state electrolyte provided in Examples 13 to 15 can be prepared into a composite separator by the following method: The nanosolid-state electrolyte, flexible matrix, lithium salt, and cellulose reinforcing agent were ball-milled at a speed of 300 rpm for 2 h to obtain a solid-state electrolyte.

[0089] The mixed solid-state electrolyte slurry was coated on both sides of a PE-based film (thickness 16 pm, porosity 40%) to form a single layer of wet film with a thickness of 100 pm.

[0090] The solid-state electrolyte layer was densified by hot pressing at a temperature of 100°C and a pressure of 15 MPa for 1 h, and the single layer of dry film had a thickness of 5 pm, and the total separator had a thickness of 26 pm, thereby obtaining a composite separator.

[0091] Examples 16 to 18 The solid-state battery provided in Examples 16 to 18 has the specific parameters shown in Table 6.

[0092] Table 6: Parameters of the solid-state battery of Examples 16 to 18

[0093] The solid-state battery provided in Examples 16 to 18 can be assembled by the following method: The positive electrode sheet, composite separator, and negative electrode sheet were stacked and hot pressed (100°C, 15 MPa, 30 min), and a LiPF6 / EC-DMC solution containing an initiator was injected to form a gel electrolyte by in-situ solidification at 80°C for 30 min, and the solid-state battery was packaged.

[0094] Comparative Example 1 The negative electrode interface self-repairing material provided in Comparative Example 1 is similar to Example 3, except that it does not contain a self-repairing material.

[0095] Comparative Example 2 The positive electrode interface material provided in Comparative Example 2 is similar to Example 9, except that it does not contain a composite lithium salt and a cellulose reinforcing agent.

[0096] Comparative Example 3 The solid-state electrolyte provided in Comparative Example 3 is similar to Example 15, except that it does not contain a flexible matrix, lithium salt, and cellulose reinforcing agent.

[0097] Comparative Example 4 The solid-state battery provided in Comparative Example 4 is similar to Example 18, except that it uses the negative electrode interface self-repairing material provided in Comparative Example 1.

[0098] Comparative Example 5 The present application provides a solid-state battery for Comparative Example 5, which is similar to Example 18, except that the positive electrode interface material provided in Comparative Example 2 is used.

[0099] Comparative Example 6 The present application provides a solid-state battery for Comparative Example 6, which is similar to Example 18, except that the solid-state electrolyte provided in Comparative Example 3 is used.

[0100] Comparative Example 7 The present application provides a solid-state battery for Comparative Example 7, which is similar to Example 18, except that the negative electrode sheet does not contain a self-repairing layer, the positive electrode sheet does not contain a positive electrode interface layer, and the solid-state electrolyte does not contain a flexible matrix, a lithium salt, and a cellulose reinforcing agent.

[0101] Performance test The solid-state batteries of Examples 16 to 18 and Comparative Examples 4 to 7 were subjected to electrical performance tests, and the specific steps were as follows: Impedance test method: An electrochemical workstation was used to perform EIS tests at 25°C and 50% SOC, with a frequency range of 0.1 Hz-1 MHz and an amplitude of 10 mV.

[0102] Silicon negative electrode expansion rate test method: Under constant pressure and constant temperature (usually 25±1°C) environment, the thickness change rate of the battery from initial state (0% SOC) to final state (100% SOC) was measured.

[0103] Charge-discharge energy efficiency test method: Under constant current charge-discharge conditions, the charge input energy Ec and discharge output energy Ed were accurately measured, and the efficiency value was calculated according to the formula η=Ed / Ec×100%. The test needs to control the temperature (usually 25°C±5°C) and the SOC state (such as 50%), and the current fluctuation needs to be <1%.

[0104] Cycle capacity retention rate test method: 1) The battery was subjected to 3 times of standard charge-discharge, and was left to reach thermal equilibrium, and the last discharge capacity was taken as C0; (25°C±1°C); 2) The battery was subjected to standard discharge after DC internal resistance test; 3) The full battery was subjected to multiple charge-discharge cycles at a standard current (such as 1C) at 25°C±1°C, and the discharge capacity Ct was measured periodically, the retention rate was calculated according to the formula η=Ct / C0×100%, and the termination threshold (≥80%) was verified.

[0105] The specific test results are shown in Table 7: Table 7 Performance of solid-state batteries of Examples 16 to 18 and Comparative Examples 4 to 7

[0106] As can be seen from Table 7, the solid-state batteries of Examples 16 to 18 have lower interface impedance, suppressed expansion rate, and higher energy efficiency.

[0107] Comparative Example 4 has the defects of interface impedance rising, silicon expansion intensifying and capacity retention rate plummeting due to the absence of self-repairing material in the negative electrode interface self-repairing material.

[0108] Comparative Example 5 has the defects of interface impedance rising and gas production risk intensifying due to the absence of composite lithium salt and cellulose reinforcing agent in the positive electrode interface material.

[0109] Comparative Example 6 has the defects of poor interface contact and high expansion rate due to the absence of flexible matrix, lithium salt and cellulose reinforcing agent in the solid-state electrolyte.

[0110] Comparative Example 7 has the defects of high impedance, high expansion rate and low capacity retention rate due to the absence of any improvement to the positive electrode sheet, negative electrode sheet and solid-state battery.

[0111] In summary, the porous electrolyte can inhibit silicon expansion, construct ion-conducting channels, reduce interface impedance, and has stable chemical properties and compatibility with silicon-based materials, which can reduce the occurrence of side reactions. The thiol-ene click chemical reaction (Thiol-Ene Click Reaction) between the olefin monomer (such as trimethylolpropane triacrylate / pentaerythritol tetraacrylate) and the thiol monomer (such as pentaerythritol tetra(3-mercaptopropionate)) forms a three-dimensional network under the catalysis of a photoinitiator, which can trigger in-situ crosslinking to repair interface cracks quickly and dynamically, reduce the breakage of ion-conducting channels, and thus reduce interface impedance.

[0112] In the description of the present specification, the description of the terms "one embodiment / way", "some embodiments / ways", "example", "specific example" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment / way or example are included in at least one embodiment / way or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment / way or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments / ways or examples. In addition, the person skilled in the art can combine and combine the different embodiments / ways or examples described in the present specification and the features of the different embodiments / ways or examples without contradiction.

[0113] It has to be noted that, in the present application, terms like "first", "second", and the like in the description and in the claims are used to distinguish between similar elements and not necessarily to describe a sequential or chronological order. Furthermore, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the presence of additional identical elements in the process, method, article, or apparatus that comprises the element. The term "plurality" denotes two or more, for example two, three or four unless expressly specified otherwise.

[0114] The foregoing is considered as illustrative only of the principles of the application. Numerous modifications and changes will readily occur to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Accordingly, the scope of the application is indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.

Claims

1. A negative electrode interface self-repairing material, characterized in that: Includes porous materials and self-healing materials, including: The porous material includes a porous electrolyte; The self-repairing material comprises a core layer material and a shell layer material at least partially coated on the surface of the core layer material; The core layer material includes a thiol-olefin repair agent and a photoinitiator; The shell material includes a self-healing polymer.

2. The negative electrode interface self-repairing material according to claim 1, wherein: The porous electrolyte includes at least one of a sulfide electrolyte and a polymer electrolyte; and / or, The porosity of the porous electrolyte is 20% to 40%; and / or, The porous electrolyte has an ionic conductivity at 25° C. greater than or equal to 0.1 m S / cm.

3. The negative electrode interface self-repairing material according to claim 1, wherein: The thiol-olefin repair agent comprises at least one of the reaction products of a thiol-based compound and an olefin-based monomer; and / or, The photoinitiator comprises at least one of TPO, Irgacure 819, Irgacure 184, and Darocur 1173; and / or, The self-repairing polymer comprises at least one of polyurethane acrylate, polysulfide ether, disulfide bond-crosslinked polyurethane and acylhydrazone bond-crosslinked polyurethane; and / or, The diameter of the core layer is 150-250 nm; and / or, The thickness of the shell layer is 40-60 nm; and / or, The mass ratio of the thiol-olefin repair agent to the photoinitiator is (90-99):1; and / or, The mass ratio of the porous material to the self-healing material is (10~19):

1.

4. A negative electrode sheet, characterized in that: It includes a current collector, a silicon-based negative electrode active material layer provided on at least one side of the current collector, and a self-repairing layer provided on the side of the silicon-based negative electrode active material layer away from the current collector, wherein the material of the self-repairing layer includes the negative electrode interface self-repairing material according to any one of claims 1 to 3.

5. The negative electrode sheet according to claim 4, wherein: The thickness ratio of the silicon-based negative electrode active material layer to the self-repairing layer is (9-11):1; and / or, The thickness of the self-repairing layer is 1-5 μm.

6. A positive electrode interface material, characterized in that It includes a solid electrolyte, a flexible matrix, a composite lithium salt and a cellulose reinforcing agent, wherein: The composite lithium salt includes a first lithium salt and a second lithium salt, the first lithium salt is dissociable, and the second lithium salt is film-forming; The solid electrolyte is in a nanocrystalline seed state.

7. The positive electrode interface material according to claim 6, wherein: The solid electrolyte comprises at least one of lithium titanium aluminum phosphate, lithium germanium aluminum phosphate, lithium lanthanum zirconium oxide, lithium lanthanum zirconium oxide-polyethylene oxide, and lithium titanium aluminum phosphate-polypropylene oxide; and / or, The particle size of the solid electrolyte is 10-200 nm; and / or, The ionic conductivity of the solid electrolyte at 25° C. is ≥0.1 m S / cm; and / or, The flexible matrix comprises at least one of polyethylene oxide, polypropylene oxide and polypropylene oxide; and / or, The molecular weight of the flexible matrix is ​​greater than or equal to 400 kDa; and / or, The lithium ion transference number of the flexible substrate is greater than or equal to 0.4; and / or, The cellulose reinforcing agent comprises at least one of plant-derived nanocellulose and bacterial-derived nanocellulose; and / or, The fiber length of the cellulose reinforcing agent is 0.05-1 μm; and / or, The fiber diameter of the cellulose reinforcing agent is 40-70 nm.

8. The positive electrode interface material according to claim 6, wherein: The first lithium salt includes at least one of a bissulfonyl imide lithium salt and a borate lithium salt; and / or, The second lithium salt includes at least one of a fluorine-containing lithium phosphate salt, an oxalate lithium salt and a boron-containing lithium salt; and / or, The mass ratio of the first lithium salt to the second lithium salt is (3-5):1; and / or, The mass ratio of the solid electrolyte, the flexible matrix, the composite lithium salt and the cellulose reinforcing agent is (65-75): (20-30): (0.5-1): (4-4.5).

9. A positive electrode sheet, characterized in that: It comprises a current collector, a positive electrode active material layer provided on at least one side of the current collector, and a positive electrode interface layer provided on a side of the positive electrode active material layer away from the current collector, wherein the material of the positive electrode interface layer comprises the positive electrode interface material according to any one of claims 6 to 8.

10. The positive electrode sheet according to claim 9, wherein: The thickness ratio of the positive electrode active material layer to the positive electrode interface layer is (8-10):1; and / or, The thickness of the positive electrode interface layer is 3-10 μm.

11. The positive electrode sheet according to claim 9, wherein: In the positive electrode interface layer, the mass proportion of the solid electrolyte is arranged to decrease from the direction close to the positive electrode active material layer to the direction away from the positive electrode active material layer.

12. A solid electrolyte, characterized in that It includes nano solid electrolyte, flexible matrix, lithium salt and cellulose reinforcing agent, among which: The solid electrolyte comprises at least one of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide, lithium lanthanum zirconium oxide-polyethylene oxide-lithium bis(trifluoromethanesulfonyl)imide and lithium aluminum germanium phosphate-polyethylene oxide-nanocellulose composite; and / or, The flexible matrix comprises at least one of polyethylene oxide, polypropylene oxide and polypropylene oxide; and / or, The lithium salt includes at least one of a bissulfonyl imide lithium salt and a borate lithium salt; and / or, The cellulose reinforcing agent includes at least one of plant-derived nanocellulose and bacterial-derived nanocellulose.

13. The solid electrolyte according to claim 12, wherein: The mass ratio of the nano solid electrolyte, the flexible matrix, the lithium salt and the cellulose reinforcing agent is (55-65): (20-30): (5-15): (1-10).

14. A solid-state battery, characterized in that: It includes a negative electrode sheet, a separator and a positive electrode sheet arranged in sequence, wherein: The negative electrode sheet includes the negative electrode sheet according to claim 4; The positive electrode sheet includes the positive electrode sheet according to claim 9; The diaphragm includes an isolation membrane and solid electrolyte layers provided on both sides of the isolation membrane, and the material of the solid electrolyte layer includes the solid electrolyte according to claim 12.

15. An electrical device, characterized in that: Including the solid-state battery as described in claim 14.

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