Solid-state electrolyte and preparation method and application thereof

Abstract

The application belongs to the technical field of lithium batteries, and relates to a solid-state electrolyte, which comprises inorganic electrolyte powder, rigid ceramic particles and a polymer three-dimensional network structure, wherein the polymer three-dimensional network structure is coated on the surface of the rigid ceramic particles. After the polymer is coated on the surface of the rigid ceramic particles and mixed with the solid-state electrolyte and heated and pressurized, the polymer is transformed into a three-dimensional network structure, and the solid-state electrolyte is densified at the same time. The rigid ceramic particles play a stress conduction role. Further heating makes the low-molecular-weight polymer further polymerize, and the strength of the polymer three-dimensional network structure is enhanced, so that the mechanical strength of the solid-state electrolyte is improved, and the influence on the electrical conductivity is small.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and relates to a solid-state electrolyte and a preparation method and application thereof. BACKGROUND

[0002] Currently, commercial batteries on the market are mainly liquid electrolyte lithium batteries. Since the liquid electrolyte is flammable and the separator is easily pierced by lithium dendrites generated in the battery cycle process, the safety problem of lithium ion batteries has gradually attracted attention. The traditional lithium ion battery based on electrolyte is difficult to eliminate the safety hazard from the nature, and the safety problem of the liquid electrolyte lithium battery is still very prominent, and thermal runaway is difficult to avoid completely.

[0003] And the solid-state lithium ion electrolyte can effectively reduce the occurrence of safety accidents of lithium ion batteries because of its stable chemical properties and difficulty in combustion, and theoretically there is no safety problem. The solid-state electrolyte can be generally prepared by dry method (PTFE-based) and wet method, wherein the efficiency of the dry method is relatively low, and it is difficult to make the electrolyte sheet thin, and the mass production is also difficult. The adhesive used in the wet method has an obvious influence on the electrical conductivity, and the mechanical properties are poor due to the small amount of adhesive (<5%). SUMMARY

[0004] The application aims to provide a solid-state electrolyte and a preparation method and application thereof. The polymer is coated on the surface of the rigid ceramic particles, and then mixed with the solid-state electrolyte and heated and pressed, so that the polymer is transformed into a three-dimensional network structure, and the solid-state electrolyte is densified. The rigid ceramic particles play a stress conduction role, and further heating makes the low molecular weight polymer further polymerize, thereby enhancing the strength of the three-dimensional network structure of the polymer, improving the mechanical strength of the solid-state electrolyte, and having little influence on the electrical conductivity.

[0005] In a first aspect, the application provides a solid-state electrolyte, comprising inorganic electrolyte powder, rigid ceramic particles and a three-dimensional network structure of a polymer, wherein the three-dimensional network structure of the polymer is coated on the surface of the rigid ceramic particles.

[0006] In some embodiments, the rigid ceramic particles comprise one or more of Al2O3, SiO2, ZrO2, SiC, BN and Si3N4.

[0007] Preferably, the median particle size D50 of the rigid ceramic particles is 0.1-50 μm.

[0008] In some embodiments, the inorganic electrolyte powder is selected from one or a mixture of several of the following:

[0009] (1) xLi a B·yC c Dd • ZP2S5, 0≤x<100, 0≤y<100, 0≤z<100, a=1 or 2, c=1 or 2, d=1, 2 or 5, B is S, Cl, Br or I, C is Li, Si, Ge, P, Sn or Sb, D is Cl, Br, I, O, S or Se;

[0010] (2) Li 1+x M x Ti 2-x (PO4)3, 0

[0011] (3) Li 0.5-3x La 0.5+x TiO3, 0

[0012] (4) Li 7-x La3Zr 2-x M x O 12 , 0≤x≤2, M is Zr, Hf, Sn, Nb, Y, W or Ta;

[0013] Preferably, the inorganic electrolyte powder has a median particle size D50 of 0.5-100 μm.

[0014] Preferably, the inorganic electrolyte powder has a weight ratio of 50%-99.9% in the solid-state electrolyte.

[0015] In some embodiments, the polymer includes one or more of styrene-ethylene-butylene-styrene copolymer, styrene-butadiene-styrene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, chlorosulfonated polyethylene, polyisobutylene, butadiene-styrene copolymer, polyacrylate, polyvinylidene fluoride, polyarylsulfone, polyethersulfone, cellulose, polystyrene, polycarbonate, polyvinyl chloride, polyamide, polyimide, polyurethane, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, polyvinyl alcohol, polylactic acid, polyethylene oxide, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, carboxymethylcellulose sodium, polyphenylene sulfide, polyether ether ketone, polyether ketone, and a mixture of one or more of polyether ketone.

[0016] Preferably, the polymer has a molecular weight of less than or equal to 10,000.

[0017] Preferably, the polymer contains 1-5 wt% BPO.

[0018] In some embodiments, the polymer three-dimensional network structure coated on the surface of the rigid ceramic particles has a thickness of 1-50 μm.

[0019] In a second aspect, the present application provides a method for preparing a solid-state electrolyte, comprising the following steps:

[0020] Step 1, preparing reinforced particles: coating a polymer on the surface of rigid ceramic particles to obtain core-shell reinforced particles;

[0021] Step 2, preparing a solid-state electrolyte: mixing inorganic electrolyte powder with the core-shell reinforced particles, and then densifying at 60-100℃ and 200-300MPa for 1-2h to obtain a densified solid-state electrolyte;

[0022] Step 3, cross-linking polymerization: placing the prepared densified solid-state electrolyte in an environment of 100-150℃ for 4-9h to cross-link and polymerize the low-molecular-weight polymer, thereby obtaining a solid-state electrolyte.

[0023] In some embodiments, the temperature for densification is 80-100℃, the pressure is 250-300MPa, and the time is 1.5-2h;

[0024] Preferably, the temperature for cross-linking polymerization is 140-150℃, and the time is 8-9h.

[0025] In some embodiments, the mixing method for mixing the inorganic electrolyte powder with the core-shell reinforced particles is one or more of a kneader, an internal mixer, a screw extruder, and a rubber mixer.

[0026] In some embodiments, the rigid ceramic particles comprise one or more of Al2O3, SiO2, ZrO2, SiC, BN, and Si3N4.

[0027] Preferably, the D50 of the rigid ceramic particles is 0.1-50μm.

[0028] Preferably, the inorganic electrolyte powder is selected from one or a mixture of several of the following:

[0029] (1) xLi a B·yC c D d ·zP2S5, 0≤x<100, 0≤y<100, 0≤z<100, a=1 or 2, c=1 or 2, d=1, 2 or 5, B is S, Cl, Br or I, C is Li, Si, Ge, P, Sn or Sb, and D is Cl, Br, I, O, S or Se;

[0030] (2) Li 1+x M x Ti 2-x (PO4)3, 0<x<2, and M is Al, In, Ge, Ga, Y, Lu or La;

[0031] (3) Li 0.5-3x La 0.5+x TiO3, 0 < x < 0.15;

[0032] (4) Li 7-x La3Zr 2-x M x O 12 , 0≤x≤2, the M is Zr, Hf, Sn, Nb, Y, W or Ta;

[0033] Preferably, the inorganic electrolyte powder D50 is 0.5-100 μm;

[0034] Preferably, the weight ratio of the inorganic electrolyte powder in the solid-state electrolyte is 50%-99.9%;

[0035] Preferably, the polymer includes one or more of styrene-ethylene-butylene-styrene copolymer, styrene-butadiene-styrene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, chlorosulfonated polyethylene, polyisobutylene, butadiene-styrene copolymer, polyacrylate, polyvinylidene fluoride, polyarylsulfone, polyethersulfone, cellulose, polystyrene, polycarbonate, polyvinyl chloride, polyamide, polyimide, polyurethane, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, polyvinyl alcohol, polylactic acid, polyethylene oxide, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, carboxymethylcellulose sodium, polyphenylene sulfide, polyether ether ketone, polyether ketone and polyether ketone mixture;

[0036] Preferably, the molecular weight of the polymer is less than or equal to 10000;

[0037] Preferably, the polymer contains 1-5 wt% BPO;

[0038] Preferably, the thickness of the three-dimensional network structure of the polymer coated on the surface of the rigid ceramic particles is 1-50 μm.

[0039] In a third aspect, the application provides a use of the above solid-state electrolyte in the preparation of a lithium battery.

[0040] In summary, the present application includes at least one of the following beneficial technical effects:

[0041] The core-shell reinforced particles are formed by coating the polymer on the surface of the rigid ceramic particles, and then the reinforced particles are mixed with the solid electrolyte and heated and pressurized, so that the polymer is transformed into a three-dimensional network structure, and the solid electrolyte is densified. Since the network polymer has pores, the contact area with the solid electrolyte particles is small, and the conductivity is less affected. In addition, the polymer is coated on the rigid ceramic particles, which is beneficial to the pulverization and dispersion of the polymer. The rigid ceramic particles play a stress conducting role in the reinforced composite solid electrolyte, improving the mechanical strength of the solid electrolyte. Further heating makes the low molecular weight polymer further polymerize, enhancing the strength of the three-dimensional network structure of the polymer. DETAILED DESCRIPTION

[0042] The technical solutions of the present application are further illustrated by specific examples below, which do not represent a limitation on the scope of protection of the present application. Some non-essential modifications and adjustments made by others according to the concept of the present application still fall within the scope of protection of the present application.

[0043] Example 1

[0044] A solid electrolyte includes inorganic electrolyte powder, rigid ceramic particles and a three-dimensional network structure of polymer, and the three-dimensional network structure of polymer is coated on the surface of the rigid ceramic particles.

[0045] In some embodiments, the rigid ceramic particles include one or more of Al2O3, SiO2, ZrO2, SiC, BN, Si3N4; such as Al2O3 rigid ceramic particles, SiO2 rigid ceramic particles, ZrO2 rigid ceramic particles, SiC rigid ceramic particles, BN rigid ceramic particles, Si3N4 rigid ceramic particles, a mixture of Al2O3 rigid ceramic particles and SiO2 rigid ceramic particles, a mixture of ZrO2 rigid ceramic particles and SiC rigid ceramic particles, etc.

[0046] In some embodiments, the median particle size D50 of the particle rigid ceramic particles is 0.1-50 μm, such as D50 of the particle rigid ceramic particles being 0.1 μm, D50 of the particle rigid ceramic particles being 10 μm, D50 of the particle rigid ceramic particles being 20 μm, D50 of the particle rigid ceramic particles being 50 μm, etc.

[0047] In some embodiments, the inorganic electrolyte powder is selected from one or more of the following:

[0048] (1) xLi a B·yC c D d• ZP2S5, 0≤x<100, 0≤y<100, 0≤z<100, a=1 or 2, c=1 or 2, d=1, 2 or 5, B is S, Cl, Br or I, C is Li, Si, Ge, P, Sn or Sb, D is Cl, Br, I, O, S or Se;

[0049] (2) Li 1+x M x Ti 2-x (PO4)3, 0

[0050] (3) Li 0.5-3x La 0.5+x TiO3, 0

[0051] (4) Li 7-x La3Zr 2-x M x O 12 , 0≤x≤2, M is Zr, Hf, Sn, Nb, Y, W or Ta;

[0052] In some embodiments, the inorganic electrolyte powder has a median particle size D50 of 0.5-100 μm.

[0053] In some embodiments, the inorganic electrolyte powder has a weight ratio in the solid-state electrolyte of 50%-99.9%.

[0054] In some embodiments, the polymer includes one or more of styrene-ethylene-butylene-styrene copolymer, styrene-butadiene-styrene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, chlorosulfonated polyethylene, polyisobutylene, butadiene-styrene copolymer, polyacrylate, polyvinylidene fluoride, polyarylsulfone, polyethersulfone, cellulose, polystyrene, polycarbonate, polyvinyl chloride, polyamide, polyimide, polyurethane, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, polyvinyl alcohol, polylactic acid, polyethylene oxide, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, carboxymethylcellulose sodium, polyphenylene sulfide, polyether ether ketone, polyether ketone, and polyether ketone; such as styrene-ethylene-butylene-styrene copolymer, polyarylsulfone, polyethersulfone, polyphenylene sulfide, polyether ether ketone, polyethylene oxide, and acrylonitrile-butadiene copolymer mixture, etc.

[0055] In some embodiments, the polymer has a molecular weight of less than or equal to 10,000; such as 3,000, 5,000, 7,000, 9,000, 10,000, etc.

[0056] In some embodiments, the polymer contains BPO at a content of 1-5 wt%, such as 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, etc.

[0057] In some embodiments, the thickness of the polymer three-dimensional network structure coated on the surface of the rigid ceramic particles is 1-50 μm; such as 1 μm, 5 μm, 15 μm, 25 μm, 35 μm, 50 μm, etc.

[0058] In this embodiment, the polymer is styrene-ethylene-butylene-styrene copolymer, containing 2 wt% BPO, with a molecular weight of 5000, the rigid ceramic particles are Al2O3, with a D50 of 2 μm, and the inorganic electrolyte powder is Li 10 Sn 0.7 Si 0.3 P2S 12 with a D50 of 10 μm.

[0059] Example 2

[0060] A method for preparing a lithium ion solid-state electrolyte, comprising the following steps:

[0061] Step 1, preparation of reinforced particles

[0062] The surface of the rigid ceramic particles is coated with a polymer to obtain core-shell reinforced particles.

[0063] In some embodiments, the rigid ceramic particles are one or more of Al2O3, SiO2, ZrO2, SiC, BN, Si3N4, such as Al2O3 rigid ceramic particles, SiO2 rigid ceramic particles, ZrO2 rigid ceramic particles, SiC rigid ceramic particles, BN rigid ceramic particles, Si3N4 rigid ceramic particles, a mixture of Al2O3 rigid ceramic particles and SiO2 rigid ceramic particles, a mixture of ZrO2 rigid ceramic particles and SiC rigid ceramic particles, etc.

[0064] In some embodiments, the median particle size D50 of the particle rigid ceramic particles is 0.1-50 μm; such as 0.1 μm, 10 μm, 20 μm, 50 μm, etc.

[0065] In some embodiments, the polymer is one or more of styrene-ethylene-butylene-styrene copolymer, styrene-butadiene-styrene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, chlorosulfonated polyethylene, polyisobutylene, butadiene-styrene copolymer, polyacrylate, polyvinylidene fluoride, polyarylsulfone, polyethersulfone, cellulose, polystyrene, polycarbonate, polyvinyl chloride, polyamide, polyimide, polyurethane, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, polyvinyl alcohol, polylactic acid, polyethylene oxide, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, carboxymethylcellulose sodium, polyphenylene sulfide, polyether ether ketone, polyether ketone, and a mixture thereof, such as styrene-ethylene-butylene-styrene copolymer, polyarylsulfone, polyethersulfone, polyphenylene sulfide, polyether ether ketone, polyethylene oxide, and acrylonitrile-butadiene copolymer mixture, etc.

[0066] In some embodiments, the molecular weight of the polymer is less than or equal to 10,000; such as 3,000, 5,000, 7,000, 9,000, 10,000, etc.

[0067] In some embodiments, the content of BPO in the polymer is 1-5 wt%, such as 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, etc.

[0068] In some embodiments, the thickness of the three-dimensional network structure of the polymer coated on the surface of the rigid ceramic particles is 1-50 μm, such as 1 μm, 5 μm, 15 μm, 25 μm, 35 μm, 50 μm, etc.

[0069] In this embodiment, the core-shell reinforced particles are prepared as follows: a styrene-ethylene-butylene-styrene copolymer with a molecular weight of 5,000 (containing 2 wt% BPO) is dissolved in a xylene solution, Al2O3 (D50: 2 μm) rigid ceramic particles are added, and stirred uniformly, and then dried to obtain core-shell reinforced particles with a coating layer thickness of 3 μm.

[0070] Step 2, preparation of solid electrolyte

[0071] The inorganic electrolyte powder and the core-shell reinforced particles are mixed uniformly, and then densified at 60-100 °C and 200-300 MPa for 1-2 h to obtain a densified solid electrolyte. For example, the densification temperature is 60 °C, 70 °C, 100 °C, 75 °C, 80 °C, 90 °C, 100 °C, etc.; the densification pressure is 200 MPa, 210 MPa, 220 MPa, 230 MPa, 240 MPa, 250 MPa, 260 MPa, 270 MPa, 280 MPa, 290 MPa, 300 MPa, etc.; and the densification time is 1 h, 1.3 h, 1.5 h, 2 h, etc.

[0072] In some embodiments, the inorganic electrolyte powder is selected from one or a mixture of several of the following:

[0073] (1) x Li a B • y C c D d • z P2S5, 0 < x < 100, 0 < y < 100, 0 < z < 100, a = 1 or 2, c = 1 or 2, d = 1, 2 or 5, B is S, Cl, Br or I, C is Li, Si, Ge, P, Sn or Sb, D is Cl, Br, I, O, S or Se;

[0074] (2) Li 1+x M x Ti 2-x (PO4)3, 0 < x < 2, M is Al, In, Ge, Ga, Y, Lu or La;

[0075] (3) Li 0.5-3x La 0.5+x TiO3, 0 < x < 0.15;

[0076] (4) Li 7-x La3Zr 2-x M x O 12 , 0 < x < 2, M is Zr, Hf, Sn, Nb, Y, W or Ta;

[0077] For example, the inorganic electrolyte powder is Li 10 Sn 0.7 Si 0.3 P2S 12 powder, Li3PS4powder, Li 10 GeP2S 12 powder, Li 11 Si2PS 12 powder, Li 3.25 Ge 0.25 P 0.75 S4powder, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 powder, Li3PS4powder and Li 10 GeP2S 12 powder, a mixture of Li

[0078] In some embodiments, the inorganic electrolyte powder D50 is 0.5-100 pm; such as inorganic electrolyte powder D50 is 0.5 pm, inorganic electrolyte powder D50 is 10 pm, inorganic electrolyte powder D50 is 25 pm, inorganic electrolyte powder D50 is 50 pm, inorganic electrolyte powder D50 is 100 pm, etc.

[0079] In some embodiments, the weight ratio of the inorganic electrolyte powder in the solid-state electrolyte is 50%-99.9%; such as 50%, 60%, 70%, 80%, 90%, 99.9%, etc.

[0080] In some embodiments, the mixing method of the inorganic electrolyte powder and the core-shell reinforced particles is one or more of the following: kneader, internal mixer, screw extruder, rubber mixing machine, etc. For example, the inorganic electrolyte powder and the core-shell reinforced particles are mixed by a kneader, mixed by an internal mixer, mixed by a screw extruder, or mixed by a rubber mixing machine, etc.

[0081] In this embodiment, the specific method of densifying the solid-state electrolyte is as follows: 90 parts by mass of Li 10 Sn 0.7 Si 0.3 P2S 12 powder (D50: 10 pm) and 10 parts by mass of core-shell reinforced particles are mixed by shearing in a kneader for 1 h, and then densified at 60°C and 200 MPa for 1 h. The polymer deforms to form a three-dimensional network structure, and a densified solid-state electrolyte is obtained.

[0082] Step 3, cross-linking polymerization

[0083] The prepared densified solid-state electrolyte is treated in an environment of 100-150°C for 4-9h, and the low molecular weight polymer is cross-linked and polymerized to obtain a solid-state electrolyte. For example, the temperature is 100°C, 110°C, 120°C, 125°C, 130°C, 140°C, 150°C, etc., and the time is 4h, 4.5h, 5h, 5.5h, 6h, 7h, 8h, 9h, etc.

[0084] In this embodiment, the prepared densified solid-state electrolyte is coated by a roll coater, treated in an environment of 110°C for 5h, and the low molecular weight polymer is cross-linked and polymerized to obtain a solid-state electrolyte.

[0085] Example 3

[0086] A preparation method of a lithium ion solid-state electrolyte, comprising the following steps:

[0087] Step 1, Preparation of reinforced particles: Vinylidene fluoride-hexafluoropropylene copolymer (molecular weight 7000, containing 2wt% BPO) is coated on the surface of SiO2 (D50: 1 μm) rigid ceramic particles to prepare core-shell reinforced particles with a 1 μm thick coating layer;

[0088] Step 2, Preparation of solid electrolyte: 80 parts by mass of Li3PS4 (D50: 5 μm) and 20 parts by mass of core-shell reinforced particles are mixed in a Banbury mixer at room temperature for 1.5 h, and then densified at 90°C and 200 MPa for 1 h to deform the polymer into a three-dimensional network structure, thereby obtaining a densified solid electrolyte;

[0089] Step 3, Crosslinking polymerization: The prepared densified solid electrolyte is treated at 130°C for 4 h to crosslink and polymerize the low-molecular-weight polymer, thereby obtaining a solid electrolyte.

[0090] Example 4

[0091] A method for preparing a lithium ion solid electrolyte, comprising the following steps:

[0092] Step 1, Preparation of reinforced particles: Chlorosulfonated polyethylene (molecular weight 10000, containing 2wt% BPO) is coated on the surface of ZrO2 (D50: 7 μm) rigid ceramic particles to prepare core-shell reinforced particles with a 5 μm thick coating layer;

[0093] Step 2, Preparation of solid electrolyte: 70 parts by mass of Li 10 GeP2S 12 (D50: 15 μm) and 30 parts by mass of core-shell reinforced particles are mixed in a screw extruder at room temperature for 2 h, and then densified at 100°C and 300 MPa for 1 h to deform the polymer into a three-dimensional network structure, thereby obtaining a densified solid electrolyte;

[0094] Step 3, Crosslinking polymerization: The prepared densified solid electrolyte is treated at 150°C for 9 h to crosslink and polymerize the low-molecular-weight polymer, thereby obtaining a solid electrolyte.

[0095] Example 5

[0096] A method for preparing a lithium ion solid electrolyte, comprising the following steps:

[0097] Step 1, Preparation of reinforced particles: Styrene-butadiene-styrene copolymer (molecular weight 9000, containing 2wt% BPO) is coated on the surface of SiC (D50: 3 μm) rigid ceramic particles to prepare core-shell reinforced particles with a 2 μm thick coating layer;

[0098] Step 2, Preparation of solid electrolyte: 95 parts by mass of Li 11Si2PS 12 (D50: 7 pm) and 5 parts by mass of the core-shell reinforcing particles were mixed in a rubber mixer for 2 h, and densification was performed at 80 °C under 300 MPa for 1.5 h, and the polymer was deformed to form a three-dimensional network structure, to obtain a densified solid-state electrolyte;

[0099] Step 3, cross-linking polymerization: the prepared densified solid-state electrolyte was treated at 115 °C for 7 h, and the low-molecular-weight polymer was cross-linked and polymerized, to obtain a solid-state electrolyte.

[0100] Example 6

[0101] A preparation method of a lithium ion solid-state electrolyte, comprising the following steps:

[0102] Step 1, preparation of reinforcing particles: a polyisobutylene copolymer (containing 2 wt% BPO) with a molecular weight of 5000 was coated on the surface of BN (D50: 5 pm) rigid ceramic particles, to obtain core-shell reinforcing particles with a coating layer thickness of 4 pm;

[0103] Step 2, preparation of a solid-state electrolyte: 60 parts by mass of Li 3.25 Ge 0.25 P 0.75 S4 (D50: 16 pm) and 40 parts by mass of the core-shell reinforcing particles were mixed in a rubber mixer for 1.5 h, and densification was performed at 90 °C under 200 MPa for 1 h, and the polymer was deformed to form a three-dimensional network structure, to obtain a densified solid-state electrolyte;

[0104] Step 3, cross-linking polymerization: the prepared densified solid-state electrolyte was treated at 130 °C for 4 h, and the low-molecular-weight polymer was cross-linked and polymerized, to obtain a solid-state electrolyte.

[0105] Example 7

[0106] A preparation method of a lithium ion solid-state electrolyte, comprising the following steps:

[0107] Step 1, preparation of reinforcing particles: a polyisobutylene copolymer (containing 2 wt% BPO) with a molecular weight of 3000 was coated on the surface of Si3N4 (D50: 1 pm) rigid ceramic particles, to obtain core-shell reinforcing particles with a coating layer thickness of 1 pm;

[0108] Step 2, preparation of a solid-state electrolyte: 99 parts by mass of Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3(D50: 6μm) and 1 part by mass of core-shell reinforced particles were sheared and mixed in an internal mixer for 1.5h, and then densified at 70℃ and 200MPa for 1h. The polymer was deformed to form a three-dimensional network structure, and a densified solid electrolyte was obtained.

[0109] Step 3, cross-linking polymerization: The densified solid electrolyte is treated at 100°C for 5 hours to cross-link and polymerize the low molecular weight polymer to obtain the solid electrolyte.

[0110] Example of effect

[0111] The tensile properties and electrochemical impedance spectroscopy of the solid electrolytes obtained in Examples 2-7 were tested, and the results are shown in the table below:

[0112]

[0113] As can be seen from the table above, the solid electrolytes prepared in Examples 2-7 of this invention have high tensile strength and lithium-ion conductivity. This demonstrates that coating the polymer onto rigid ceramic particles facilitates polymer powdering and dispersion. Since the rigid ceramic particles act as stress conductors in the reinforced composite solid electrolyte, the mechanical strength of the solid electrolyte is improved. Furthermore, by coating the surface of the rigid ceramic particles with polymer to form core-shell reinforcing particles, and then mixing the reinforcing particles with the solid electrolyte and heating and pressurizing, the polymer is transformed into a three-dimensional network structure, simultaneously densifying the solid electrolyte. Because the network polymer is porous, the contact area with the solid electrolyte particles is small, thus having a minimal impact on conductivity.

[0114] Comparative Example 1, based on Example 2, investigates the effect of core-shell reinforcing particles on the results.

[0115] A method for preparing a lithium-ion solid electrolyte includes the following steps:

[0116] S1. Preparation of solid electrolyte: At room temperature, directly add 90 parts by mass of Li 10 Sn 0.7 Si 0.3 P2S 12 Powder (D50: 10μm), 0.72 parts by weight of Al2O3 rigid ceramic particles (D50: 2μm), and 9.28 parts by weight of styrene-ethylene-butene-styrene copolymer with a molecular weight of 5000 (D50: 3μm, containing 2wt% BPO) were shear-mixed in a kneader for 1 h, and then densified at 60℃ and 200MPa for 1 h. The polymer deformed to form a three-dimensional network structure, thus obtaining a densified solid electrolyte.

[0117] S2, Crosslinking polymerization: The densified solid electrolyte is treated at 110°C for 5 hours to crosslink and polymerize the low molecular weight polymer to obtain the solid electrolyte.

[0118] Comparative Example 2 is based on Example 2, to investigate the effect of core-shell reinforced particles on the results

[0119] A preparation method of a lithium ion solid-state electrolyte, comprising the following steps:

[0120] S1, preparation of a solid-state electrolyte: directly mix 90 parts by mass of Li 10 Sn 0.7 Si 0.3 P2S 12 powder (D50: 10 μm) and 10 parts by mass of Al2O3 rigid ceramic particles (D50: 2 μm) in a kneader for 1 h, and densify at 60°C and 200 MPa for 1 h, and the polymer deforms to form a three-dimensional network structure, to obtain a densified solid-state electrolyte;

[0121] S2, cross-linking polymerization: place the prepared densified solid-state electrolyte in an environment at 110°C for 5 h, and cross-link and polymerize the low-molecular-weight polymer, to obtain a solid-state electrolyte.

[0122] Comparative Example 3 is based on Example 2, to investigate the effect of core-shell reinforced particles on the results

[0123] A preparation method of a lithium ion solid-state electrolyte, comprising the following steps:

[0124] S1, preparation of a solid-state electrolyte: directly mix 90 parts by mass of Li 10 Sn 0.7 Si 0.3 P2S 12 powder (D50: 10 μm) and 10 parts by mass of a styrene-ethylene-butylene-styrene copolymer with a molecular weight of 5000 (D50: 3 μm, containing 2 wt% BPO) in a kneader for 1 h, and densify at 60°C and 200 MPa for 1 h, and the polymer deforms to form a three-dimensional network structure, to obtain a densified solid-state electrolyte;

[0125] S2, cross-linking polymerization: place the prepared densified solid-state electrolyte in an environment at 110°C for 5 h, and cross-link and polymerize the low-molecular-weight polymer, to obtain a solid-state electrolyte.

[0126] Comparative Example 4 is based on Example 2, to investigate the effect of copolymer components on the results

[0127] A preparation method of a lithium ion solid-state electrolyte, which is different from Example 1 in that the styrene-ethylene-butylene-styrene copolymer does not contain BPO.

[0128] The solid-state electrolytes of Comparative Examples 1-4 are tested in the same way for tensile properties and electrochemical impedance spectroscopy, and the results are shown in the following table:

[0129]

[0130]

[0131] Comparative Example 1 directly mixed the polymer with the inorganic electrolyte powder and the rigid ceramic particles for densification, and the obtained solid-state electrolyte had both far lower tensile strength and lithium ion conductivity than Examples 2-7. Comparative Example 2 directly mixed the inorganic electrolyte powder alone with the rigid ceramic particles, and the obtained solid-state electrolyte had similar lithium ion conductivity but lower tensile strength than Examples 2-7. Comparative Example 3 directly mixed the polymer with the inorganic electrolyte powder for densification, and the obtained solid-state electrolyte had similar lithium ion conductivity but also lower tensile strength than Examples 2-7. This shows that the core-shell reinforced particles composed of the low-molecular-weight polymer coated on the surface of the rigid ceramic particles are beneficial to overcoming the problems of difficulty in powderization and poor dispersibility of pure polymers, and can effectively form a three-dimensional network structure of the polymer and a dual-reinforced structure of the rigid ceramic particles. Since the form of the polymer is mainly network, the contact area with the solid-state electrolyte particles is small, and the polymer has less effect on the conductivity, thus simultaneously improving the tensile strength and lithium ion conductivity of the solid-state electrolyte.

[0132] The styrene-ethylene-butylene-styrene copolymer used in Comparative Example 4 does not contain BPO, and the obtained solid-state electrolyte has similar lithium ion conductivity but lower tensile strength than Examples 2-7. This shows that the polymer containing BPO can effectively improve the tensile strength of the solid-state electrolyte.

[0133] It can be understood that the present application is described by some embodiments, and those skilled in the art know that various changes or equivalent replacements can be made to the features and embodiments without departing from the spirit and scope of the present application. In addition, under the guidance of the present application, the features and embodiments can be modified to adapt to specific conditions and materials without departing from the spirit and scope of the present application. Therefore, the present application is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present application are within the scope of the present application.

Claims

1. A solid state electrolyte, characterized by, The solid-state electrolyte comprises inorganic electrolyte powder, rigid ceramic particles and polymer three-dimensional network structure, the polymer three-dimensional network structure is coated on the surface of the rigid ceramic particles; the polymer contains 1-5wt% BPO; the rigid ceramic particles are one or more of Al2O3, SiO2, ZrO2, SiC, BN and Si3N4; the preparation method of the solid-state electrolyte comprises the following steps: Step 1, preparation of reinforced particles: the surface of the rigid ceramic particles is coated with a polymer to obtain core-shell reinforced particles; Step 2, preparation of solid-state electrolyte: the inorganic electrolyte powder and the core-shell reinforced particles are uniformly mixed, then densification is carried out at 60-100 ℃ and 200-300 MPa for 1-2 h to obtain a densified solid-state electrolyte; Step 3, crosslinking polymerization: the prepared densified solid-state electrolyte is treated in an environment of 100-150 ℃ for 4-9 h to crosslink and polymerize the low-molecular-weight polymer, thereby obtaining a solid-state electrolyte.

2. The solid-state electrolyte of claim 1, wherein, The median particle size D50 of the rigid ceramic particles is 0.1-50 µm.

3. The solid state electrolyte of claim 1, wherein, The inorganic electrolyte powder is selected from one or a mixture of several of the following: (1) xLi a B.yC c D d zP2S5, 0 < x < 100, 0 < y < 100, 0 < z < 100, a = 1 or 2, c = 1 or 2, d = 1, 2 or 5, B is S, Cl, Br or I, C is Li, Si, Ge, P, Sn or Sb, D is Cl, Br, I, O, S or Se; (2) Li 1+x M x Ti 2-x (PO4)3, 0 < x < 2, said M being Al, In, Ge, Ga, Y, Lu or La; (3) Li 0.5-3x La 0 .5+x TiO3, 0 < x < 0.15; (4) Li 7-x La3Zr 2-x M x O 12 , 0≤x≤2, the M is Zr, Hf, Sn, Nb, Y, W or Ta.

4. The solid state electrolyte of claim 1, wherein, The median particle size D50 of the inorganic electrolyte powder is 0.5-100 µm.

5. The solid state electrolyte of claim 1, wherein, The weight ratio of the inorganic electrolyte powder in the solid-state electrolyte is 50%-99.9%.

6. The solid state electrolyte of claim 1, wherein, The polymer comprises one or a mixture of several of polyacrylate, polyvinylidene fluoride, polyaryl sulfone, polyether sulfone, polystyrene, polycarbonate, polyvinyl chloride, polyamide, polyimide and polyurethane.

7. The solid state electrolyte of claim 1, wherein, The polymer comprises one or a mixture of several of styrene-ethylene-butylene-styrene copolymer, styrene-butadiene-styrene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, chlorosulfonated polyethylene, polyisobutylene, butadiene-styrene copolymer, cellulose, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, polyvinyl alcohol, polylactic acid, polyethylene oxide, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, sodium carboxymethyl cellulose, polyphenylene sulfide, polyether ether ketone and polyether ketone.

8. The solid state electrolyte of claim 1, wherein, The molecular weight of the polymer is less than or equal to 10000.

9. The solid state electrolyte of claim 1, wherein, The thickness of the polymer three-dimensional network structure coated on the surface of the rigid ceramic particles is 1-50 µm.

10. The solid state electrolyte of claim 1, wherein, The temperature for densification in step 2 is 80-100 ℃, the pressure is 250-300 MPa, and the time is 1.5-2 h.

11. The solid state electrolyte of claim 1, wherein, The temperature for crosslinking polymerization in step 2 is 140-150 ℃, and the time is 8-9 h.

12. The solid state electrolyte of claim 1, wherein, In step 2, the inorganic electrolyte powder and the core-shell reinforced particles are uniformly mixed by one or more of a kneader, an internal mixer, a screw extruder and a rubber mixing machine.

13. Use of the solid-state electrolyte according to any one of claims 1-12 in the preparation of a lithium battery.

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