Solid-state battery and preparation method of composite solid electrolyte thereof

Abstract

According to the solid-state battery and the preparation method of the composite solid-state electrolyte of the solid-state battery, the surface of an electrolyte membrane is covered with a layer of first composite material, Li2O-B2O3 is stable to high voltage, B2O3 can effectively'capture 'or'fix' active hydrogen generated by decomposition of LiBH4 and prevent the active hydrogen from damaging an interface of a positive plate, a LiBH4 derivative phase is soft in texture, and the composite solid-state electrolyte of the solid-state battery can be used for a lithium ion battery. LiBH4 is added into the solid electrolyte, so that gaps between positive electrode particles and the solid electrolyte can be filled, the interface impedance is greatly reduced, and LiBH4 has high ionic conductivity and can maintain relatively good lithium conductivity; a layer of second composite material covers the surface of the composite solid electrolyte, and Li4PS4 provides high conductivity, has a very wide electrochemical stable window, can be directly and stably contacted with a high-voltage positive electrode, effectively inhibits release of positive electrode active oxygen and interface side reaction, and can effectively block diffusion of transition metal ions in the positive electrode to the electrolyte side; and moreover, the two layers of composite materials are used as bridging layers by introducing Li2S, so that the firm connection of the two composite layers is realized, and the impedance is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of solid-state batteries, in particular to a solid-state battery and a preparation method of a composite solid-state electrolyte thereof. BACKGROUND

[0002] In recent years, with the rapid development of new energy technology, batteries as an important energy storage medium and power source for portable electronic devices play an increasingly key role in the industrial field. Among them, lithium ion batteries have become the most ideal portable power solution at present due to their excellent energy density and power density advantages. However, the traditional liquid lithium ion battery has a major safety problem due to containing a large amount of flammable organic electrolyte. In order to fundamentally solve this problem, all-solid-state lithium batteries are becoming the forefront of global battery technology research and development, and are also the key path to break through the energy density bottleneck and thermal runaway risk of current liquid lithium ion batteries.

[0003] Developing all-solid-state lithium batteries with high safety and high energy density is considered as an important direction to break through the energy density limit and thermal runaway risk of current liquid lithium ion batteries. Among various solid-state electrolyte materials, sulfide electrolyte is considered as one of the technical routes with greater potential for commercial application due to its extremely high ionic conductivity and good mechanical properties. However, the interface problem between sulfide electrolyte and positive electrode material, such as severe side reaction and positive electrode particle crack propagation, all lead to a substantial increase in the interface impedance of the battery, thereby making the cycle performance of the battery worse, which seriously restricts its actual application. Therefore, it is necessary to propose a new scheme to solve the above problems. SUMMARY

[0004] Therefore, the present application aims at the defects in the prior art, and the main purpose is to provide a solid-state battery and a preparation method of a composite solid-state electrolyte thereof, which can effectively solve the interface problem between the sulfide solid-state electrolyte and the positive electrode material of the existing solid-state battery, the severe side reaction and the positive electrode particle crack propagation all lead to a substantial increase in the interface impedance of the battery, thereby making the cycle performance of the battery worse, which seriously restricts its actual application.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows: A preparation method of a composite electrolyte, comprising the following steps: (1) dissolving LiOH H2O and H3BO3 in deionized water, the molar ratio of LiOH H2O to H3BO3 is 2:1, and then adding a thickening agent, the amount of the thickening agent being 0.5% to 1% of the amount of LiOH H2O and H3BO3total mass of 1%, followed by 80℃, backflow reaction, stirring rate of 300r / min, reaction time 2h, after cooling, ultrasonic dispersion 20min, obtain Li2O-B2O3sol; to Li2O-B2O3sol, add 0.1mol / L LiBH4solution, LiBH4and Li2O-B2O3mass ratio is 1:4, in the atmosphere of inert gas, stirring 1h, dropwise add anhydrous ether to have particle precipitation, again by spray dryer to form a spherical particle, then, in the atmosphere of inert gas, with 5℃ / min heating rate, heating to 200℃, calcination 2h, again natural cooling to 150℃, annealing 1-2h, get the first composite material; (2) Li3PS4 powder and anhydrous ethanol mixture, Li3PS4 powder and anhydrous ethanol mass ratio is 1:10, add PEG-2000, PEG-2000 dosage is 0.5% of Li3PS4 powder and anhydrous ethanol total mass, ultrasonic dispersion 30-60min, obtain suspension; to the suspension, drop LiH2PO4ethanol solution, drop rate is 1mL / min, LiH2PO4ethanol solution concentration is 0.2mol / L, until LiH2PO4and Li3PS4mass ratio is 1:5, with ammonia water to adjust pH to 7.5-8.0, at 40℃, stirring rate of 500r / min, stirring 2-5h, get Li3PS4@Li3PO4sol, Li3PS4@Li3PO4sol by spray dryer to form a spherical particle, then, in the atmosphere of inert gas, with 5℃ / min heating rate, heating to 200℃, calcination 2h, after cooling, get the second composite material; (3) Li2S powder and anhydrous ethanol mixture, Li2S powder and anhydrous ethanol mass ratio is 1:20, add tetrabutyl titanate, tetrabutyl titanate dosage is 0.3% of Li2S powder and anhydrous ethanol total mass, ultrasonic dispersion 15min, get bridging slurry; (4) in the argon glove box, first, the first composite material obtained in step (1) is evenly spread on one surface of the electrolyte membrane, then the bridging slurry obtained in step (3) is sprayed to form a wet film, then the second composite material obtained in step (2) is evenly spread on the aforementioned wet film to obtain a composite solid-state electrolyte embryo; the composite solid-state electrolyte embryo is placed in a tube furnace, heated to 100℃ under the atmosphere of inert gas, and the solvent is removed after 1h of heat preservation, then heated to 250℃ for 2h of heat preservation, and after natural cooling, Li2S reacts with Li3PO4 to form Li3PO4-Li2S solid solution, and Li2S reacts with LiBH4 to form Li2S-B2S3 bonding phase, realizing seamless connection of the interface, to obtain a composite solid-state electrolyte.

[0006] As a preferred solution, in step (1), the thickening agent is gum arabic.

[0007] As a preferred solution, in step (1), the inert gas is nitrogen or argon.

[0008] As a preferred solution, in step (2), the inert gas is nitrogen or argon.

[0009] As a preferred solution, in step (4), the electrolyte membrane is a UDSH-modified LPSC membrane.

[0010] As a preferred solution, in step (4), the water and oxygen content of the argon glove box is ≤0.1 ppm.

[0011] As a preferred solution, in step (1) and step (2), the inlet temperature of the spray dryer is 120℃, the outlet temperature is 60℃, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0012] As a preferred solution, in step (4), the thickness of the wet membrane is 10 μm.

[0013] A preparation method of a solid-state battery, comprising the following steps: (a) preparing a negative electrode sheet; (b) preparing a positive electrode sheet; (c) stacking the positive electrode sheet, the composite solid-state electrolyte, and the negative electrode sheet in order to obtain an electric core, the composite solid-state electrolyte being prepared by the aforementioned preparation method of a composite electrolyte, and the negative electrode sheet being attached to the other surface of the electrolyte membrane, and then performing pressure densification on the electric core at room temperature, with a pressure of 10 MPa and a pressure maintaining time of 5 min, followed by performing pressure densification on the electric core at 80℃, with a pressure of 50 MPa and a pressure maintaining time of 20 min, to obtain a solid-state battery.

[0014] As a preferred solution, the preparation process of the positive electrode sheet is as follows: The lithium nickel cobalt manganese oxide coated with LiNbO3 on the surface is used as the positive electrode active material, the content of LiNbO3 is 1 wt%, Li6PS5C is used as the positive electrode solid-state electrolyte, carbon nanotubes are used as the positive electrode conductive agent, PAA is used as the positive electrode binder, and p-xylene is used as the positive electrode solvent, the positive electrode active material, the positive electrode solid-state electrolyte, the positive electrode conductive agent, and the positive electrode binder are mixed uniformly at a mass ratio of 80:18:1:2, the positive electrode solvent is added, a positive electrode slurry is obtained, the positive electrode slurry is coated on the positive and negative sides of an aluminum foil, and then the positive electrode sheet is obtained after rolling, drying, and cutting; the negative electrode sheet is a lithium metal sheet.

[0015] Compared with the prior art, the present application has obvious advantages and beneficial effects, specifically, from the above technical solution, it can be known that: By covering a layer of first composite material on the surface of the electrolyte membrane, the first composite material is a Li2O-B2O3@LiBH4 derived phase core-shell structure, Li2O-B2O3 is stable to high voltage itself, B2O3 can effectively "capture" or "fix" active hydrogen generated by LiBH4 decomposition, prevent it from causing damage to the interface of the positive plate, LiBH4 derived phase is relatively soft, which can fill the gap between the positive plate particles and the solid-state electrolyte, realize excellent physical contact, greatly reduce the interface impedance, reduce the problem of falling off in the subsequent charging and discharging process, LiBH4 has high ionic conductivity and can maintain good lithium ion conductivity; in combination with the surface covering of the composite solid-state electrolyte with a layer of second composite material, the second composite material is a Li3PS4@Li3PO4 structure, Li4PS4 provides high conductivity and has a very wide electrochemical stability window, which can directly and stably contact with the high-voltage positive plate, effectively inhibits the release of positive active oxygen and the interface side reaction, and effectively blocks the diffusion of transition metal ions such as Co, Mn and Ni in the positive plate to the electrolyte side; and, the two layers of composite materials are connected by introducing Li2S as a bridge layer, Li2S reacts with Li3PO4 to form a Li3PO4-Li2S solid solution, Li2S and LiBH4 derived phase form a Li2S-B2S3 combined phase, realizing firm connection of the two composite layers, reducing impedance, and avoiding falling off in the subsequent charging and discharging process.

[0016] To make the structural features and effects of the present application clearer, the present application will be described in detail below in combination with specific examples. DETAILED DESCRIPTION

[0017] The present application discloses a preparation method of a composite electrolyte, comprising the following steps: (1) dissolving LiOH H2O and H3BO3 in deionized water, the molar ratio of LiOH H2O and H3BO3 is 2:1, and then adding a thickening agent, the amount of the thickening agent is 2% of LiOH H2O and H3BO3 total mass of 1%, followed by 80 ℃, backflow reaction, stirring rate of 300 r / min, reaction time 2 h, after cooling, ultrasonic dispersion 20 min, Li2O-B2O3 sol; to Li2O-B2O3 sol, 0.1 mol / L LiBH4 solution, LiBH4 and Li2O-B2O3 mass ratio of 1:4, in the inert gas atmosphere, stirring 1 h, dropwise addition of anhydrous ether to have particles precipitate, again by spray dryer to form spherical particles, then, in the inert gas atmosphere, with 5 ℃ / min heating rate, heated to 200 ℃, calcined 2 h, again natural cooling to 150 ℃, annealing 1-2 h, to obtain the first composite material; the thickening agent is gum arabic, the inert gas is nitrogen or argon, the inlet temperature of the spray dryer is 120 ℃, the outlet temperature is 60 ℃, the pressure is 0.3 MPa, the feeding rate is 5 mL / min.

[0018] (2) Li3PS4 powder and anhydrous ethanol were mixed, the mass ratio of Li3PS4 powder to anhydrous ethanol was 1:10, PEG-2000 was added, the amount of PEG-2000 was 0.5% of the total mass of Li3PS4 powder and anhydrous ethanol, and ultrasonic dispersion was performed for 30-60 min to obtain a suspension; LiH2PO4 ethanol solution was added dropwise to the suspension, the dropwise speed was 1 mL / min, the concentration of LiH2PO4 ethanol solution was 0.2 mol / L, until the mass ratio of LiH2PO4 to Li3PS4 was 1:5, the pH was adjusted to 7.5-8.0 with ammonia water, and stirring was performed at 40 ℃ and a stirring speed of 500 r / min for 2-5 h to obtain a Li3PS4@Li3PO4 sol, the Li3PS4@Li3PO4 sol was formed into spherical particles by a spray dryer, then, in the inert gas atmosphere, heated to 200 ℃ at a heating rate of 5 ℃ / min, calcined for 2 h, and after cooling, a second composite material was obtained; the inert gas was nitrogen or argon, the inlet temperature of the spray dryer was 120 ℃, the outlet temperature was 60 ℃, the pressure was 0.3 MPa, and the feeding rate was 5 mL / min.

[0019] (3) Li2S powder and anhydrous ethanol were mixed, the mass ratio of Li2S powder to anhydrous ethanol was 1:20, tetrabutyl titanate was added, the amount of tetrabutyl titanate was 0.3% of the total mass of Li2S powder and anhydrous ethanol, and ultrasonic dispersion was performed for 15 min to obtain a bridging slurry; (4) In an argon glove box, the first composite material obtained in step (1) is uniformly spread on one surface of the electrolyte membrane, and the bridging slurry obtained in step (3) is sprayed to form a wet film, then the second composite material obtained in step (2) is uniformly spread on the wet film to obtain a composite solid-state electrolyte embryo; the composite solid-state electrolyte embryo is placed in a tube furnace, heated to 100℃ under an inert gas atmosphere, and kept for 1h to remove the solvent, then heated to 250℃ and kept for 2h, and after natural cooling, Li2S and Li3PO4 react to form a Li3PO4-Li2S solid solution, and Li2S and LiBH4 react to form a Li2S-B2S3 bonding phase, realizing seamless connection of the interfaces, to obtain a composite solid-state electrolyte; the electrolyte membrane is a LPSC membrane modified by UDSH, the water and oxygen content of the argon glove box is ≤0.1ppm, and the thickness of the wet film is 10μm.

[0020] The application also discloses a preparation method of a solid-state battery, which comprises the following steps: (a) preparing a negative electrode sheet, wherein the negative electrode sheet is a lithium metal sheet.

[0021] (b) preparing a positive electrode sheet, wherein LiNbO3-coated lithium nickel cobalt manganese oxide is used as a positive electrode active material, the content of LiNbO3 is 1wt%, Li6PS5C is used as a positive electrode solid-state electrolyte, a nanometer carbon tube is used as a positive electrode conductive agent, PAA is used as a positive electrode binder, and p-xylene is used as a positive electrode solvent; the positive electrode active material, the positive electrode solid-state electrolyte, the positive electrode conductive agent and the positive electrode binder are uniformly mixed according to a mass ratio of 80:18:1:2, then the positive electrode solvent is added to obtain a positive electrode slurry, and the positive electrode slurry is coated on the positive and negative sides of an aluminum foil, and then roll-pressed, dried and cut to obtain the positive electrode sheet.

[0022] (c) stacking the positive electrode sheet, the composite solid-state electrolyte and the negative electrode sheet in sequence to obtain a battery cell, wherein the composite solid-state electrolyte is prepared by the preparation method of the composite electrolyte; the negative electrode sheet is attached to the other surface of the electrolyte membrane; the battery cell is first densified at room temperature under a pressure of 10MPa for 5min, and then densified at 80℃ under a pressure of 50MPa for 20min to obtain the solid-state battery.

[0023] The application will be described in detail below in combination with multiple examples and comparative examples.

[0024] Example 1 (1) LiOH H2O and H3BO3 are dissolved in deionized water, and the molar ratio of LiOH H2O to H3BO3 is 2:1, and a thickening agent is further added, and the amount of the thickening agent is 1wt% of LiOH H2O and H3BO3 total mass of 1%, followed by 80 ℃, backflow reaction, stirring rate of 300 r / min, reaction time 2 h, after cooling, ultrasonic dispersion 20 min, Li2O-B2O3 sol is obtained; to Li2O-B2O3 sol is added 0.1 mol / L LiBH4 solution, LiBH4 and Li2O-B2O3 mass ratio is 1:4, in the atmosphere of inert gas, stirring 1 h, dropwise addition of anhydrous ether until there are particles precipitate, and then by spray dryer to form spherical particles, followed by, in the atmosphere of inert gas, to 200 ℃ at a heating rate of 5 ℃ / min, calcination 2 h, and then natural cooling to 150 ℃, annealing 1 h, to obtain the first composite material; the thickening agent is gum arabic, the inert gas is nitrogen, the inlet temperature of the spray dryer is 120 ℃, the outlet temperature is 60 ℃, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0025] (2) Li3PS4 powder and anhydrous ethanol are mixed, the mass ratio of Li3PS4 powder to anhydrous ethanol is 1:10, PEG-2000 is added, the amount of PEG-2000 is 0.5% of the total mass of Li3PS4 powder and anhydrous ethanol, and ultrasonic dispersion is performed for 30 min to obtain a suspension; dropwise addition of LiH2PO4 ethanol solution is performed to the suspension, the dropwise addition rate is 1 mL / min, the concentration of LiH2PO4 ethanol solution is 0.2 mol / L, until the mass ratio of LiH2PO4 to Li3PS4 is 1:5, the pH is adjusted to 7.5 with ammonia water, stirring is performed at 40 ℃ and a stirring rate of 500 r / min for 2 h to obtain a Li3PS4@Li3PO4 sol, the Li3PS4@Li3PO4 sol is formed into spherical particles by a spray dryer, then, in the atmosphere of inert gas, the temperature is raised to 200 ℃ at a heating rate of 5 ℃ / min, calcination is performed for 2 h, and after cooling, a second composite material is obtained; the inert gas is argon, the inlet temperature of the spray dryer is 120 ℃, the outlet temperature is 60 ℃, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0026] (3) Li2S powder and anhydrous ethanol are mixed, the mass ratio of Li2S powder to anhydrous ethanol is 1:20, tetrabutyl titanate is added, the amount of tetrabutyl titanate is 0.3% of the total mass of Li2S powder and anhydrous ethanol, and ultrasonic dispersion is performed for 15 min to obtain a bridging slurry; (4) In an argon glove box, the first composite material obtained in step (1) is uniformly spread on one surface of the electrolyte membrane, and the bridging slurry obtained in step (3) is sprayed to form a wet film. Then, the second composite material obtained in step (2) is uniformly spread on the wet film to obtain a composite solid-state electrolyte embryo. The composite solid-state electrolyte embryo is placed in a tube furnace, heated to 100℃ under an inert gas atmosphere, and kept for 1h to remove the solvent. Then, the temperature is increased to 250℃ and kept for 2h. After natural cooling, Li2S reacts with Li3PO4 to form a Li3PO4-Li2S solid solution, and Li2S reacts with LiBH4 to form a Li2S-B2S3 bonding phase, realizing seamless connection of the interfaces, and obtaining a composite solid-state electrolyte. The electrolyte membrane is a LPSC membrane modified by UDSH, the water and oxygen content of the argon glove box is ≤0.1ppm, and the thickness of the wet film is 10μm.

[0027] (5) A negative electrode sheet is prepared, which is a lithium metal sheet.

[0028] (6) A positive electrode sheet is prepared, using lithium nickel cobalt manganese oxide coated with LiNbO3 as the positive electrode active material, the content of LiNbO3 being 1wt%, using Li6PS5C as the positive electrode solid-state electrolyte, using carbon nanotubes as the positive electrode conductive agent, using PAA as the positive electrode binder, and using p-xylene as the positive electrode solvent. The positive electrode active material, the positive electrode solid-state electrolyte, the positive electrode conductive agent, and the positive electrode binder are uniformly mixed in a mass ratio of 80:18:1:2, and then the positive electrode solvent is added to obtain a positive electrode slurry. The positive electrode slurry is coated on both sides of an aluminum foil, and then rolled, dried, and cut to obtain a positive electrode sheet.

[0029] (7) The positive electrode sheet, the composite solid-state electrolyte, and the negative electrode sheet are stacked in order to obtain a battery cell. The composite solid-state electrolyte is prepared by the above-mentioned method. The negative electrode sheet is attached to the other surface of the electrolyte membrane. The battery cell is first densified at room temperature under a pressure of 10MPa for 5min, and then densified at 80℃ under a pressure of 50MPa for 20min to obtain a solid-state battery.

[0030] Example 2 (1) LiOH H2O and H3BO3 are dissolved in deionized water, and the molar ratio of LiOH H2O to H3BO3 is 2:1. A thickening agent is then added, and the amount of the thickening agent is 1wt% of LiOH H2O and H3BO3 total mass of 1%, followed by 80 ℃, backflow reaction, stirring rate of 300 r / min, reaction time 2 h, after cooling, ultrasonic dispersion 20 min, Li2O-B2O3 sol is obtained; 0.1 mol / L LiBH4 solution is added to Li2O-B2O3 sol, the mass ratio of LiBH4 to Li2O-B2O3 is 1:4, under the atmosphere of inert gas, stirring for 1 h, adding anhydrous ether dropwise until particles are precipitated, then forming spherical particles by spray dryer, then, under the atmosphere of inert gas, heating to 200 ℃ at a heating rate of 5 ℃ / min, calcining for 2 h, then naturally cooling to 150 ℃, annealing for 2 h, to obtain the first composite material; the thickening agent is gum arabic, the inert gas is argon, the inlet temperature of the spray dryer is 120 ℃, the outlet temperature is 60 ℃, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0031] (2) Li3PS4 powder is mixed with anhydrous ethanol, the mass ratio of Li3PS4 powder to anhydrous ethanol is 1:10, PEG-2000 is added, the amount of PEG-2000 is 0.5% of the total mass of Li3PS4 powder and anhydrous ethanol, and ultrasonic dispersion is performed for 40 min to obtain a suspension; LiH2PO4 ethanol solution is added dropwise to the suspension at a drop rate of 1 mL / min, the concentration of the LiH2PO4 ethanol solution is 0.2 mol / L, until the mass ratio of LiH2PO4 to Li3PS4 is 1:5, the pH is adjusted to 8.0 with ammonia water, stirring is performed at 40 ℃ and a stirring rate of 500 r / min for 3 h, to obtain a Li3PS4@Li3PO4 sol, the Li3PS4@Li3PO4 sol is formed into spherical particles by a spray dryer, then, under the atmosphere of inert gas, heating to 200 ℃ at a heating rate of 5 ℃ / min, calcining for 2 h, and after cooling, a second composite material is obtained; the inert gas is nitrogen, the inlet temperature of the spray dryer is 120 ℃, the outlet temperature is 60 ℃, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0032] (3) Li2S powder is mixed with anhydrous ethanol, the mass ratio of Li2S powder to anhydrous ethanol is 1:20, tetrabutyl titanate is added, the amount of tetrabutyl titanate is 0.3% of the total mass of Li2S powder and anhydrous ethanol, and ultrasonic dispersion is performed for 15 min to obtain a bridging slurry; (4) In an argon glove box, first, the first composite material obtained in step (1) is uniformly spread on one surface of the electrolyte film, then the bridging slurry obtained in step (3) is sprayed to form a wet film, and then the second composite material obtained in step (2) is uniformly spread on the wet film to obtain a composite solid-state electrolyte embryo; the composite solid-state electrolyte embryo is placed in a tube furnace, heated to 100℃ under an inert gas atmosphere, and kept for 1h to remove the solvent, and then heated to 250℃ and kept for 2h, and after natural cooling, Li2S reacts with Li3PO4 to form a Li3PO4-Li2S solid solution, and Li2S reacts with LiBH4 to form a Li2S-B2S3 bonding phase, realizing seamless connection of the interfaces, to obtain a composite solid-state electrolyte; the electrolyte film is a LPSC film modified by UDSH, the water and oxygen content of the argon glove box is ≤0.1ppm, and the thickness of the wet film is 10μm.

[0033] (5) A negative electrode sheet is prepared, and the negative electrode sheet is a lithium metal sheet.

[0034] (6) A positive electrode sheet is prepared, and lithium nickel cobalt manganese oxide coated with LiNbO3 on the surface is used as a positive electrode active material, the content of LiNbO3 is 1wt%, Li6PS5C is used as a positive electrode solid-state electrolyte, a nanometer carbon tube is used as a positive electrode conductive agent, PAA is used as a positive electrode binder, and p-xylene is used as a positive electrode solvent, the positive electrode active material, the positive electrode solid-state electrolyte, the positive electrode conductive agent, and the positive electrode binder are uniformly mixed in a mass ratio of 80:18:1:2, and then the positive electrode solvent is added to obtain a positive electrode slurry, and the positive electrode slurry is coated on the positive and negative sides of an aluminum foil, and then rolled, dried, and cut to obtain a positive electrode sheet.

[0035] (7) The positive electrode sheet, the composite solid-state electrolyte, and the negative electrode sheet are stacked in order to obtain a battery cell, the composite solid-state electrolyte is prepared by the preparation method of the composite electrolyte, and the negative electrode sheet is attached to the other surface of the electrolyte film, the battery cell is first densified at room temperature under a pressure of 10MPa for 5min, and then densified at 80℃ under a pressure of 50MPa for 20min to obtain a solid-state battery.

[0036] Example 3 (1) LiOH H2O and H3BO3 are dissolved in deionized water, the molar ratio of LiOH H2O to H3BO3 is 2:1, and a thickening agent is added, and the amount of the thickening agent is 1wt% of LiOH H2O and H3BO3 total mass of 1%, followed by 80 ℃, backflow reaction, stirring rate of 300 r / min, reaction time 2 h, after cooling, ultrasonic dispersion 20 min, Li2O-B2O3 sol is obtained; 0.1 mol / L LiBH4 solution is added to Li2O-B2O3 sol, the mass ratio of LiBH4 to Li2O-B2O3 is 1:4, under the atmosphere of inert gas, stirring for 1 h, adding anhydrous ether dropwise until particles are precipitated, then forming spherical particles by spray dryer, then, under the atmosphere of inert gas, heating to 200 ℃ at a heating rate of 5 ℃ / min, calcining for 2 h, then naturally cooling to 150 ℃, annealing for 1.5 h, to obtain the first composite material; the thickening agent is gum arabic, the inert gas is nitrogen or argon, the inlet temperature of the spray dryer is 120 ℃, the outlet temperature is 60 ℃, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0037] (2) Li3PS4 powder is mixed with anhydrous ethanol, the mass ratio of Li3PS4 powder to anhydrous ethanol is 1:10, PEG-2000 is added, the amount of PEG-2000 is 0.5% of the total mass of Li3PS4 powder and anhydrous ethanol, and ultrasonic dispersion is performed for 50 min to obtain a suspension; LiH2PO4 ethanol solution is added dropwise to the suspension at a drop rate of 1 mL / min, the concentration of the LiH2PO4 ethanol solution is 0.2 mol / L, until the mass ratio of LiH2PO4 to Li3PS4 is 1:5, the pH is adjusted to 7.9 with ammonia water, stirring is performed at 40 ℃ and a stirring rate of 500 r / min for 5 h to obtain a Li3PS4@Li3PO4 sol, the Li3PS4@Li3PO4 sol is formed into spherical particles by a spray dryer, then, under the atmosphere of inert gas, heating to 200 ℃ at a heating rate of 5 ℃ / min, calcining for 2 h, and after cooling, a second composite material is obtained; the inert gas is argon, the inlet temperature of the spray dryer is 120 ℃, the outlet temperature is 60 ℃, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0038] (3) Li2S powder is mixed with anhydrous ethanol, the mass ratio of Li2S powder to anhydrous ethanol is 1:20, tetrabutyl titanate is added, the amount of tetrabutyl titanate is 0.3% of the total mass of Li2S powder and anhydrous ethanol, and ultrasonic dispersion is performed for 15 min to obtain a bridging slurry; (4) In an argon glove box, first, the first composite material obtained in step (1) is uniformly spread on one surface of the electrolyte film, then the bridging slurry obtained in step (3) is sprayed to form a wet film, and then the second composite material obtained in step (2) is uniformly spread on the wet film to obtain a composite solid-state electrolyte embryo; the composite solid-state electrolyte embryo is placed in a tube furnace, heated to 100℃ under an inert gas atmosphere, and kept for 1h to remove the solvent, and then heated to 250℃ and kept for 2h, and after natural cooling, Li2S reacts with Li3PO4 to form a Li3PO4-Li2S solid solution, and Li2S reacts with LiBH4 to form a Li2S-B2S3 bonding phase, realizing seamless connection of the interfaces, to obtain a composite solid-state electrolyte; the electrolyte film is a LPSC film modified by UDSH, the water and oxygen content of the argon glove box is ≤0.1ppm, and the thickness of the wet film is 10μm.

[0039] (5) A negative electrode sheet is prepared, and the negative electrode sheet is a lithium metal sheet.

[0040] (6) A positive electrode sheet is prepared, and lithium nickel cobalt manganese oxide coated with LiNbO3 on the surface is used as a positive electrode active material, the content of LiNbO3 is 1wt%, Li6PS5C is used as a positive electrode solid-state electrolyte, a nanometer carbon tube is used as a positive electrode conductive agent, PAA is used as a positive electrode binder, and p-xylene is used as a positive electrode solvent, the positive electrode active material, the positive electrode solid-state electrolyte, the positive electrode conductive agent, and the positive electrode binder are uniformly mixed in a mass ratio of 80:18:1:2, then the positive electrode solvent is added to obtain a positive electrode slurry, and the positive electrode slurry is coated on the positive and negative sides of an aluminum foil, and then rolled, dried, and cut to obtain a positive electrode sheet.

[0041] (7) The positive electrode sheet, the composite solid-state electrolyte, and the negative electrode sheet are stacked in order to obtain a battery cell, the composite solid-state electrolyte is prepared by the preparation method of the composite electrolyte, the negative electrode sheet is attached to the other surface of the electrolyte film, the battery cell is first densified at room temperature under a pressure of 10MPa for 5min, and then densified at 80℃ under a pressure of 50MPa for 20min to obtain a solid-state battery.

[0042] Example 4 (1) LiOH H2O and H3BO3 are dissolved in deionized water, the molar ratio of LiOH H2O to H3BO3 is 2:1, and a thickening agent is added, and the amount of the thickening agent is 1wt% of LiOH H2O and H3BO3 total mass of 1%, followed by 80 ℃, backflow reaction, stirring rate of 300 r / min, reaction time 2 h, after cooling, ultrasonic dispersion 20 min, Li2O-B2O3 sol is obtained; 0.1 mol / L LiBH4 solution is added to Li2O-B2O3 sol, the mass ratio of LiBH4 to Li2O-B2O3 is 1:4, under the atmosphere of inert gas, stirring for 1 h, adding anhydrous ether dropwise until particles are precipitated, then forming spherical particles by spray dryer, then, under the atmosphere of inert gas, heating to 200 ℃ at a heating rate of 5 ℃ / min, calcining for 2 h, then naturally cooling to 150 ℃, annealing for 2 h, to obtain the first composite material; the thickening agent is gum arabic, the inert gas is argon, the inlet temperature of the spray dryer is 120 ℃, the outlet temperature is 60 ℃, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0043] (2) Li3PS4 powder is mixed with anhydrous ethanol, the mass ratio of Li3PS4 powder to anhydrous ethanol is 1:10, PEG-2000 is added, the amount of PEG-2000 is 0.5% of the total mass of Li3PS4 powder and anhydrous ethanol, and ultrasonic dispersion is performed for 60 min to obtain a suspension; LiH2PO4 ethanol solution is added dropwise to the suspension at a drop rate of 1 mL / min, the concentration of the LiH2PO4 ethanol solution is 0.2 mol / L, until the mass ratio of LiH2PO4 to Li3PS4 is 1:5, the pH is adjusted to 7.8 with ammonia water, stirring is performed at 40 ℃ and a stirring rate of 500 r / min for 2-5 h to obtain a Li3PS4@Li3PO4 sol, the Li3PS4@Li3PO4 sol is formed into spherical particles by a spray dryer, then, under the atmosphere of inert gas, heating to 200 ℃ at a heating rate of 5 ℃ / min, calcining for 2 h, and after cooling, a second composite material is obtained; the inert gas is nitrogen or argon, the inlet temperature of the spray dryer is 120 ℃, the outlet temperature is 60 ℃, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0044] (3) Li2S powder is mixed with anhydrous ethanol, the mass ratio of Li2S powder to anhydrous ethanol is 1:20, tetrabutyl titanate is added, the amount of tetrabutyl titanate is 0.3% of the total mass of Li2S powder and anhydrous ethanol, and ultrasonic dispersion is performed for 15 min to obtain a bridging slurry; (4) In an argon glove box, first, the first composite material obtained in step (1) is uniformly spread on one surface of the electrolyte film, then the bridging slurry obtained in step (3) is sprayed to form a wet film, and then the second composite material obtained in step (2) is uniformly spread on the wet film to obtain a composite solid-state electrolyte embryo; the composite solid-state electrolyte embryo is placed in a tube furnace, heated to 100℃ under an inert gas atmosphere, and kept for 1h to remove the solvent, and then heated to 250℃ and kept for 2h, and after natural cooling, Li2S reacts with Li3PO4 to form a Li3PO4-Li2S solid solution, and Li2S reacts with LiBH4 to form a Li2S-B2S3 bonding phase, realizing seamless connection of the interfaces, to obtain a composite solid-state electrolyte; the electrolyte film is a LPSC film modified by UDSH, the water and oxygen content of the argon glove box is ≤0.1ppm, and the thickness of the wet film is 10μm.

[0045] (5) A negative electrode sheet is prepared, and the negative electrode sheet is a lithium metal sheet.

[0046] (6) A positive electrode sheet is prepared, and lithium nickel cobalt manganese oxide coated with LiNbO3 on the surface is used as a positive electrode active material, the content of LiNbO3 is 1wt%, Li6PS5C is used as a positive electrode solid-state electrolyte, a nanometer carbon tube is used as a positive electrode conductive agent, PAA is used as a positive electrode binder, and p-xylene is used as a positive electrode solvent, the positive electrode active material, the positive electrode solid-state electrolyte, the positive electrode conductive agent, and the positive electrode binder are uniformly mixed in a mass ratio of 80:18:1:2, then the positive electrode solvent is added to obtain a positive electrode slurry, and the positive electrode slurry is coated on the positive and negative sides of an aluminum foil, and then rolled, dried, and cut to obtain a positive electrode sheet.

[0047] (7) The positive electrode sheet, the composite solid-state electrolyte, and the negative electrode sheet are stacked in order to obtain a battery cell, the composite solid-state electrolyte is prepared by the preparation method of the composite electrolyte, and the negative electrode sheet is attached to the other surface of the electrolyte film, the battery cell is first densified at room temperature under a pressure of 10MPa for 5min, and then densified at 80℃ under a pressure of 50MPa for 20min to obtain a solid-state battery.

[0048] Example 5 (1) LiOH H2O and H3BO3 are dissolved in deionized water, the molar ratio of LiOH H2O to H3BO3 is 2:1, and a thickening agent is added, and the amount of the thickening agent is 1wt% of LiOH H2O and H3BO3 total mass of 1%, followed by 80 ℃, backflow reaction, stirring rate of 300 r / min, reaction time 2 h, after cooling, ultrasonic dispersion 20 min, Li2O-B2O3 sol is obtained; to Li2O-B2O3 sol is added 0.1 mol / L LiBH4 solution, LiBH4 and Li2O-B2O3 mass ratio is 1:4, in the atmosphere of inert gas, stirring 1 h, dropwise addition of anhydrous ether until there are particles precipitate, and then by spray dryer to form spherical particles, followed by, in the atmosphere of inert gas, to 200 ℃ at a heating rate of 5 ℃ / min, calcination 2 h, and then natural cooling to 150 ℃, annealing 1.2 h, to obtain the first composite material; the thickening agent is gum arabic, the inert gas is argon, the inlet temperature of the spray dryer is 120 ℃, the outlet temperature is 60 ℃, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0049] (2) Li3PS4 powder and anhydrous ethanol are mixed, the mass ratio of Li3PS4 powder to anhydrous ethanol is 1:10, PEG-2000 is added, the amount of PEG-2000 is 0.5% of the total mass of Li3PS4 powder and anhydrous ethanol, and ultrasonic dispersion is performed for 60 min to obtain a suspension; dropwise addition of LiH2PO4 ethanol solution is performed to the suspension, the dropwise addition rate is 1 mL / min, the concentration of LiH2PO4 ethanol solution is 0.2 mol / L, until the mass ratio of LiH2PO4 to Li3PS4 is 1:5, ammonia water is used to adjust the pH to 7.7, stirring is performed at 40 ℃ and a stirring rate of 500 r / min for 4.5 h to obtain a Li3PS4@Li3PO4 sol, the Li3PS4@Li3PO4 sol is formed into spherical particles by a spray dryer, then, in the atmosphere of inert gas, heating to 200 ℃ at a heating rate of 5 ℃ / min, calcination 2 h, and after cooling, a second composite material is obtained; the inert gas is argon, the inlet temperature of the spray dryer is 120 ℃, the outlet temperature is 60 ℃, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0050] (3) Li2S powder and anhydrous ethanol are mixed, the mass ratio of Li2S powder to anhydrous ethanol is 1:20, tetrabutyl titanate is added, the amount of tetrabutyl titanate is 0.3% of the total mass of Li2S powder and anhydrous ethanol, and ultrasonic dispersion is performed for 15 min to obtain a bridging slurry; (4) In an argon glove box, first, the first composite material obtained in step (1) is uniformly spread on one surface of the electrolyte film, then the bridging slurry obtained in step (3) is sprayed to form a wet film, and then the second composite material obtained in step (2) is uniformly spread on the wet film to obtain a composite solid-state electrolyte embryo; the composite solid-state electrolyte embryo is placed in a tube furnace, heated to 100℃ under an inert gas atmosphere, and kept for 1h to remove the solvent, and then heated to 250℃ and kept for 2h, and after natural cooling, Li2S reacts with Li3PO4 to form a Li3PO4-Li2S solid solution, and Li2S reacts with LiBH4 to form a Li2S-B2S3 bonding phase, realizing seamless connection of the interfaces, to obtain a composite solid-state electrolyte; the electrolyte film is a LPSC film modified by UDSH, the water and oxygen content of the argon glove box is ≤0.1ppm, and the thickness of the wet film is 10μm.

[0051] (5) A negative electrode sheet is prepared, and the negative electrode sheet is a lithium metal sheet.

[0052] (6) A positive electrode sheet is prepared, and lithium nickel cobalt manganese oxide coated with LiNbO3 on the surface is used as a positive electrode active material, the content of LiNbO3 is 1wt%, Li6PS5C is used as a positive electrode solid-state electrolyte, a nanometer carbon tube is used as a positive electrode conductive agent, PAA is used as a positive electrode binder, and p-xylene is used as a positive electrode solvent, the positive electrode active material, the positive electrode solid-state electrolyte, the positive electrode conductive agent, and the positive electrode binder are uniformly mixed in a mass ratio of 80:18:1:2, then the positive electrode solvent is added to obtain a positive electrode slurry, and the positive electrode slurry is coated on the positive and negative sides of an aluminum foil, and then rolled, dried, and cut to obtain a positive electrode sheet.

[0053] (7) The positive electrode sheet, the composite solid-state electrolyte, and the negative electrode sheet are stacked in order to obtain a battery cell, the composite solid-state electrolyte is prepared by the preparation method of the composite electrolyte, and the negative electrode sheet is attached to the other surface of the electrolyte film, the battery cell is first densified at room temperature under a pressure of 10MPa for 5min, and then densified at 80℃ under a pressure of 50MPa for 20min to obtain a solid-state battery.

[0054] Example 6 (1) LiOH H2O and H3BO3 are dissolved in deionized water, the molar ratio of LiOH H2O to H3BO3 is 2:1, and a thickening agent is added, and the amount of the thickening agent is 1wt% of LiOH H2O and H3BO3 total mass of 1%, followed by 80 ℃, backflow reaction, stirring rate of 300 r / min, reaction time 2 h, after cooling, ultrasonic dispersion 20 min, Li2O-B2O3 sol is obtained; to Li2O-B2O3 sol is added 0.1 mol / L LiBH4 solution, LiBH4 and Li2O-B2O3 mass ratio is 1:4, in the atmosphere of inert gas, stirring 1 h, dropwise addition of anhydrous ether until there are particles precipitate, again by spray dryer to form spherical particles, then, in the atmosphere of inert gas, with the heating rate of 5 ℃ / min, heated to 200 ℃, calcined 2 h, again natural cooling to 150 ℃, annealing 1.3 h, the first composite material is obtained; the thickening agent is gum arabic, the inert gas is nitrogen or argon, the inlet temperature of the spray dryer is 120 ℃, the outlet temperature is 60 ℃, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0055] (2) Li3PS4 powder and anhydrous ethanol are mixed, the mass ratio of Li3PS4 powder to anhydrous ethanol is 1:10, PEG-2000 is added, the amount of PEG-2000 is 0.5% of the total mass of Li3PS4 powder and anhydrous ethanol, and ultrasonic dispersion is performed for 60 min to obtain a suspension; dropwise addition of LiH2PO4 ethanol solution is performed to the suspension, the dropwise addition rate is 1 mL / min, the concentration of LiH2PO4 ethanol solution is 0.2 mol / L, until the mass ratio of LiH2PO4 to Li3PS4 is 1:5, the pH is adjusted to 8.0 with ammonia water, stirring is performed at 40 ℃ with a stirring rate of 500 r / min for 2-5 h, and a Li3PS4@Li3PO4 sol is obtained. The Li3PS4@Li3PO4 sol is formed into spherical particles by a spray dryer, then, in the atmosphere of inert gas, with the heating rate of 5 ℃ / min, heated to 200 ℃, calcined 2 h, after cooling, the second composite material is obtained; the inert gas is nitrogen or argon, the inlet temperature of the spray dryer is 120 ℃, the outlet temperature is 60 ℃, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0056] (3) Li2S powder and anhydrous ethanol are mixed, the mass ratio of Li2S powder to anhydrous ethanol is 1:20, tetrabutyl titanate is added, the amount of tetrabutyl titanate is 0.3% of the total mass of Li2S powder and anhydrous ethanol, and ultrasonic dispersion is performed for 15 min to obtain a bridging slurry; (4) In an argon glove box, first, the first composite material obtained in step (1) is uniformly spread on one surface of the electrolyte film, then the bridging slurry obtained in step (3) is sprayed to form a wet film, and then the second composite material obtained in step (2) is uniformly spread on the wet film to obtain a composite solid-state electrolyte embryo; the composite solid-state electrolyte embryo is placed in a tube furnace, heated to 100℃ under an inert gas atmosphere, and kept for 1h to remove the solvent, and then heated to 250℃ and kept for 2h, and after natural cooling, Li2S reacts with Li3PO4 to form a Li3PO4-Li2S solid solution, and Li2S reacts with LiBH4 to form a Li2S-B2S3 bonding phase, realizing seamless connection of the interfaces, to obtain a composite solid-state electrolyte; the electrolyte film is a LPSC film modified by UDSH, the water and oxygen content of the argon glove box is ≤0.1ppm, and the thickness of the wet film is 10μm.

[0057] (5) A negative electrode sheet is prepared, and the negative electrode sheet is a lithium metal sheet.

[0058] (6) A positive electrode sheet is prepared, and lithium nickel cobalt manganese oxide coated with LiNbO3 on the surface is used as a positive electrode active material, the content of LiNbO3 is 1wt%, Li6PS5C is used as a positive electrode solid-state electrolyte, a nanometer carbon tube is used as a positive electrode conductive agent, PAA is used as a positive electrode binder, and p-xylene is used as a positive electrode solvent, the positive electrode active material, the positive electrode solid-state electrolyte, the positive electrode conductive agent, and the positive electrode binder are uniformly mixed in a mass ratio of 80:18:1:2, and then the positive electrode solvent is added to obtain a positive electrode slurry, and the positive electrode slurry is coated on the positive and negative sides of an aluminum foil, and then rolled, dried, and cut to obtain a positive electrode sheet.

[0059] (7) The positive electrode sheet, the composite solid-state electrolyte, and the negative electrode sheet are stacked in order to obtain a battery cell, the composite solid-state electrolyte is prepared by the preparation method of the composite electrolyte, and the negative electrode sheet is attached to the other surface of the electrolyte film, the battery cell is first densified at room temperature under a pressure of 10MPa for 5min, and then densified at 80℃ under a pressure of 50MPa for 20min to obtain a solid-state battery.

[0060] Comparative Example 1 (1) LiOH H2O and H3BO3 are dissolved in deionized water, the molar ratio of LiOH H2O to H3BO3 is 2:1, and a thickening agent is added, and the amount of the thickening agent is 10wt% of LiOH H2O and H3BO3 total mass of 1%, followed by 80℃, backflow reaction, stirring rate of 300r / min, reaction time 2h, after cooling, ultrasonic dispersion 20min, Li2O-B2O3 sol is obtained; 0.1mol / L LiBH4 solution is added to Li2O-B2O3 sol, the mass ratio of LiBH4 and Li2O-B2O3 is 1:4, under the atmosphere of inert gas, stirring 1h, anhydrous ether is added dropwise until the particles are precipitated, then the spherical particles are formed by spray dryer, then, under the atmosphere of inert gas, the temperature is raised to 200℃ at a heating rate of 5℃ / min, calcined for 2h, then naturally cooled to 150℃, annealed for 1h, to obtain the first composite material; the thickening agent is gum arabic, the inert gas is nitrogen, the inlet temperature of the spray dryer is 120℃, the outlet temperature is 60℃, the pressure is 0.3MPa, and the feeding rate is 5mL / min.

[0061] (2) Li3PS4 powder is mixed with anhydrous ethanol, the mass ratio of Li3PS4 powder to anhydrous ethanol is 1:10, PEG-2000 is added, the amount of PEG-2000 is 0.5% of the total mass of Li3PS4 powder and anhydrous ethanol, ultrasonic dispersion is carried out for 30min to obtain a suspension; LiH2PO4 ethanol solution is added dropwise to the suspension, the dropwise speed is 1mL / min, the concentration of LiH2PO4 ethanol solution is 0.2mol / L, until the mass ratio of LiH2PO4 to Li3PS4 is 1:5, the pH is adjusted to 7.5 with ammonia water, stirring is carried out at 40℃ with a stirring rate of 500r / min for 2h to obtain Li3PS4@Li3PO4 sol, the Li3PS4@Li3PO4 sol is formed into spherical particles by spray dryer, then, under the atmosphere of inert gas, the temperature is raised to 200℃ at a heating rate of 5℃ / min, calcined for 2h, after cooling, the second composite material is obtained; the inert gas is argon, the inlet temperature of the spray dryer is 120℃, the outlet temperature is 60℃, the pressure is 0.3MPa, and the feeding rate is 5mL / min.

[0062] (3) The first composite material obtained in step (1) is uniformly spread on one surface of the electrolyte membrane, then the second composite material obtained in step (2) is uniformly spread on the aforementioned first composite material to obtain a composite solid-state electrolyte; the electrolyte membrane is a LPSC membrane modified by UDSH.

[0063] (4) A negative electrode sheet is prepared, which is a lithium metal sheet.

[0064] (5) Preparing a positive electrode sheet, using LiNbO3-coated nickel cobalt lithium manganate as a positive electrode active material, the content of LiNbO3 being 1 wt%, using Li6PS5C as a positive electrode solid electrolyte, using a nanometer carbon tube as a positive electrode conductive agent, using PAA as a positive electrode binder, using p-xylene as a positive electrode solvent, mixing the positive electrode active material, the positive electrode solid electrolyte, the positive electrode conductive agent, and the positive electrode binder uniformly in a mass ratio of 80:18:1:2, adding the positive electrode solvent to obtain a positive electrode slurry, and coating the positive electrode slurry on the positive and negative sides of an aluminum foil, rolling, drying, and cutting to obtain the positive electrode sheet.

[0065] (6) Stacking in the order of the positive electrode sheet, the composite solid electrolyte, and the negative electrode sheet to obtain a battery cell, the composite solid electrolyte being prepared by the preparation method of the composite electrolyte, and the negative electrode sheet being attached to the other surface of the electrolyte film, first performing pressure densification on the battery cell at room temperature, the pressure being 10 MPa and the pressure holding time being 5 min, and then performing pressure densification on the battery cell at 80°C, the pressure being 50 MPa and the pressure holding time being 20 min, to obtain a solid-state battery.

[0066] Comparative Example 2 (1) Mixing Li3PS4 powder and anhydrous ethanol, the mass ratio of Li3PS4 powder to anhydrous ethanol being 1:10, adding PEG-2000, the amount of PEG-2000 being 0.5% of the total mass of Li3PS4 powder and anhydrous ethanol, and ultrasonic dispersion for 30 min to obtain a suspension; adding an ethanol solution of LiH2PO4 dropwise into the suspension, the drop rate being 1 mL / min, the concentration of the ethanol solution of LiH2PO4 being 0.2 mol / L, until the mass ratio of LiH2PO4 to Li3PS4 is 1:5, adjusting the pH to 7.5 with ammonia water, stirring at 500 r / min at 40°C for 2 h to obtain a Li3PS4@Li3PO4 sol, forming the Li3PS4@Li3PO4 sol into spherical particles through a spray dryer, and then heating to 200°C at a heating rate of 5°C / min in an atmosphere of an inert gas, calcining for 2 h, and cooling to obtain a second composite material; the inert gas is argon, the inlet temperature of the spray dryer is 120°C, the outlet temperature is 60°C, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0067] (2) First, spreading the second composite material obtained in step (1) uniformly on one surface of an electrolyte film to obtain a composite solid electrolyte; the electrolyte film is a UDSH-modified LPSC film.

[0068] (3) Preparing a negative electrode sheet, the negative electrode sheet being a lithium metal sheet.

[0069] (4) Preparing a positive electrode sheet, using LiNbO3-coated nickel cobalt lithium manganate as a positive electrode active material, the content of LiNbO3 being 1 wt%, using Li6PS5C as a positive electrode solid electrolyte, using a nanometer carbon tube as a positive electrode conductive agent, using PAA as a positive electrode binder, using p-xylene as a positive electrode solvent, mixing the positive electrode active material, the positive electrode solid electrolyte, the positive electrode conductive agent, and the positive electrode binder uniformly in a mass ratio of 80:18:1:2, adding the positive electrode solvent to obtain a positive electrode slurry, and coating the positive electrode slurry on the positive and negative sides of an aluminum foil, rolling, drying, and cutting to obtain the positive electrode sheet.

[0070] (5) Stacking in the order of the positive electrode sheet, the composite solid electrolyte, and the negative electrode sheet to obtain a battery cell, the negative electrode sheet being attached to the other surface of the electrolyte film, first performing pressure densification on the battery cell at room temperature, the pressure being 10 MPa, and the pressure holding time being 5 min, then performing pressure densification on the battery cell at 80℃, the pressure being 50 MPa, and the pressure holding time being 20 min, to obtain a solid-state battery.

[0071] Comparative Example 3 (1) Dissolving LiOH H2O and H3BO3 in deionized water, the molar ratio of LiOH H2O to H3BO3 being 2:1, adding a thickening agent, the amount of the thickening agent being 1% of the total mass of LiOH H2O and H3BO3, then performing a reflux reaction at 80℃, the stirring rate being 300 r / min, the reaction time being 2 h, after cooling, ultrasonic dispersion being performed for 20 min, to obtain a Li2O-B2O3 sol; adding a 0.1 mol / L LiBH4 solution to the Li2O-B2O3 sol, the mass ratio of LiBH4 to Li2O-B2O3 being 1:4, stirring for 1 h in an inert gas atmosphere, adding anhydrous ether dropwise until particles are precipitated, forming spherical particles through a spray dryer, then heating to 200℃ at a heating rate of 5℃ / min in an inert gas atmosphere, calcining for 2 h, and then naturally cooling to 150℃ and annealing for 1 h to obtain a first composite material; the thickening agent is gum arabic, the inert gas is nitrogen, the inlet temperature of the spray dryer is 120℃, the outlet temperature is 60℃, the pressure is 0.3 MPa, and the feeding rate is 5 mL / min.

[0072] (2) In an argon glove box, first spreading the first composite material obtained in step (1) on one surface of an electrolyte film to obtain a composite solid electrolyte; the electrolyte film is a UDSH-modified LPSC film.

[0073] (3) Preparing a negative electrode sheet, the negative electrode sheet being a lithium metal sheet.

[0074] (4) The positive electrode sheet is prepared by using LiNbO3-coated lithium nickel cobalt manganese oxide as the positive electrode active material, the content of LiNbO3 being 1 wt%, Li6PS5C as the positive electrode solid electrolyte, nanometer carbon tube as the positive electrode conductive agent, PAA as the positive electrode binder, and p-xylene as the positive electrode solvent. The positive electrode active material, the positive electrode solid electrolyte, the positive electrode conductive agent, and the positive electrode binder are mixed uniformly at a mass ratio of 80:18:1:2, and then the positive electrode solvent is added to obtain a positive electrode slurry. The positive electrode slurry is coated on the positive and negative sides of an aluminum foil, and then rolled, dried, and cut to obtain the positive electrode sheet.

[0075] (5) The positive electrode sheet, the composite solid electrolyte, and the negative electrode sheet are laminated in sequence to obtain a battery cell. The negative electrode sheet is attached to the other surface of the electrolyte film. The battery cell is first densified at room temperature under a pressure of 10 MPa for 5 min, and then densified at 80°C under a pressure of 50 MPa for 20 min to obtain a solid-state battery.

[0076] Comparative Example 4 (1) The negative electrode sheet is prepared by using a lithium metal sheet.

[0077] (2) The positive electrode sheet is prepared by using LiNbO3-coated lithium nickel cobalt manganese oxide as the positive electrode active material, the content of LiNbO3 being 1 wt%, Li6PS5C as the positive electrode solid electrolyte, nanometer carbon tube as the positive electrode conductive agent, PAA as the positive electrode binder, and p-xylene as the positive electrode solvent. The positive electrode active material, the positive electrode solid electrolyte, the positive electrode conductive agent, and the positive electrode binder are mixed uniformly at a mass ratio of 80:18:1:2, and then the positive electrode solvent is added to obtain a positive electrode slurry. The positive electrode slurry is coated on the positive and negative sides of an aluminum foil, and then rolled, dried, and cut to obtain the positive electrode sheet.

[0078] (3) The positive electrode sheet, the electrolyte film, and the negative electrode sheet are laminated in sequence to obtain a battery cell. The electrolyte film is a UDSH-modified LPSC film. The battery cell is first densified at room temperature under a pressure of 10 MPa for 5 min, and then densified at 80°C under a pressure of 50 MPa for 20 min to obtain a solid-state battery.

[0079] The performance of the above multiple examples and comparative examples is tested, and the test results are shown in Table 1.

[0080] Table 1 The data are analyzed, and example 1 is compared with comparative examples 1-4, which are different in that comparative example 1 does not use a bridging layer design, comparative example 2 only has a second composite material, comparative example 3 only has a first composite material, and comparative example 4 does not use a composite solid-state electrolyte; the use of a composite solid-state electrolyte can reduce the interfacial impedance and improve the cycle performance, comparative example 1 has two composite layers, but lacks Li2S as a bridging layer, and cannot firmly connect the two composite layers, so that the composite solid-state electrolyte has multiple interfaces, thereby increasing the interfacial impedance, and is prone to falling off during subsequent charge and discharge processes, and has poor cycle performance, comparative example 2 only has a second composite material, which provides high conductivity while also having a very wide electrochemical stability window, can directly and stably contact the high-voltage positive electrode, effectively inhibits the release of positive active oxygen and interfacial side reactions, and effectively blocks the diffusion of transition metal ions such as Co, Mn, and Ni in the positive electrode to the electrolyte side, and the design of a single composite layer makes the composite layer and the electrolyte film more reliable than comparative example 1, so the interfacial impedance and cycle performance of comparative example 2 are slightly better than those of comparative example 1, the first composite material of comparative example 3 can reduce the interfacial impedance and reduce the problem of falling off during subsequent charge and discharge processes, but due to the limitations of the material, it does not have high conductivity and a wide electrochemical stability window, and it is difficult to directly and stably contact the high-voltage positive electrode, so in practical applications, the interfacial impedance and cycle performance are worse than those of comparative examples 1 and 2, and comparative example 4 does not use a composite solid-state electrolyte, but uses a traditional structure design, and cannot inhibit the occurrence of side reactions, so that the initial interfacial impedance is high, the interfacial impedance increases by more than twice after 100 cycles, resulting in poor cycle performance and low capacity retention rate.

[0081] The above is only a preferred embodiment of the present application, and does not limit the technical scope of the present application in any way, so any minor modification, equivalent change and modification of the above embodiment according to the technical essence of the present application still falls within the scope of the technical solution of the present application.

Claims

1. A method for preparing a composite electrolyte, characterized in that: It includes the following steps: (1) LiOH H₂O and H₃BO₃ dissolve in deionized water, LiOH The molar ratio of H2O to H3BO3 is 2:

1. A thickener is then added, with the amount of thickener being LiOH. 1% of the total mass of H2O and H3BO3 was added, and then refluxed at 80℃ with a stirring rate of 300 r / min for 2 h. After cooling, the mixture was ultrasonically dispersed for 20 min to obtain Li2O-B2O3 sol. 0.1 mol / L LiBH4 solution was added to the Li2O-B2O3 sol, with a mass ratio of LiBH4 to Li2O-B2O3 of 1:

4. The mixture was stirred for 1 h in an inert gas atmosphere, and anhydrous diethyl ether was added dropwise until particles precipitated. The particles were then dried using a spray dryer to form spherical particles. Subsequently, the mixture was heated to 200℃ at a heating rate of 5℃ / min in an inert gas atmosphere and calcined for 2 h. Then, it was naturally cooled to 150℃ and annealed for 1-2 h to obtain the first composite material. (2) Mix Li3PS4 powder with anhydrous ethanol at a mass ratio of 1:

10. Add PEG-2000 at a concentration of 0.5% of the total mass of Li3PS4 powder and anhydrous ethanol. Disperse the mixture ultrasonically for 30-60 min to obtain a suspension. Add an ethanol solution of LiH2PO4 dropwise to the suspension at a rate of 1 mL / min. The concentration of the ethanol solution of LiH2PO4 is 0.2 mol / L. Continue adding the solution until Li... The mass ratio of H2PO4 to Li3PS4 is 1:

5. The pH is adjusted to 7.5-8.0 with ammonia. The mixture is stirred at 40℃ and a stirring rate of 500 r / min for 2-5 h to obtain Li3PS4@Li3PO4 sol. The Li3PS4@Li3PO4 sol is then spray-dried to form spherical particles. Subsequently, under an inert gas atmosphere, the temperature is raised to 200℃ at a heating rate of 5℃ / min and calcined for 2 h. After cooling, the second composite material is obtained. (3) Mix Li2S powder with anhydrous ethanol at a mass ratio of 1:20, add tetrabutyl titanate at a mass ratio of 0.3% of the total mass of Li2S powder and anhydrous ethanol, and ultrasonically disperse for 15 min to obtain bridging slurry. (4) In an argon glove box, the first composite material obtained in step (1) is first evenly spread on one surface of the electrolyte membrane, and then the bridging slurry obtained in step (3) is sprayed to form a wet film. Then, the second composite material obtained in step (2) is evenly spread on the aforementioned wet film to obtain a composite solid electrolyte preform. The composite solid electrolyte preform is placed in a tube furnace and heated to 100°C in an inert gas atmosphere. It is kept at this temperature for 1 hour to remove the solvent. Then, it is heated to 250°C and kept at this temperature for 2 hours. After natural cooling, Li2S reacts with Li3PO4 to form a Li3PO4-Li2S solid solution, and Li2S reacts with LiBH4 to form a Li2S-B2S3 combined phase, achieving seamless interface connection and obtaining a composite solid electrolyte.

2. The method for preparing the composite electrolyte according to claim 1, characterized in that: In step (1), the thickener is gum arabic.

3. The method for preparing the composite electrolyte according to claim 1, characterized in that: In step (1), the inert gas is nitrogen or argon.

4. The method for preparing the composite electrolyte according to claim 1, characterized in that: In step (2), the inert gas is nitrogen or argon.

5. The method for preparing the composite electrolyte according to claim 1, characterized in that: In step (4), the electrolyte membrane is an LPSC membrane modified with UDSH.

6. The method for preparing the composite electrolyte according to claim 1, characterized in that: In step (4), the oxygen content of the argon glove box is ≤0.1ppm.

7. The method for preparing the composite electrolyte according to claim 1, characterized in that: In steps (1) and (2), the inlet temperature of the spray dryer is 120°C, the outlet temperature is 60°C, the pressure is 0.3MPa, and the feed rate is 5mL / min.

8. The method for preparing the composite electrolyte according to claim 1, characterized in that: In step (4), the thickness of the wet film is 10 μm.

9. A method for preparing a solid-state battery, characterized in that: It includes the following steps: (a) Preparation of negative electrode sheet; (b) Preparation of the positive electrode sheet; (a) A cell is obtained by stacking a positive electrode, a composite solid electrolyte, and a negative electrode in that order. The composite solid electrolyte is prepared by the method of preparing the composite electrolyte according to any one of claims 1-8. The negative electrode is attached to the other surface of the electrolyte film. The cell is first densified under pressure at room temperature at a pressure of 10 MPa for a holding time of 5 min. Then, the cell is densified under pressure at 80°C at a pressure of 50 MPa for a holding time of 20 min to obtain a solid-state battery.

10. The method for preparing a solid-state battery according to claim 9, characterized in that: The preparation process of its positive electrode is as follows: Lithium nickel cobalt manganese oxide with a surface coating of LiNbO3 is used as the positive electrode active material, with a LiNbO3 content of 1wt%. Li6PS5C is used as the positive electrode solid electrolyte, carbon nanotubes are used as the positive electrode conductive agent, PAA is used as the positive electrode binder, and p-xylene is used as the positive electrode solvent. The positive electrode active material, positive electrode solid electrolyte, positive electrode conductive agent, and positive electrode binder are mixed evenly in a mass ratio of 80:18:1:2, and then the positive electrode solvent is added to obtain a positive electrode slurry. The positive electrode slurry is coated on both sides of an aluminum foil, and after rolling, drying, and cutting, a positive electrode sheet is obtained. The negative electrode sheet is a lithium metal sheet.

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