Sulfide solid electrolyte composite material and structural energy storage integrated lithium ion battery and preparation method thereof

Abstract

The invention belongs to the technical field of battery materials, and provides a sulfide solid electrolyte composite material, a structural energy storage integrated lithium ion battery and a preparation method thereof. The sulfide solid electrolyte composite material comprises an inner core and a coating layer, the surface of the inner core is coated with the coating layer, the inner core is a sulfide solid electrolyte, and the coating layer is an oxygen-containing lithium compound; the species of oxygen-containing lithium compounds are defined. The sulfide solid electrolyte is coated with at least two oxygen-containing lithium compounds, and the oxygen-containing lithium compounds are compatible with the sulfide solid electrolyte in the heat treatment process, so that the air stability and the oxidation resistance of the electrolyte are remarkably improved; a solution method coating and calcining process is adopted, so that a coating layer is uniformly dispersed, and the stability of the composite material is improved; the sulfide solid electrolyte composite material, a carbon fiber electrode and a glass fiber woven cloth diaphragm are assembled into the structural energy storage integrated lithium ion battery, the lithium ion battery has excellent specific capacity, cycling stability and rate capability, and the service life is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and in particular to a sulfide solid electrolyte composite material, a structural energy storage integrated lithium-ion battery, and a preparation method thereof. Background Art

[0002] In lithium-ion batteries, traditional organic liquid electrolytes have problems such as flammability and explosiveness, and it is difficult to meet the usage requirements of high safety and high energy density. Solid electrolytes have received extensive attention due to their advantages such as non-flammability and environmental friendliness. Sulfide solid electrolytes have high ionic conductivity, a wide electrochemical window, and good flexibility, and have broad application prospects in all-solid-state lithium-ion batteries, structural energy storage integrated devices, and other energy devices. Sulfide solid electrolytes are prone to moisture absorption and react with moisture in the air to generate toxic hydrogen sulfide gas, resulting in problems such as material decomposition, decreased ionic conductivity, and environmental pollution. When some sulfide solid electrolytes are combined with high-voltage electrode materials, there are interfacial side reactions, resulting in a decrease in the cycle stability of the battery. Therefore, how to improve the air stability, ionic conductivity, and electrochemical performance of sulfide solid electrolytes has become a challenge faced by current research and industrial applications.

[0003] Currently, the air stability of sulfide solid electrolytes is often improved by means such as element doping, surface coating, or local modification. For example, surface coating of sulfide solid electrolytes with oxygen-containing compounds (Li3PO4, Li2ZrO3, LiNO3, etc.) can block the contact between sulfides and the external environment to a certain extent, reduce moisture erosion, and improve the interfacial problems between the electrolyte and the electrode material. However, there are problems such as uneven distribution of the coating layer, easy decomposition under high-temperature conditions, and difficulty in large-scale production.

[0004] At the same time, structural energy storage integration has gradually become the development direction of the energy field. Carbon fiber woven cloth plays an important role in realizing structural energy storage integration due to its high specific strength and high specific modulus. Using carbon fiber woven cloth as the electrode substrate, replacing the traditional polymer separator with glass fiber woven cloth, and then combining with a highly stable sulfide solid electrolyte, it is expected to obtain a carbon fiber battery with structural energy storage integration.

[0005] Therefore, how to improve sulfide solid electrolytes to obtain sulfide solid electrolyte composite materials, and combine the technology of structural energy storage integration to obtain lithium-ion batteries with high ionic conductivity and excellent cycle stability is of great significance for the rapid development of the battery field. Summary of the Invention

[0006] The purpose of the present invention is to provide a sulfide solid electrolyte composite material, a structural energy storage integrated lithium-ion battery, and a preparation method thereof in view of the deficiencies of the prior art.

[0007] To achieve the above-mentioned invention objectives, the present invention provides the following technical solutions:

[0008] The present invention provides a sulfide solid electrolyte composite material, comprising a core and a coating layer, and the coating layer coats the surface of the core;

[0009] The core is a sulfide solid electrolyte, and the coating layer is an oxygen-containing lithium compound;

[0010] The oxygen-containing lithium compound comprises at least two of Li2AlO2, Li2TiO3, Li2ZrO3, Li3PO4, Li2SO4, Li2CO3 and Li2SiO3.

[0011] Preferably, the mass of the coating layer is 0.1-5% of the mass of the core.

[0012] Preferably, the sulfide solid electrolyte is Li (7-a) PS (6-a) X a , Li7P3S 11 , Li 10 GeP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , Li7GePS8 or Li4SnS4, where X is Cl, Br or I, and 0.5≤a≤1.75.

[0013] The present invention also provides a preparation method of the sulfide solid electrolyte composite material, comprising the following steps:

[0014] 1) Dispersing the sulfide solid electrolyte in an organic solvent to obtain a mixed solution A;

[0015] 2) Adding the oxygen-containing lithium compound to the mixed solution A to obtain a mixed solution B;

[0016] 3) Performing heat treatment on the mixed solution B to obtain an electrolyte precursor;

[0017] 4) Calcining the electrolyte precursor to obtain the sulfide solid electrolyte composite material.

[0018] Preferably, the organic solvent in step 1) comprises one or more of anhydrous ethanol, isopropanol, acetone, dimethyl sulfoxide and N,N-dimethylformamide;

[0019] The mass-volume ratio of the sulfide solid electrolyte to the organic solvent is 1 g: 10-15 mL.

[0020] Preferably, the temperature of the heat treatment in step 3) is 30-160 °C, and the time of the heat treatment is 0.5-24 h.

[0021] Preferably, the temperature of the calcination in step 4) is 150-650 °C, the time of the calcination is 0.5-24 h, and the heating rate for heating to the calcination temperature is 3-10 °C / min.

[0022] The present invention also provides a structural energy storage integrated lithium-ion battery. The electrode material of the structural energy storage integrated lithium-ion battery is a composite material based on a carbon fiber woven cloth, the separator is a glass fiber woven cloth, and the solid electrolyte is the sulfide solid electrolyte composite material described above.

[0023] Preferably, the surface density of the carbon fiber woven cloth ≤ 30 g / ㎡, and the diameter of the carbon fiber in the carbon fiber woven cloth ≤ 7 μm;

[0024] The unit area mass of the glass fiber woven cloth ≤ 15 g / ㎡, and the thickness of the glass fiber woven cloth ≤ 10 μm.

[0025] The present invention also provides a preparation method of the structural energy storage integrated lithium-ion battery described above, comprising the following steps:

[0026] 1) Coating the positive electrode slurry on the carbon fiber woven cloth to obtain a carbon fiber positive electrode; coating the negative electrode slurry on the carbon fiber woven cloth to obtain a carbon fiber negative electrode;

[0027] 2) Sequentially encapsulating the carbon fiber positive electrode, the solid electrolyte, the glass fiber woven cloth and the carbon fiber negative electrode to obtain the structural energy storage integrated lithium-ion battery;

[0028] The solid electrolyte is the sulfide solid electrolyte composite material described above.

[0029] The beneficial effects of the present invention include the following points:

[0030] 1) The present invention uses at least two oxygen-containing lithium compounds to coat and modify the sulfide solid electrolyte. The oxygen-containing lithium compound has low conductivity and thermal decomposition stability, can be compatible with the sulfide solid electrolyte during the heat treatment process, generate a more stable interfacial phase, and play a lithium supplementing role; a strong protective layer is formed by coating to isolate the intrusion of moisture in the external environment, significantly improving the air stability and antioxidant ability of the electrolyte, while increasing the ionic conductivity and broadening the electrochemical window; the solution coating and calcination process are adopted to enable the coating layer to be uniformly dispersed on the surface of the sulfide solid electrolyte, further improving the stability of the composite material and reducing side reactions; the sulfide solid electrolyte composite material of the present invention has an ionic conductivity ≥ 2 mS / cm at 25 °C, and after being exposed to air for 4 h, the attenuation rate of the ionic conductivity ≤ 12%.

[0031] 2) The sulfide solid electrolyte composite material of the present invention is assembled with a carbon fiber electrode and a glass fiber woven cloth diaphragm to form a structural energy storage integrated lithium-ion battery, which has excellent specific capacity, cycle stability and rate performance, extends the service life, and can obtain good specific capacity in the range of 0.2 to 1C at 25°C; at the same time, it has integrity and stability in harsh environments such as impact and vibration, can maintain stable energy storage under different load conditions, and can be widely applied to fields with high requirements for lightweight, strength and safety, such as aerospace, transportation, portable devices, etc., and the preparation process is simple and easy to industrialize. Detailed implementation mode

[0032] The present invention provides a sulfide solid electrolyte composite material, which includes a core and a coating layer, and the coating layer covers the surface of the core;

[0033] The core is a sulfide solid electrolyte, and the coating layer is an oxygen-containing lithium compound;

[0034] The oxygen-containing lithium compound includes at least two of Li2AlO2, Li2TiO3, Li2ZrO3, Li3PO4, Li2SO4, Li2CO3 and Li2SiO3.

[0035] In the present invention, the mass of the coating layer is preferably 0.1 to 5% of the mass of the core, more preferably 0.5 to 3%, and even more preferably 1 to 2%.

[0036] In the present invention, the sulfide solid electrolyte is preferably Li (7-a) PS (6-a) X a , Li7P3S 11 , Li 10 GeP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , Li7GePS8 or Li4SnS4, where X is preferably Cl, Br or I, and 0.5 ≤ a ≤ 1.75.

[0037] The present invention also provides a preparation method of the sulfide solid electrolyte composite material, which includes the following steps:

[0038] 1) Dispersing the sulfide solid electrolyte in an organic solvent to obtain a mixed solution A;

[0039] 2) Adding an oxygen-containing lithium compound to the mixed solution A to obtain a mixed solution B;

[0040] 3) Heat-treating the mixed solution B to obtain an electrolyte precursor;

[0041] 4) Calcinate the electrolyte precursor to obtain the sulfide solid electrolyte composite material.

[0042] In the present invention, the organic solvent described in step 1) preferably includes one or more of absolute ethanol, isopropanol, acetone, dimethyl sulfoxide, and N,N-dimethylformamide;

[0043] The mass-volume ratio of the sulfide solid electrolyte to the organic solvent is preferably 1 g: 10 - 15 mL, more preferably 1 g: 11 - 14 mL, and even more preferably 1 g: 12 - 13 mL. Selecting an organic solvent with moderate polarity can make the oxygen-containing lithium compound and the sulfide solid electrolyte mix as evenly as possible under stirring, which is beneficial to the formation of a stable electrolyte precursor.

[0044] In the present invention, step 1) is preferably carried out under an inert atmosphere, and the dispersion in step 1) is preferably carried out under stirring conditions;

[0045] After adding the oxygen-containing lithium compound in step 2), it is preferably stirred to obtain the mixed solution B.

[0046] In the present invention, the rotation speed of the stirring is preferably 80 - 800 r / min independently, more preferably 100 - 600 r / min, and even more preferably 200 - 400 r / min; the stirring time is preferably 10 - 180 min independently, more preferably 30 - 150 min, and even more preferably 60 - 90 min.

[0047] In the present invention, the temperature of the heat treatment in step 3) is preferably 30 - 160 °C, more preferably 50 - 120 °C, and even more preferably 60 - 80 °C; the heat treatment time is preferably 0.5 - 24 h, more preferably 1 - 16 h, and even more preferably 3 - 8 h. The function of the heat treatment is to volatilize the remaining organic solvent.

[0048] In the present invention, the temperature of the calcination in step 4) is preferably 150 - 650 °C, more preferably 300 - 600 °C, and even more preferably 450 - 550 °C; the calcination time is preferably 0.5 - 24 h, more preferably 5 - 16 h, and even more preferably 6 - 10 h; the heating rate to the calcination temperature is preferably 3 - 10 °C / min, more preferably 5 - 8 °C / min, and even more preferably 6 - 7 °C / min. Too high a calcination temperature may cause the decomposition of the sulfide solid electrolyte and the formation of impurity phases; too low a calcination temperature is difficult to form a tight bond between the coating layer and the sulfide solid electrolyte.

[0049] In the present invention, the electrolyte precursor in step 4) is preferably pre-calcined first and then calcined; the pre-calcination temperature is preferably 200 - 300 °C, more preferably 250 °C; the pre-calcination time is preferably 2 - 4 h, more preferably 3 h; the heating rate for heating to the pre-calcination temperature is preferably 3 - 10 °C / min, more preferably 5 - 8 °C / min, and even more preferably 6 - 7 °C / min.

[0050] The present invention also provides a structural energy storage integrated lithium-ion battery, wherein the electrode material of the structural energy storage integrated lithium-ion battery is a composite material based on a carbon fiber woven fabric, the separator is a glass fiber woven fabric, and the solid electrolyte is the sulfide solid electrolyte composite material described above.

[0051] In the present invention, using a carbon fiber woven fabric as the substrate of the electrode material has the characteristics of high strength and low weight, and while providing mechanical support and enhancement effects, it also has a conductive function; using a glass fiber woven fabric as the separator has good thermal stability and barrier properties, significantly improving the battery safety.

[0052] In the present invention, the surface density of the carbon fiber woven fabric is preferably ≤ 30 g / ㎡, more preferably ≤ 28 g / ㎡, and even more preferably ≤ 25 g / ㎡; the diameter of the carbon fiber in the carbon fiber woven fabric is preferably ≤ 7 μm, more preferably ≤ 6 μm, and even more preferably ≤ 5 μm;

[0053] The mass per unit area of the glass fiber woven fabric is preferably ≤ 15 g / ㎡, more preferably ≤ 12 g / ㎡, and even more preferably ≤ 10 g / ㎡; the thickness of the glass fiber woven fabric is preferably ≤ 10 μm, more preferably ≤ 9 μm, and even more preferably ≤ 8 μm.

[0054] The present invention also provides a preparation method of the structural energy storage integrated lithium-ion battery described above, comprising the following steps:

[0055] 1) Coating the positive electrode slurry on the carbon fiber woven fabric to obtain a carbon fiber positive electrode; coating the negative electrode slurry on the carbon fiber woven fabric to obtain a carbon fiber negative electrode;

[0056] 2) Sequentially encapsulating the carbon fiber positive electrode, the solid electrolyte, the glass fiber woven fabric, and the carbon fiber negative electrode to obtain the structural energy storage integrated lithium-ion battery;

[0057] The solid electrolyte is the sulfide solid electrolyte composite material described above.

[0058] The technical solutions provided by the present invention will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0059] Example 1

[0060] Under an argon atmosphere, 30 g of Li6PS5Cl solid electrolyte powder was added to 300 mL of absolute ethanol and stirred at a speed of 200 r / min for 15 min to obtain a mixed solution A. 0.15 g of an oxygen-containing lithium compound (the oxygen-containing lithium compound was composed of Li3PO4 and Li2SiO3 with a mass ratio of 1:1) was added to the mixed solution A and stirred at a speed of 200 r / min for 30 min to obtain a mixed solution B. The mixed solution B was heat-treated in a water bath at 70 °C for 1 h to obtain an electrolyte precursor. The electrolyte precursor was placed in a sealed quartz crucible, heated to 500 °C at a rate of 5 °C / min, and calcined at 500 °C for 10 h to obtain a sulfide solid electrolyte composite material. The sulfide solid electrolyte composite material and polytetrafluoroethylene with a mass ratio of 95:5 were ground evenly to obtain a solid electrolyte mixture.

[0061] The nickel-cobalt-manganese cathode material NCM811, SuperP conductive carbon black, and polyvinylidene fluoride with a mass ratio of 85:10:5 were mixed, and then N-methylpyrrolidone was added, and the mixture was stirred at a speed of 100 r / min for 3 h to obtain a cathode slurry. Among them, the total mass of the nickel-cobalt-manganese cathode material NCM811, SuperP conductive carbon black, and polyvinylidene fluoride was the same as the mass of N-methylpyrrolidone. The graphite, acetylene black, and polyvinylidene fluoride with a mass ratio of 85:10:5 were mixed, and then N-methylpyrrolidone was added, and the mixture was stirred at a speed of 100 r / min for 3 h to obtain a negative electrode slurry. Among them, the total mass of graphite, acetylene black, and polyvinylidene fluoride was the same as the mass of N-methylpyrrolidone.

[0062] The cathode slurry was coated on one side of a carbon fiber woven cloth with a carbon fiber diameter of 7 μm and a cloth surface density of 20 g / m 2 , the coating amount of the cathode slurry was 10 mg / cm 2 , dried at 80 °C for 20 min, and then roll-pressed at 60 °C at a speed of 1 m / min and a linear pressure of 60 kN / m to obtain a carbon fiber cathode. The negative electrode slurry was coated on one side of another carbon fiber woven cloth with a carbon fiber diameter of 7 μm and a cloth surface density of 20 g / m 2 , the coating amount of the negative electrode slurry was 10 mg / cm 2 , dried at 80 °C for 20 min, and then roll-pressed at 60 °C at a speed of 1 m / min and a linear pressure of 60 kN / m to obtain a carbon fiber negative electrode. With a unit area mass of 5 g / m 2, a glass fiber woven fabric with a thickness of 8 μm is used as the separator. Under a nitrogen atmosphere, a solid electrolyte mixture is laid on the side of the positive electrode paste of the carbon fiber positive electrode to form an intermediate film, and the laying thickness of the solid electrolyte mixture is 30 μm. Then, the glass fiber woven fabric and the carbon fiber negative electrode are sequentially stacked on the intermediate film, and the side of the carbon fiber negative electrode coated with the negative electrode paste is in contact with the glass fiber woven fabric. Finally, it is placed under hot pressing and encapsulation at 80 °C and 10 MPa for 10 min to obtain a structural energy storage integrated lithium-ion battery.

[0063] Example 2

[0064] Under an argon atmosphere, 25 g of Li7P3S 11 solid electrolyte powder is added to 250 mL of isopropanol and stirred at a rotation speed of 300 r / min for 20 min to obtain a mixed solution A. 0.25 g of an oxygen-containing lithium compound (the oxygen-containing lithium compound is composed of Li3PO4 and Li2AlO2 with a mass ratio of 1:2) is added to the mixed solution A and stirred at a rotation speed of 300 r / min for 20 min to obtain a mixed solution B. The mixed solution B is heat-treated in a water bath at 60 °C for 1 h to obtain an electrolyte precursor. The electrolyte precursor is placed in a sealed quartz crucible, heated to 450 °C at a rate of 8 °C / min, and calcined at 450 °C for 6 h to obtain a sulfide solid electrolyte composite material. The sulfide solid electrolyte composite material and polytetrafluoroethylene with a mass ratio of 95:5 are ground evenly to obtain a solid electrolyte mixture.

[0065] The lithium iron phosphate positive electrode material, vapor-grown carbon fiber VGCF, and polytetrafluoroethylene with a mass ratio of 85:10:5 are mixed, and then N-methylpyrrolidone is added and stirred at a rotation speed of 100 r / min for 2 h to obtain a positive electrode paste. Among them, the total mass of the lithium iron phosphate positive electrode material, vapor-grown carbon fiber VGCF, and polytetrafluoroethylene is the same as the mass of N-methylpyrrolidone. The tin-based alloy powder (the mass ratio of Sn, Co, and C in the tin-based alloy is 75:20:5), SuperP conductive carbon black, and polyvinylidene fluoride with a mass ratio of 85:10:5 are mixed, and then N-methylpyrrolidone is added and stirred at a rotation speed of 100 r / min for 2 h to obtain a negative electrode paste. Among them, the total mass of the tin-based alloy powder, SuperP conductive carbon black, and polyvinylidene fluoride is the same as the mass of N-methylpyrrolidone.

[0066] The positive electrode paste is coated on one side of a carbon fiber woven fabric with a carbon fiber diameter of 6 μm and a fabric surface density of 28 g / m 2 , and the coating amount of the positive electrode paste is 10 mg / cm 2, dried at 80 °C for 20 min, then roll-pressed at 60 °C at a speed of 1 m / min and a linear pressure of 60 kN / m to obtain a carbon fiber positive electrode. The negative electrode slurry was coated on one side of another carbon fiber woven fabric with a carbon fiber diameter of 6 μm and a fabric surface density of 28 g / m 2 , and the coating amount of the negative electrode slurry was 10 mg / cm 2 , dried at 80 °C for 20 min, then roll-pressed at 60 °C at a speed of 1 m / min and a linear pressure of 60 kN / m to obtain a carbon fiber negative electrode. Using a glass fiber woven fabric with a unit area mass of 12 g / m 2 and a thickness of 10 μm as the separator, in a nitrogen atmosphere, the solid electrolyte mixture was laid on the positive electrode slurry side of the carbon fiber positive electrode to form an intermediate film, and the laying thickness of the solid electrolyte mixture was 30 μm. Then, the glass fiber woven fabric and the carbon fiber negative electrode were sequentially stacked on the intermediate film, and the side of the carbon fiber negative electrode coated with the negative electrode slurry was in contact with the glass fiber woven fabric. Finally, it was placed under heat pressing and encapsulation at 80 °C and 10 MPa for 10 min to obtain a structural energy storage integrated lithium-ion battery.

[0067] Example 3

[0068] In an argon atmosphere, 40 g of Li6PS5Br solid electrolyte powder was added to 500 mL of absolute ethanol and stirred at a rotation speed of 150 r / min for 30 min to obtain a mixed solution A. 0.4 g of an oxygen-containing lithium compound (the oxygen-containing lithium compound was composed of Li3PO4 and Li2TiO3 with a mass ratio of 1:1) was added to the mixed solution A and stirred at a rotation speed of 150 r / min for 45 min to obtain a mixed solution B. The mixed solution B was heat-treated in a water bath at 50 °C for 3 h to obtain an electrolyte precursor. The electrolyte precursor was placed in a closed quartz crucible, heated to 300 °C at a rate of 3 °C / min, pre-calcined at 300 °C for 4 h, and then heated to 550 °C at a rate of 3 °C / min and held for calcination at 550 °C for 10 h to obtain a sulfide solid electrolyte composite material. The sulfide solid electrolyte composite material and polytetrafluoroethylene with a mass ratio of 95:5 were ground evenly to obtain a solid electrolyte mixture.

[0069] The lithium nickel cobalt aluminum oxide positive electrode material NCA, acetylene black, and polytetrafluoroethylene with a mass ratio of 80:15:5 were mixed, and then N-methylpyrrolidone was added and stirred at a rotation speed of 150 r / min for 1 h to obtain a positive electrode slurry. Among them, the total mass of the lithium nickel cobalt aluminum oxide positive electrode material NCA, acetylene black, and polytetrafluoroethylene was the same as the mass of N-methylpyrrolidone.

[0070] The positive electrode slurry was coated on one side of a carbon fiber woven fabric with a carbon fiber diameter of 7 μm and a fabric surface density of 25 g / m 2 , and the coating amount of the positive electrode slurry was 10 mg / cm2 It was dried at 80 °C for 20 min, and then roll-pressed at a speed of 1 m / min and a linear pressure of 60 kN / m at 60 °C to obtain a carbon fiber positive electrode. Molten metallic lithium was coated on one side of another carbon fiber woven fabric with a carbon fiber diameter of 7 μm and a fabric surface density of 25 g / m 2 , and the coating amount of molten metallic lithium was 10 mg / cm 2 . It was dried at 80 °C for 20 min, and then roll-pressed at a speed of 0.5 m / min and a linear pressure of 20 kN / m at 150 °C to obtain a carbon fiber negative electrode. A glass fiber woven fabric with a unit area mass of 15 g / m 2 and a thickness of 9 μm was used as the separator. In a nitrogen atmosphere, the solid electrolyte mixture was laid on the positive electrode paste side of the carbon fiber positive electrode to form an intermediate film, and the laying thickness of the solid electrolyte mixture was 30 μm. Then, the glass fiber woven fabric and the carbon fiber negative electrode were successively stacked on the intermediate film, and the side of the carbon fiber negative electrode coated with molten metallic lithium was in contact with the glass fiber woven fabric. Finally, it was placed under heat pressing and encapsulation at 80 °C and 10 MPa for 10 min to obtain the integrated structural energy storage lithium-ion battery.

[0071] Example 4

[0072] In an argon atmosphere, 30 g of Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 solid electrolyte powder was added to 300 mL of N,N-dimethylformamide and stirred at a rotation speed of 200 r / min for 20 min to obtain a mixed solution A. 0.45 g of an oxygen-containing lithium compound (the oxygen-containing lithium compound was composed of Li3PO4 and Li2CO3 with a mass ratio of 1:1) was added to the mixed solution A and stirred at a rotation speed of 200 r / min for 40 min to obtain a mixed solution B. The mixed solution B was heat-treated in a water bath at 60 °C for 1.5 h to obtain an electrolyte precursor. The electrolyte precursor was placed in a sealed quartz crucible, heated to 200 °C at a rate of 8 °C / min, pre-calcined at 200 °C for 2 h, and then heated to 600 °C at a rate of 8 °C / min and kept at 600 °C for calcination for 8 h to obtain a sulfide solid electrolyte composite material. The sulfide solid electrolyte composite material and polytetrafluoroethylene with a mass ratio of 95:5 were ground evenly to obtain a solid electrolyte mixture.

[0073] Mix the nickel-cobalt-manganese cathode material NCM811, SuperP conductive carbon black, and polyvinylidene fluoride with a mass ratio of 85:10:5, then add N-methylpyrrolidone and stir at a speed of 100 r / min for 3 h to obtain the cathode slurry. Among them, the total mass of the nickel-cobalt-manganese cathode material NCM811, SuperP conductive carbon black, and polyvinylidene fluoride is the same as the mass of N-methylpyrrolidone. Mix the graphite / silicon anode material (the mass content of silicon in the graphite / silicon anode material is 10%) with a mass ratio of 85:10:5, acetylene black, and polyvinylidene fluoride, then add N-methylpyrrolidone and stir at a speed of 100 r / min for 3 h to obtain the anode slurry. Among them, the total mass of the graphite / silicon anode material, acetylene black, and polyvinylidene fluoride is the same as the mass of N-methylpyrrolidone.

[0074] Coat the cathode slurry on one side of a carbon fiber woven cloth with a carbon fiber diameter of 5 μm and a cloth surface density of 28 g / m 2 , and the coating amount of the cathode slurry is 1� mg / cm 2 . Dry it at 80 °C for 20 min, and then roll press it at 60 °C at a speed of 1 m / min and a linear pressure of 60 kN / m to obtain the carbon fiber cathode. Coat the anode slurry on one side of another carbon fiber woven cloth with a carbon fiber diameter of 5 μm and a cloth surface density of 28 g / m 2 , and the coating amount of the anode slurry is 1� mg / cm 2 . Dry it at 80 °C for 20 min, and then roll press it at 60 °C at a speed of 1 m / min and a linear pressure of 60 kN / m to obtain the carbon fiber anode. Use a glass fiber woven cloth with a unit area mass of 10 g / m 2 and a thickness of 8 μm as the separator. Under a nitrogen atmosphere, lay the solid electrolyte mixture on the side of the cathode slurry of the carbon fiber cathode to form an intermediate film, and the laying thickness of the solid electrolyte mixture is 30 μm. Then sequentially stack the glass fiber woven cloth and the carbon fiber anode on top of the intermediate film, with the side of the carbon fiber anode coated with the anode slurry in contact with the glass fiber woven cloth. Finally, place it under hot pressing and encapsulation at 80 °C and 10 MPa for 10 min to obtain the structural energy storage integrated lithium-ion battery.

[0075] Example 5

[0076] Under an argon atmosphere, 35 g of Li7GePS8 solid electrolyte powder was added to 350 mL of dimethyl sulfoxide and stirred at a rotation speed of 100 r / min for 30 min to obtain a mixed solution A. 0.7 g of an oxygen-containing lithium compound (the oxygen-containing lithium compound was composed of Li3PO4 and Li2ZrO3 with a mass ratio of 1:1) was added to the mixed solution A and stirred at a rotation speed of 100 r / min for 60 min to obtain a mixed solution B. The mixed solution B was heat-treated in a water bath at 80 °C for 1 h to obtain an electrolyte precursor. The electrolyte precursor was placed in a sealed quartz crucible, heated to 250 °C at a rate of 6 °C / min, pre-calcined at 250 °C for 3 h, and then heated to 500 °C at a rate of 6 °C / min and calcined at 500 °C for 5 h to obtain a sulfide solid electrolyte composite material. The sulfide solid electrolyte composite material and polytetrafluoroethylene with a mass ratio of 95:5 were ground evenly to obtain a solid electrolyte mixture.

[0077] The nickel-cobalt-manganese cathode material NCM622, SuperP conductive carbon black, and polyvinylidene fluoride with a mass ratio of 85:10:5 were mixed, and then N-methylpyrrolidone was added and stirred at a rotation speed of 100 r / min for 3 h to obtain a cathode slurry. Among them, the total mass of the nickel-cobalt-manganese cathode material NCM622, SuperP conductive carbon black, and polyvinylidene fluoride was the same as the mass of N-methylpyrrolidone.

[0078] The cathode slurry was coated on one side of a carbon fiber woven fabric with a carbon fiber diameter of 7 μm and a fabric surface density of 25 g / m 2 The coating amount of the cathode slurry was 10 mg / cm 2 , dried at 80 °C for 20 min, and then roll-pressed at 60 °C at a speed of 1 m / min and a line pressure of 60 kN / m to obtain a carbon fiber cathode. Molten metallic lithium was coated on one side of another carbon fiber woven fabric with a carbon fiber diameter of 7 μm and a fabric surface density of 25 g / m 2 The coating amount of the molten metallic lithium was 10 mg / cm 2 , dried at 80 °C for 20 min, and then roll-pressed at 150 °C at a speed of 0.5 m / min and a line pressure of 20 kN / m to obtain a carbon fiber anode. A glass fiber woven fabric with a unit area mass of 10 g / m 2 and a thickness of 10 μm was used as a separator. Under a nitrogen atmosphere, the solid electrolyte mixture was laid on the cathode slurry side of the carbon fiber cathode to form an intermediate film, and the laying thickness of the solid electrolyte mixture was 30 μm. Then, the glass fiber woven fabric and the carbon fiber anode were stacked on the intermediate film in sequence, and the side of the carbon fiber anode coated with molten metallic lithium was in contact with the glass fiber woven fabric. Finally, it was placed under heat pressing and encapsulation at 80 °C and 10 MPa for 10 min to obtain a structural energy storage integrated lithium-ion battery.

[0079] The direct current potential method was used to measure the ionic conductivity of the sulfide solid electrolyte composites prepared in Examples 1-5 at 25 °C, and the ionic conductivity after standing in air for 4 h, and the decay rate of the ionic conductivity was calculated. The test results are shown in Table 1.

[0080] Table 1 Ionic conductivity and decay rate of sulfide solid electrolyte composites

[0081]

[0082] As can be seen from Table 1, the sulfide solid electrolyte composite of the present invention has excellent air stability.

[0083] At 25 °C and 0.2C, the integrated structural energy storage lithium-ion batteries prepared in Examples 1-5 were charged and discharged with a voltage range of 2.5-4.2V, and the first-cycle discharge capacity and Coulomb efficiency were tested; then the capacity retention rate after 100 cycles was tested at 0.5C. The test results are shown in Table 2.

[0084] Table 2 Electrochemical performance of integrated structural energy storage lithium-ion batteries

[0085]

[0086] As can be seen from Table 2, the integrated structural energy storage lithium-ion battery of the present invention has excellent specific capacity and excellent cycle stability; among them, the first-cycle discharge capacity of the integrated structural energy storage lithium-ion battery of Example 2 is as high as 165 mAh / g, close to the theoretical limit capacity, indicating that the energy utilization rate of the sulfide solid electrolyte composite of the present invention after coordination with the Sn-Co-C negative electrode is relatively high.

[0087] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A sulfide solid electrolyte composite material, characterized in that, It includes a core and a coating layer, and the coating layer covers the surface of the core; The core is a sulfide solid electrolyte, and the coating layer is an oxygen-containing lithium compound; The oxygen-containing lithium compound includes at least two of Li2AlO2, Li2TiO3, Li2ZrO3, Li3PO4, Li2SO4, Li2CO3, and Li2SiO3.

2. The sulfide solid electrolyte composite material according to claim 1, characterized in that, The mass of the coating layer is 0.1-5% of the mass of the core.

3. The sulfide solid electrolyte composite material according to claim 2, characterized in that The sulfide solid electrolyte is Li (7-a) PS (6-a) X a , Li7P3S 11 , Li 10 GeP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , Li7GePS8 or Li4SnS4, where X is Cl, Br or I, and 0.5 ≤ a ≤ 1.

75.

4. The preparation method of the sulfide solid electrolyte composite material according to any one of claims 1 to 3, characterized in that, It includes the following steps: 1) Dispersing the sulfide solid electrolyte in an organic solvent to obtain a mixed solution A; 2) Adding an oxygen-containing lithium compound to the mixed solution A to obtain a mixed solution B; 3) Performing heat treatment on the mixed solution B to obtain an electrolyte precursor; 4) Calcining the electrolyte precursor to obtain the sulfide solid electrolyte composite material.

5. The preparation method according to claim 4, characterized in that, The organic solvent in step 1) includes one or more of anhydrous ethanol, isopropanol, acetone, dimethyl sulfoxide, and N,N-dimethylformamide; The mass-volume ratio of the sulfide solid electrolyte to the organic solvent is 1 g: 10-15 mL.

6. The preparation method according to claim 4 or 5, characterized in that, The temperature of the heat treatment in step 3) is 30-160 °C, and the time of the heat treatment is 0.5-24 h.

7. The preparation method according to claim 6, characterized in that, The temperature of the calcination in step 4) is 150-650 °C, the time of the calcination is 0.5-24 h, and the heating rate for raising the temperature to the calcination temperature is 3-10 °C / min.

8. An integrated structural energy storage lithium-ion battery, characterized in that, The electrode material of the integrated structural energy storage lithium-ion battery is a composite material based on a carbon fiber woven cloth as the substrate, the separator is a glass fiber woven cloth, and the solid electrolyte is the sulfide solid electrolyte composite material according to any one of claims 1-3.

9. The integrated lithium-ion battery with structural energy storage according to claim 8, characterized in that, The surface density of the carbon fiber woven cloth ≤ 30 g / ㎡, and the diameter of the carbon fiber in the carbon fiber woven cloth ≤ 7 μm; The unit area mass of the glass fiber woven cloth ≤ 15 g / ㎡, and the thickness of the glass fiber woven cloth ≤ 10 μm.

10. The preparation method of the integrated structural energy storage lithium-ion battery according to claim 8 or 9, characterized in that, It includes the following steps: 1) Coating the positive electrode paste on the carbon fiber woven cloth to obtain a carbon fiber positive electrode; coating the negative electrode paste on the carbon fiber woven cloth to obtain a carbon fiber negative electrode; 2) Sequentially encapsulating the carbon fiber positive electrode, the solid electrolyte, the glass fiber woven cloth, and the carbon fiber negative electrode to obtain the integrated structural energy storage lithium-ion battery; The solid electrolyte is the sulfide solid electrolyte composite material according to any one of claims 1-3.

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