A sulfide solid electrolyte material, its preparation method and application

Abstract

This invention belongs to the field of battery materials technology and discloses a sulfide solid electrolyte material, its preparation method, and its application. The sulfide solid electrolyte material of this invention includes a core and a coating layer covering the surface of the core; the core includes a sulfide electrolyte; the coating layer includes an organic-inorganic hybrid polymer. This core-shell structured sulfide solid electrolyte material, through the design and synthesis of a polymer coating layer with a specific B-Al-O backbone and fluorinated silicon end groups, successfully achieves a synergistic balance between low electronic conductivity, high ionic conductivity retention, excellent high-temperature stability, and outstanding cycle performance by surface-modifying the sulfide electrolyte. This effectively overcomes key challenges in existing technologies, such as poor air stability, high-temperature instability, and poor interfacial compatibility with lithium metal anodes, significantly improving the overall electrochemical performance and safety reliability of all-solid-state batteries.

Description

Technical Field

[0001] This invention relates to the field of battery materials technology, specifically to a sulfide solid electrolyte material, its preparation method, and its application. Background Technology

[0002] Against the backdrop of rapid iteration in new energy battery technology, sulfide solid electrolytes are considered one of the most commercially promising electrolyte materials for all-solid-state batteries due to their excellent room-temperature ionic conductivity, good electrode interfacial contact, and superior machinability. The preparation of this type of electrolyte typically requires high-temperature sintering under an inert atmosphere, thus maintaining relatively stable physicochemical properties in an inert environment, laying the foundation for the high energy density and long cycle life of all-solid-state batteries. However, the practical application of existing sulfide solid electrolytes still faces serious safety hazards and performance bottlenecks. Among these, insufficient interfacial thermal stability between the sulfide electrolyte and the high-nickel ternary cathode is one of the core issues hindering its industrialization.

[0003] Studies have found that different structural types of sulfide electrolytes and high-nickel ternary cathodes exhibit differentiated thermal runaway reaction pathways, specifically: glass-ceramic sulfide electrolytes (such as Li3PS4, Li7P3S) exhibit different thermal runaway reaction pathways. 11 At approximately 200℃, crystalline sulfide electrolytes (such as Li6PS5Cl, Li...) undergo a gas-solid oxidation reaction with oxygen released during the delithiation process of high-nickel ternary cathodes, resulting in a large heat release. The total heat generation can reach 2100+ J / g, approximately nine times that of traditional liquid electrolytes. Simultaneously, toxic SO2 gas is produced, posing both safety and environmental risks. 10 GeP2S 12 Although it exhibits some stability against oxygen at around 200℃, when the temperature rises to around 300℃, it undergoes a solid-solid reaction with transition metal oxides and other products generated by the decomposition of the high-nickel ternary cathode, generating approximately 1000+ J / g of heat, which also poses a risk of thermal runaway. When the battery experiences abnormal operating conditions such as a short circuit, the aforementioned thermal runaway reaction can cause a sudden rise in cell temperature due to localized high-current discharge, leading to the release of large amounts of oxygen from the cathode, damage to the internal structure of the cell, and ultimately inducing serious safety accidents such as sulfide electrolyte combustion and cell explosion. This severely restricts the industrialization process of sulfide all-solid-state batteries in the fields of power batteries and energy storage batteries.

[0004] To mitigate the aforementioned thermal runaway problem, existing technologies primarily employ two approaches: one is to introduce other cations to construct a gradient diffusion layer, thereby enhancing the stability of oxygen in the cathode lattice and reducing oxygen release; the other is to construct a functional coating on the cathode surface to form an oxygen barrier. However, both elemental doping modification and cathode surface coating treatment have limited effectiveness in suppressing oxygen release from the cathode, failing to fundamentally block the contact reaction between sulfide electrolytes and oxygen, and thus making it difficult to completely resolve the potential for thermal runaway.

[0005] Furthermore, the poor air stability of sulfide electrolytes is another major technical bottleneck, further limiting their practical application. Sulfide electrolytes (such as Li3PS4 and Li6PS5Cl) contain thiophosphate (PS4) groups in their molecular structure. 3- ) and S in the structure of sulfide-germanium ore 2- It exhibits strong nucleophilicity and readily undergoes nucleophilic substitution reactions with water molecules in the air. When sulfide electrolytes are exposed to air, their surfaces rapidly adsorb trace amounts of moisture and form hydroxyl groups (-OH). The presence of these hydroxyl groups further accelerates the adsorption and diffusion of water molecules on the electrolyte surface, leading to hydrolysis and the generation of toxic H2S gas. Simultaneously, it damages the electrolyte's crystal structure, reduces its ionic conductivity, and consequently affects the cycle stability and lifespan of all-solid-state batteries, increasing safety risks and costs during battery manufacturing, storage, and use.

[0006] Therefore, developing a sulfide solid electrolyte material that combines excellent thermal stability in oxygen atmosphere with good hydrophobicity has become a key technical challenge that urgently needs to be solved in the current industrialization of sulfide all-solid-state batteries. It has important practical significance and industrial value for promoting the development of all-solid-state batteries towards high safety, high stability and long life, and accelerating their commercial application in power batteries, energy storage batteries and other fields. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a sulfide solid electrolyte material, its preparation method, and its application.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a sulfide solid electrolyte material, comprising a core and a coating layer covering the surface of the core; the core comprises a sulfide electrolyte; the coating layer comprises an organic-inorganic hybrid polymer; the structural formula of the organic-inorganic hybrid polymer is shown below: [-Si(R)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(R)2-] n ; Wherein, R is a fluoroalkyl group; and the value of n satisfies 300≤n≤10000.

[0009] The sulfide solid electrolyte material of this invention incorporates aluminum, silicon, boron, and fluorine elements through the molecular structure design of its surface coating layer. This forms an organic-inorganic hybrid polymer network with high-bond-energy BO, Si-O, and Al-O bonds as the main chain. In this molecular framework, the bond energies of the BO, Si-O, and Al-O bonds are significantly higher than those of the C-C bonds in traditional organic polymers, giving it excellent resistance to fracture and decomposition at high temperatures. This creates a thermochemically stable physical barrier on the surface of the sulfide electrolyte particles, effectively preventing direct contact between oxygen and water molecules and delaying or inhibiting the oxidation, hydrolysis, and thermal runaway reactions of sulfides under high-temperature conditions. Furthermore, by modifying the alkyl chains in the molecular chain with fluorine substitution, the surface energy of the sulfide solid electrolyte material is reduced, endowing it with intrinsic hydrophobic properties. This makes it difficult for water molecules to adsorb and penetrate the material surface, thus significantly improving the structural stability and hydrolysis resistance of the sulfide electrolyte in humid air. Furthermore, the coating layer of the sulfide solid electrolyte material of the present invention has low polarity and excellent electronic insulation properties, which can effectively block the local transport path of electrons from the electrode to the electrolyte, suppress electron leakage behavior, and avoid lithium dendrite nucleation and growth induced by local electron accumulation.

[0010] In a preferred embodiment of the sulfide solid electrolyte material of the present invention, R is a C1-C5 perfluoroalkyl group.

[0011] Preferably, R is trifluoromethyl or pentafluoroethyl.

[0012] In a preferred embodiment of the sulfide solid electrolyte material of the present invention, the value of n satisfies 500≤n≤2000.

[0013] Preferably, the value of n is a range of one or both of 500, 1000, 1500, and 2000.

[0014] In a preferred embodiment of the sulfide solid electrolyte material of the present invention, the average particle size of the core is 1μm-5μm.

[0015] In a preferred embodiment of the sulfide solid electrolyte material of the present invention, the thickness of the coating layer is 3nm-50nm.

[0016] Preferably, the thickness of the coating layer is 5nm-20nm.

[0017] In a preferred embodiment of the sulfide solid electrolyte material of the present invention, the chemical formula of the sulfide electrolyte is Li. a M b Pc S d X e Wherein, M includes at least one of Ge, Si, Sn, As, Sb, and B; X includes at least one of F, Cl, Br, I, and O; and the values ​​of a, b, c, d, and e satisfy 2≤a≤10, 0≤b≤2, 0≤c≤3, 4≤d≤12, and 0≤e≤1.75.

[0018] Preferably, the sulfide electrolyte is Li6PS5Cl or Li 5.5 PS 4.5 Cl 1.5 Li7P2S8I, Li7P3S 11 Li3PS4, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 10 GeP2S 12 Li 9.54 Ge 1.74 P 1.44 S 11.7 Cl 0.3 Li 6.3 Sn 0.3 As 0.7 S5I, Li 5.5 PS 4.5-x O x Cl 1.5 Li4GeS4, Li 20 / 3 (GeSiSb) 1 / 3 Any one of S5I, Li2S-B2S3-P2S5-LiI.

[0019] More preferably, the sulfide electrolyte is Li6PS5Cl or Li 5.5 PS 4.5 Cl 1.5 Any one of Li7P2S8I.

[0020] As a preferred embodiment of the sulfide solid electrolyte material of the present invention, the preparation method of the organic-inorganic hybrid polymer includes the following steps: (1) Dialkoxydi(fluoroalkyl)silane is hydrolyzed to obtain dihydroxydi(fluoroalkyl)silane; (2) Aluminum alkoxide and borate ester are mixed in an organic solvent to carry out a hydrolysis-condensation reaction to obtain a boron aluminum oxane prepolymer containing terminal hydroxyl groups; (3) The dihydroxydi(fluoroalkyl)silane and the boronaluminoxane prepolymer are mixed and subjected to polycondensation reaction to obtain the organic-inorganic hybrid polymer.

[0021] Preferably, in step (2), the aluminum alkoxide is aluminum isopropoxide; the borate ester is triisopropoxyboron; and the molar ratio of the aluminum alkoxide to the borate ester is 1:(1.5-2.5).

[0022] Preferably, in step (3), the polycondensation reaction is carried out in stages with increasing temperature. The first stage is carried out at 70℃-90℃ for 3-5 hours, and the second stage is carried out at 90℃-110℃ for 2-10 hours.

[0023] Secondly, the present invention provides a method for preparing the sulfide solid electrolyte material, comprising the following steps: S1. Dissolve the organic-inorganic hybrid polymer in a solvent to obtain a coating solution; S2. Add the sulfide electrolyte to the coating solution and mix to deposit the organic-inorganic hybrid polymer on the surface of the sulfide electrolyte; S3. Separate and dry the obtained solid to obtain the sulfide solid electrolyte material.

[0024] In a preferred embodiment of the preparation method of the sulfide solid electrolyte material of the present invention, the mass ratio of the organic-inorganic hybrid polymer to the sulfide electrolyte is (0.05-0.5):100.

[0025] In a preferred embodiment of the preparation method of the sulfide solid electrolyte material of the present invention, in step S1, the solvent includes at least one selected from anisole, n-butyl ether, dibutyl ether, isobutyl ether, diisopentyl ether, propyl butyl ether, isopentyl butyl ether, diethyl ether, and isopropyl ether; and / or, in step S2, the mixing temperature is 50℃-80℃ and the time is 1h-5h; and / or, in step S3, the drying temperature is 50℃-80℃ and the time is 5h-12h.

[0026] Preferably, in step S1, the solvent includes at least one of anisole, dibutyl ether, and n-butyl ether.

[0027] Preferably, in step S2, the mixing temperature is 50℃-60℃ and the mixing time is 1h-3h.

[0028] Preferably, in step S3, the drying temperature is 80°C and the time is 8 hours.

[0029] Thirdly, the present invention provides an all-solid-state lithium-ion battery, comprising a positive electrode layer, an electrolyte layer and a negative electrode layer, wherein at least one layer comprises the aforementioned sulfide solid electrolyte material.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: The BO, Si-O, and Al-O bond energies in the coating layer of the sulfide solid electrolyte material of the present invention are extremely high, enabling the material to maintain structural integrity and chemical inertness in air or oxygen atmospheres. Its upper limit of thermal stability temperature is significantly improved compared to uncoated sulfide solid electrolyte materials, effectively suppressing thermal runaway reactions between the electrolyte and highly active cathode materials, and broadening the material's process operation window and application scenarios. Secondly, the hydrophobic coating layer formed by fluorine substitution modification in the sulfide solid electrolyte material of the present invention reduces the surface energy of the coated material and significantly increases the contact angle, exhibiting intrinsic hydrophobic properties. This greatly reduces the material's tendency to absorb moisture and decompose in humid air, improves the stability of the electrolyte material during storage, transportation, and assembly under normal conditions, and reduces the stringent protection requirements during production and application. Furthermore, the coating layer of the sulfide solid electrolyte material of the present invention has excellent electronic insulation properties, which keeps the overall electronic conductivity of the material at an extremely low level. This effectively blocks the electron leakage path and inhibits the nucleation and penetration behavior of lithium dendrites, thereby significantly improving the cycle life and safety of the battery while maintaining acceptable ionic conductivity. Detailed Implementation

[0031] To better illustrate the objectives, technical solutions, and advantages of this invention, the invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0032] The following description, in conjunction with specific embodiments, illustrates the practical effects of the present invention.

[0033] Unless otherwise specified, the experimental methods used in the examples are conventional methods; the materials, reagents, equipment, etc. used are all commercially available unless otherwise specified.

[0034] The raw materials used in the following embodiments and comparative examples are described below, but are not limited to these materials: The preparation method of 3,3,3-trifluoromethyldimethoxysilane (CH3OSi(CF3)2OCH3) includes the following steps: (1) Under inert gas protection, add catalyst CsF (1.52g, CAS No.: 13400-13-0, purchased from Maclean's platform) and anhydrous THF (20mL, CAS No.: 109-99-9, purchased from Maclean's platform) to a 100mL Schlenk flask and stir at room temperature for 10min to activate the catalyst; slowly add (trifluoromethyltrimethylsilane 14.2g, CAS No.: 81290-20-2, purchased from Maclean's platform) dropwise using a constant pressure dropping funnel, keeping the system temperature at 20-25℃ during the dropwise addition. After the dropwise addition is complete, continue stirring for 30min. At this time, the solution is light yellow and transparent (active CF3 is generated). ⁻ Intermediate); then slowly add SiCl4 (8.5g, CAS:10026-04-7, purchased from Aladdin). There will be slight exothermic reaction during the drop addition, so the temperature needs to be controlled with a cold water bath ≤28℃. After the drop addition is complete, close the dropping funnel and stir the reaction at room temperature for 12h. After the reaction is complete, the solution is colorless and transparent. Distill off the low-boiling-point byproduct at 70℃ to obtain bis(trifluoromethyl)dichlorosilane ((CF3)2SiCl2).

[0035] (2) Under an inert atmosphere, anhydrous methanol (8.0 g, 250 mmol, CAS No.: 67-56-1, purchased from Aladdin) was added to a 250 mL Schlenk flask. The flask was cooled to 0 °C in an ice-water bath. Sodium methoxide (5.94 g, CAS No.: 124-41-4, purchased from Aladdin) was added in portions and stirred until completely dissolved to obtain a clear sodium methoxide methanol solution. The (CF3)2SiCl2 (9.5 g, 41 mmol) obtained in the first step was slowly added dropwise using a constant pressure dropping funnel. During the addition, the system temperature was kept at 0-5 °C and dry nitrogen gas was passed through the system to carry away the trace amount of HCl generated. After the addition was completed, the ice-water bath was removed and the temperature was naturally raised to 25 °C. The reaction was stirred for 2 h. After the reaction was completed, the NaCl precipitate was removed by filtration using a sintered glass funnel to obtain the target product 3,3,3-trifluoromethyldimethoxysilane (CH3OSi(CF3)2OCH3).

[0036] The preparation method of bis(pentafluoroethyl)dimethoxysilane (CH3OSi(C2F5)2OCH3) includes the following steps: (1) Under inert gas protection, anhydrous n-hexane (CAS No.: 110-54-3, purchased from Aladdin) and phenol (CAS No.: 108-95-2, purchased from Aladdin) were added to a 250 mL Schlenk flask and stirred until dissolved; the mixture was cooled to 0°C in an ice-water bath and triethylamine (CAS No.: 121-44-8, purchased from Aladdin) was slowly added dropwise. After the addition was completed, the mixture was stirred for 10 min and silicon tetrachloride was slowly added dropwise (as above). During the addition, the system temperature was kept ≤5°C. After the addition was completed, the mixture was naturally heated to room temperature and stirred for 4 h. The triethylamine hydrochloride precipitate was removed by filtration, and the n-hexane was removed by atmospheric distillation of the filtrate to obtain dichlorodiphenoxysilane (SiCl2(OC6H5)2).

[0037] (2) Under inert gas protection, 100 mL of anhydrous THF (CAS No.: 109-99-9, purchased from Maclean Platform) and 24.6 g of pentafluoroiodoethane (CAS No.: 354-64-3, purchased from Aladdin) were added to a 500 mL Schlenk flask. The mixture was cooled and stirred at -20 °C. A solution of n-butyllithium (2.5 mol / L hexane solution, 40 mL, CAS No.: 109-72-8, purchased from Inokai) was slowly added dropwise. After the addition was complete, the mixture was stirred for 30 min to generate a pale yellow pentafluoroethyl lithium solution. Anhydrous THF solution of dichlorodiphenoxysilane (13.2 g dissolved in 20 mL THF) was slowly added dropwise. The reaction was stopped after stirring for 12 h. The mixture was filtered and distilled under reduced pressure to obtain a colorless and transparent liquid, di(pentafluoroethyl)diphenoxysilane (C2F5)2Si(OC6H5)2.

[0038] (3) Under inert gas protection, 19.2 g of anhydrous methanol (CAS No.: 67-56-1, purchased from Aladdin) and 0.16 g of sodium methoxide (CAS No.: 124-41-4, purchased from Aladdin) were added to a 250 mL Schlenk flask and stirred until dissolved. Then, 14.0 g of di(pentafluoroethyl)diphenoxysilane was added, heated to 60 °C, and stirred for 6 h. During the reaction, the phenol-methanol azeotrope generated was continuously distilled off through a distillation column to promote complete reaction. After the reaction was completed, the mixture was cooled to room temperature to obtain di(pentafluoroethyl)dimethoxysilane (CH3OSi(C2F5)2OCH3).

[0039] Diethyldimethoxysilane (CH3OSi(C2H5)2OCH3), purchased from Hangzhou Kawei Chemical Technology Co., Ltd., CAS No. 15164-57-5; The Li7P2S8I, model number TS-I-003, was purchased from Tianshi Kefeng. Li6PS5Cl, purchased from Tianshi Kefeng, model number TS-C-001. Li 5.5 PS 4.5Cl 1.5 Purchased from Tianshi Kefeng, model number TS-GC-001.

[0040] The coating material used in the embodiments of the present invention is an organic-inorganic hybrid polymer, which, unless otherwise specified, is prepared by the polycondensation reaction of fluorinated silicon end groups and boron aluminum oxane prepolymer.

[0041] The specific preparation methods of the organic-inorganic hybrid polymers used in the following examples and comparative examples are described below: Organic-inorganic hybrid polymer 1: The repeating unit is [-Si(CF3)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(CF3)2-], with a degree of polymerization DPn≈500. Its preparation method includes the following steps: (1) Hydrolysis of fluorosilanes In a reaction vessel, 40 mmol of 3,3,3-trifluoromethyldimethoxysilane was dispersed in 100 mL of anhydrous toluene, and then a premix (80 mmol of deionized water + 0.4 mmol of concentrated hydrochloric acid (37%)) was added dropwise. The mixture was stirred continuously at 25 °C for 2 h, and then all solvents were removed by vacuum distillation at 50 °C to obtain di(trifluoromethyl)silanediol (HO-Si(CF3)2-OH).

[0042] The specific reaction formula is shown below: CH3OSi(CF3)2OCH3+2H2O→HO-Si(CF3)2-OH+2CH3OH (2) Synthesis of boron aluminum oxane prepolymer 20 mmol of aluminum isopropoxide and 200 mL of anhydrous toluene were added to a 1000 mL three-necked flask. The mixture was heated to 60 °C and stirred at 300 rpm until completely dissolved. Then, 40 mmol of triisopropoxyboron was slowly added dropwise at a rate of 0.5 mL / min. After the addition was complete, the mixture was kept at this temperature for 1 h to generate an aluminum-boron alkoxide complex. Next, a premixed solution (180 mmol of deionized water + 0.9 mmol of concentrated hydrochloric acid (37%)) was added dropwise. The mixture was heated to 75 °C and reacted for 2.5 h. The system changed from clear to a homogeneous slightly turbid liquid. The alkoxide was hydrolyzed to generate a boron aluminum oxane prepolymer ((OH)2B-O-Al(OH)-OB(OH)2) containing terminal -B(OH) and -Al(OH) groups. Finally, the solution was distilled under reduced pressure at a vacuum of 0.09 MPa below 80 °C to remove the byproduct isopropanol, yielding a toluene solution of boron aluminum oxane prepolymer with a solid content of 15 wt%.

[0043] The specific reaction formula is shown below: Al(OC3H7)3+3H2O→3C3H8O+Al(OH)3 B(OC3H7)3+3H2O→3C3H8O+B(OH)3 Al(OH)3+2B(OH)3→(OH)2B-O-Al(OH)-OB(OH)2+2H2O (3) Polycondensation reaction of fluorinated silanols with prepolymer Dissolve the bis(trifluoromethyl)silanediol from step (1) in 100 mL of anhydrous toluene, add the above boronaluminoxane prepolymer solution, and stir to mix evenly; then, control the reaction using a staged temperature increase program: First stage: Heat to 80℃ and react for 4 hours to initiate low-viscosity chain and generate short-chain oligomers; Second stage: Heat to 100℃ and react for 4 hours to carry out chain growth reaction, and obtain an organic-inorganic hybrid polymer with the target degree of polymerization (DPn≈500).

[0044] The specific reaction formula is shown below: n[(HO)2B-O-Al(OH)-OB(OH)2]+2n[HO-Si(CF3)2-OH]→[-Si(CF3)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(CF3)2-] n +2nH2O Organic-inorganic hybrid polymer 2: The repeating unit is [-Si(C2F5)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(C2F5)2-], with a degree of polymerization DPn≈500. Its preparation method differs from the aforementioned organic-inorganic hybrid polymer 1 only in that: Replace 3,3,3-trifluoromethyldimethoxysilane (CH3OSi(CF3)2OCH3) in step (1) with an equimolar amount of di(pentafluoroethyl)dimethoxysilane (CH3OSi(C2F5)2OCH3).

[0045] Organic-inorganic hybrid polymer 3: The repeating unit is [-Si(CF3)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(CF3)2-], with a degree of polymerization DPn≈2000. Its preparation method differs from the aforementioned organic-inorganic hybrid polymer 1 only in that: The reaction time for the second stage in step (3) is extended to 10 hours.

[0046] Organic-inorganic hybrid polymer 4: The repeating unit is [-Si(C2H5)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(C2H5)2-], with a degree of polymerization DPn≈500. Its preparation method differs from the aforementioned organic-inorganic hybrid polymer 1 only in that: Replace 3,3,3-trifluoromethyldimethoxysilane (CH3OSi(CF3)2OCH3) in step (1) with an equimolar amount of diethyldimethoxysilane (CH3OSi(C2H5)2OCH3).

[0047] Organic-inorganic hybrid polymer 5: The repeating unit is [-Si(C2F5)2-OB(OH)-O-Si(C2F5)2-], with a degree of polymerization DPn≈500. Its preparation method includes the following steps: (1) Hydrolysis of fluorosilanes In a reaction vessel, 40 mmol of di(pentafluoroethyl)dimethoxysilane (CH3OSi(C2F5)2OCH3) was dispersed in 100 mL of toluene, and a premix (80 mmol of deionized water + 0.4 mmol of concentrated hydrochloric acid (37%)) was added dropwise. The mixture was stirred continuously at 25 °C for 2 h, and all solvents were removed by vacuum distillation at 50 °C to obtain di(pentafluoroethyl)silanediol.

[0048] The specific reaction formula is shown below: CH3OSi(C2F5)2OCH3+2H2O→HO-Si(C2F5)2-OH+2CH3OH (2) Synthesis of boric acid prepolymer Add 40 mmol of triisopropoxyboron and 200 mL of toluene to a 1000 mL three-necked flask, heat to 60 °C and stir at 300 rpm until completely dissolved; then add the premixed solution (80 mmol of deionized water + 0.4 mmol of concentrated hydrochloric acid (37%)) dropwise, heat to 75 °C and react for 2.5 h to obtain boric acid prepolymer.

[0049] The specific reaction formula is shown below: B(OC3H7)3+3H2O→3C3H8O+B(OH)3 (3) Polycondensation reaction of fluorinated silanols with prepolymer Dissolve the di(pentafluoroethyl)silanediol from step (1) in 100 mL of toluene, add the above boric acid prepolymer solution, and stir to mix evenly; then, control the reaction using a staged temperature increase program: First stage: Heat to 80℃ and react for 4 hours to initiate low-viscosity chain and generate short-chain oligomers; Second stage: Heat to 100℃ and react for 4 hours to carry out chain growth reaction, and obtain an organic-inorganic hybrid polymer with the target degree of polymerization (DPn≈500).

[0050] The specific reaction formula is shown below: n[B(OH)3]+2n[HO-Si(C2F5)2-OH]→[-Si(C2F5)2-OB(OH)-O-Si(C2F5)2-] n +2nH2O Organic-inorganic hybrid polymer 6: The repeating unit is [-Si(C2F5)2-O-Al(OH)-O-Si(C2F5)2-], with a degree of polymerization DPn≈500. Its preparation method includes the following steps: (1) Hydrolysis of fluorosilanes In a reaction vessel, 40 mmol of di(pentafluoroethyl)dimethoxysilane (CH3OSi(C2F5)2OCH3) was dispersed in 100 mL of toluene. Then, a premix (80 mmol of deionized water + 0.4 mmol of concentrated hydrochloric acid (37%)) was added dropwise. The mixture was stirred continuously at 25 °C for 2 h. All solvents were removed by vacuum distillation at 50 °C to obtain di(pentafluoroethyl)silanediol.

[0051] The specific reaction formula is shown below: CH3OSi(C2F5)2OCH3+2H2O→HO-Si(C2F5)2-OH+2CH3OH (2) Synthesis of aluminum hydroxide prepolymer Add 20 mmol aluminum isopropoxide and 200 mL anhydrous toluene to a 1000 mL three-necked flask, heat to 60 °C and stir at 300 rpm until completely dissolved; then add the premixed solution (80 mmol deionized water + 0.4 mmol concentrated hydrochloric acid (37%)) dropwise, heat to 75 °C and react for 2.5 h to obtain aluminum hydroxide prepolymer.

[0052] The specific reaction formula is shown below: Al(OC3H7)3+3H2O→3C3H8O+Al(OH)3 (3) Polycondensation reaction of fluorinated silanols with prepolymer Dissolve the bis(pentafluoroethyl)silanediol from step (1) in 100 mL of anhydrous toluene, add the above prepolymer solution, and stir to mix evenly; then, control the reaction using a staged temperature increase program: First stage: Heat to 80℃ and react for 4 hours to initiate low-viscosity chain and generate short-chain oligomers; Second stage: Heat to 100℃ and react for 4 hours to carry out chain growth reaction, and obtain an organic-inorganic hybrid polymer with the target degree of polymerization (DPn≈500).

[0053] The specific reaction formula is shown below: n[Al(OH)3]+2n[HO-Si(C2F5)2-OH]→[-Si(C2F5)2-O-Al(OH)-O-Si(C2F5)2-] n +2nH2O The molecular weight of the prepared organic-inorganic hybrid polymer was determined by gel permeation chromatography (GPC). The specific testing method includes the following steps: First, take an organic-inorganic hybrid polymer sample, dissolve it in anisole to prepare a solution with a concentration of 0.2 mg / mL, let it stand to degas and remove impurities, and then use a series of standard polystyrene samples to plot a molecular weight-elution volume calibration curve; then, inject the sample solution to be tested into a gel permeation chromatograph for elution detection.

[0054] During data processing, the number-average molecular weight (Mn) and polydispersity index of the sample are calculated based on the elution curve and the calibration curve.

[0055] The specific test results are shown in Table 1: Table 1. GPC characterization data of coating materials - organic-inorganic hybrid polymers Example 1: This embodiment provides a sulfide solid electrolyte material having a core-shell structure, including a core and a coating layer covering the surface of the core; Core material: Li7P2S8I; Coating material: Organic-inorganic hybrid polymer 1, The repeating unit is [-Si(CF3)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(CF3)2-], and the degree of polymerization DPn≈500; Coating thickness: 5nm; The preparation method of the sulfide solid electrolyte material in this embodiment includes the following steps: S1. Dissolve 1.35g of organic-inorganic hybrid polymer 1 in 2000mL of anhydrous anisole to obtain a coating solution; S2. Add 1000g Li7P2S8I to the above coating solution, heat and stir at 60°C for 1 hour to uniformly deposit the coating material on the surface of the core particles. S3. Filter the mixture, collect the solid product, and vacuum dry it at 80°C for 8 hours to obtain the sulfide solid electrolyte material.

[0056] Example 2: This embodiment provides a sulfide solid electrolyte material having a core-shell structure, including a core and a coating layer covering the surface of the core; Core material: Li6PS5Cl; Coating material: Organic-inorganic hybrid polymer 1, The repeating unit is [-Si(CF3)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(CF3)2-], and the degree of polymerization DPn≈500; Coating thickness: 5nm; The preparation method of the sulfide solid electrolyte material in this embodiment includes the following steps: S1. Dissolve 1.26 g of organic-inorganic hybrid polymer 1 in 2000 mL of anhydrous anisole to obtain a coating solution; S2. Add 1000g Li6PS5Cl to the above coating solution, heat and stir at 50°C for 3 hours to make the coating material uniformly deposited on the surface of the core particles. S3. Filter the mixture, collect the solid product, and vacuum dry it at 80°C for 8 hours to obtain the sulfide solid electrolyte material.

[0057] Example 3: This embodiment provides a sulfide solid electrolyte material having a core-shell structure, including a core and a coating layer covering the surface of the core; Core material: Li6PS5Cl; Coating material: Organic-inorganic hybrid polymer 2, The repeating unit is [-Si(C2F5)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(C2F5)2-], and the degree of polymerization DPn≈500; Coating thickness: 5nm; The preparation method of the sulfide solid electrolyte material in this embodiment includes the following steps: S1. Dissolve 1.14 g of organic-inorganic hybrid polymer 2 in 2000 mL of anhydrous dibutyl ether to obtain a coating solution; S2. Add 1000g Li6PS5Cl to the above coating solution, heat and stir at 50°C for 3 hours to make the coating material uniformly deposited on the surface of the core particles. S3. Filter the mixture, collect the solid product, and vacuum dry it at 80°C for 8 hours to obtain the sulfide solid electrolyte material.

[0058] Example 4: This embodiment provides a sulfide solid electrolyte material having a core-shell structure, including a core and a coating layer covering the surface of the core; Core material: Li6PS5Cl; Coating material: Organic-inorganic hybrid polymer 1, The repeating unit is [-Si(CF3)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(CF3)2-], and the degree of polymerization DPn≈500; Coating thickness: 3nm; The preparation method of the sulfide solid electrolyte material in this embodiment includes the following steps: S1. Dissolve 0.92 g of organic-inorganic hybrid polymer 1 in 2000 mL of anhydrous n-butyl ether to obtain a coating solution; S2. Add 1000g Li6PS5Cl to the above coating solution and heat and stir at 60°C for 2 hours to make the coating material uniformly deposited on the surface of the core particles. S3. Filter the mixture, collect the solid product, and vacuum dry it at 80°C for 8 hours to obtain the sulfide solid electrolyte material.

[0059] Example 5: This embodiment provides a sulfide solid electrolyte material having a core-shell structure, including a core and a coating layer covering the surface of the core; Core material: Li 5.5 PS 4.5 Cl 1.5 ; Coating material: Organic-inorganic hybrid polymer 3, The repeating unit is [-Si(CF3)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(CF3)2-], and the degree of polymerization DPn≈2000; Coating thickness: 20nm; The preparation method of the sulfide solid electrolyte material in this embodiment includes the following steps: S1. Dissolve 4.38 g of organic-inorganic hybrid polymer 3 in 2000 mL of anhydrous n-butyl ether to obtain a coating solution; S2. Add 1000g Li to the above coating solution. 5.5 PS 4.5 Cl 1.5 Heating and stirring at 60℃ for 2 hours allows the coating material to be uniformly deposited on the surface of the core particles. S3. Filter the mixture, collect the solid product, and vacuum dry it at 80°C for 8 hours to obtain the sulfide solid electrolyte material.

[0060] Example 6: This embodiment provides a sulfide solid electrolyte material having a core-shell structure, including a core and a coating layer covering the surface of the core; Core material: Li 5.5 PS 4.5 Cl 1.5 ; Coating material: Organic-inorganic hybrid polymer 2, The repeating unit is [-Si(C2F5)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(C2F5)2-], and the degree of polymerization DPn≈500; Coating thickness: 5nm; The preparation method of the sulfide solid electrolyte material in this embodiment includes the following steps: S1. Dissolve 1.53g of organic-inorganic hybrid polymer 2 in 2000mL of anhydrous n-butyl ether to obtain a coating solution; S2. Add 1000g Li to the above coating solution. 5.5 PS 4.5 Cl 1.5 Heating and stirring at 60℃ for 2 hours allows the coating material to be uniformly deposited on the surface of the core particles. S3. Filter the mixture, collect the solid product, and vacuum dry it at 80°C for 8 hours to obtain the sulfide solid electrolyte material.

[0061] Example 7: This embodiment provides a sulfide solid electrolyte material having a core-shell structure, including a core and a coating layer covering the surface of the core; Core material: Li 5.5 PS 4.5 Cl 1.5 ; Coating material: Organic-inorganic hybrid polymer 3, The repeating unit is [-Si(CF3)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(CF3)2-], and the degree of polymerization DPn≈2000; Coating thickness: 20nm; The preparation method of the sulfide solid electrolyte material in this embodiment includes the following steps: S1. Dissolve 4.38g of organic-inorganic hybrid polymer 3 in 2000mL of anhydrous anisole to obtain a coating solution; S2. Add 1000g Li to the above coating solution. 5.5 PS 4.5 Cl 1.5Heating and stirring at 60℃ for 2 hours allows the coating material to be uniformly deposited on the surface of the core particles. S3. Filter the mixture, collect the solid product, and vacuum dry it at 80°C for 8 hours to obtain the sulfide solid electrolyte material.

[0062] Comparative Example 1: This comparative example provides a sulfide solid electrolyte material, which uses Li7P2S8I directly as a control sample without surface treatment.

[0063] Comparative Example 2: This comparative example provides a sulfide solid electrolyte material, which is used directly as a control sample without surface treatment, using Li6PS5Cl directly.

[0064] Comparative Example 3: This comparative example provides a sulfide solid electrolyte material that uses Li directly without surface treatment. 5.5 PS 4.5 Cl 1.5 As a control sample.

[0065] Comparative Example 4: This comparative example provides a sulfide solid electrolyte material having a core-shell structure, including a core and a coating layer covering the surface of the core; Core material: Li 5.5 PS 4.5 Cl 1.5 ; Coating material: Organic-inorganic hybrid polymer 4, The repeating unit is [-Si(C2H5)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(C2H5)2-], and the degree of polymerization DPn≈500; Coating thickness: 5nm; The preparation method of this comparative sulfide solid electrolyte material is as described in Example 5.

[0066] Comparative Example 5: This comparative example provides a sulfide solid electrolyte material having a core-shell structure, including a core and a coating layer covering the surface of the core; Core material: Li 5.5 PS 4.5 Cl 1.5 ; Coating material: Organic-inorganic hybrid polymer 5, The repeating unit is [-Si(C2F5)2-OB(OH)-O-Si(C2F5)2-], and the degree of polymerization DPn≈500; Coating thickness: 5nm; The preparation method of this comparative sulfide solid electrolyte material is as described in Example 5.

[0067] Comparative Example 6: This comparative example provides a sulfide solid electrolyte material having a core-shell structure, including a core and a coating layer covering the surface of the core; Core material: Li 5.5 PS 4.5 Cl 1.5 ; Coating material: Organic-inorganic hybrid polymer 6, The repeating unit is [-Si(C2F5)2-O-Al(OH)-O-Si(C2F5)2-], and the degree of polymerization DPn≈500; Coating thickness: 5nm; The preparation method of this comparative sulfide solid electrolyte material is as described in Example 5.

[0068] Test example: This test example performs the following performance tests on the sulfide solid electrolyte materials prepared in the above embodiments and comparative examples: 1.1 Ionic conductivity and electronic conductivity testing Test method: In an inert atmosphere glove box, 100 mg of the sulfide solid electrolyte material to be tested was weighed, pressed into shape under a pressure of 300 MPa, and then a carbon sheet was used as a blocking electrode. The test was carried out using an electrochemical workstation (Autolab) under a constant temperature of 25℃.

[0069] Ionic conductivity (σ) = L / (R×S); Where L is the thickness of the electrolyte sheet (cm), R is the impedance (Ω), and S is the effective contact area between the electrode and the electrolyte (cm²). 2 ).

[0070] 2.2 Air stability test Test method: The ionic conductivity of the sulfide solid electrolyte material under test is tested by comparing the retention rate of ionic conductivity before and after air exposure. Specifically, firstly, the initial ionic conductivity of the sample is tested according to the above-mentioned ionic conductivity test method; then, the sample is directly exposed to dry air with a dew point of -40℃ for 8 hours, the exposed sample is recovered, and its ionic conductivity is tested again.

[0071] Conductivity retention rate (%) = (Conductivity after exposure / Conductivity before exposure) × 100%.

[0072] 3.3 Electrochemical Cyclic Performance Test Test method: The sulfide solid electrolyte material to be tested is used as the solid electrolyte layer; the positive electrode is made of uncoated sulfide solid electrolyte (Li7P2S8I, Li6PS5Cl or Li 5.5 PS 4.5 Cl 1.5 The high-nickel ternary cathode material (NCM811), vapor-grown carbon fiber (VGCF), and polytetrafluoroethylene (PTFE) are mixed in a mass ratio of 12:85:2:1, rolled into a film, and die-cut. Using lithium metal as the negative electrode, a segmented stacking process is adopted to cut the positive electrode, solid electrolyte layer, and negative electrode and stack them sequentially to form an all-solid-state battery.

[0073] Charge and discharge tests were conducted at 25°C using a BTS-5V10mA battery test cabinet: the first cycle was activated at 0.1C, followed by 300 cycles of constant current charge and discharge at a current density of 0.3C, and the capacity retention rate was recorded on the 300th cycle.

[0074] 4. High-temperature stability test Test method: In an inert atmosphere glove box, the sulfide solid electrolyte material to be tested is mixed with fully charged NCM811 powder at a mass ratio of 1:2. Then, the mixture is poured into a mold with a diameter of 5 mm and pressed into a sheet using a tablet press under a pressure of 600 MPa. During the test, the positive electrode sheet is tightly attached to the heating plate and heated at a rate of 10 °C / min. The temperature at which the sample begins to burn is recorded.

[0075] The higher the initial combustion temperature, the better the high-temperature stability of the material.

[0076] 5. Contact Angle Test Test method: The sulfide solid electrolyte material to be tested is pressed into a dense disc with a diameter of 10mm-15mm and a thickness of 1mm-2mm. After cleaning the surface, it is vacuum dried at 60℃ for 2h. Then, the disc is transferred to a calibrated contact angle measuring instrument in an argon glove box with a dew point of <-60℃ and O2 <0.1ppm. At 25±2℃, 2μL of ultrapure water is dropped onto the sample surface with a microsyringe. After standing for 10s, the image is captured and the contact angle is calculated by software.

[0077] Each sample was measured 5 times at different locations, and the average value was taken.

[0078] Table 2. Performance test results of the sulfide solid electrolyte materials prepared in the examples and comparative examples. As can be seen from the test results in Table 2, the sulfide solid electrolyte material of this invention achieves significant improvements in ionic conductivity retention, electron blocking capability, air stability, high-temperature stability, electrochemical cycling performance, and hydrophobicity, demonstrating excellent comprehensive performance advantages. Specifically, firstly, although the ionic conductivity of the sulfide solid electrolyte material modified by the coating layer of this invention decreases slightly, its electronic conductivity is significantly reduced (as low as 10). -10 The capacity retention rate after 300 cycles is significantly higher than that of the unmodified sulfide solid electrolyte material (with a capacity of S / cm or less), indicating that the coating layer of the present invention can effectively suppress lithium dendrite growth, thereby significantly improving the long-cycle stability of the battery. Secondly, the starting combustion temperature of the sulfide solid electrolyte material in the embodiments of the present invention is significantly increased, and the starting combustion temperature further increases with the increase of coating layer thickness and polymer polymerization degree. This is attributed to the excellent thermal stability and physical isolation effect provided by the high bond energy network structure of BO, Si-O, and Al-O in the coating layer, which can effectively suppress the thermal runaway reaction pathway between the sulfide electrolyte and the highly active cathode material. Furthermore, the contact angles of the sulfide solid electrolyte materials in the embodiments of the present invention are significantly increased (>90°), exhibiting excellent hydrophobic properties. In contrast, the contact angles of the unmodified sulfide solid electrolyte materials are all less than 80°, exhibiting hydrophilicity. Moreover, after 8 hours of air exposure, the ionic conductivity retention rate of the sulfide solid electrolyte materials in the embodiments of the present invention is also much higher than that of the comparative example. This indicates that the introduction of fluorinated alkyl chains in the coating layer effectively increases and reduces the surface energy of the material, inhibits water adsorption and hydrolysis reactions, and enhances the material's resistance to hydrolysis. Furthermore, the sulfide solid electrolyte material of the present invention forms a rigid inorganic-organic hybrid network through BO-Al bridging bonds, thereby endowing the coating layer with high bond energy, high thermal stability and physical barrier ability. When the coating layer contains B, Al and F elements simultaneously, the material exhibits the best comprehensive performance in terms of cycle stability and high temperature stability. If Al element is missing, the BO-Al bridging network will be interrupted, resulting in a decrease in the thermal stability and mechanical density of the coating layer, and it will be unable to effectively isolate the transfer of oxygen and heat. If B element is missing, it will not only weaken the thermal stability of the BO-Al network, but also cause the passivation effect of B(OH)3 unit on lithium dendrites to be lost, thereby significantly reducing the high temperature resistance and interface stability of the material.

[0079] In summary, the fluorinated silicon-boron-aluminoxane core-shell structured sulfide solid electrolyte material of the present invention, through the design and synthesis of a polymer coating layer with a specific B-Al-O main chain and fluorinated silicon end groups, surface modification of the sulfide solid electrolyte, successfully achieves a synergistic balance between low electronic conductivity, high ionic conductivity retention, excellent high-temperature stability, and outstanding cycle performance. This effectively overcomes key challenges in the prior art, such as poor air stability, high-temperature instability, and poor interface compatibility with lithium metal anodes, significantly improving the overall electrochemical performance and safety reliability of all-solid-state batteries.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A sulfide solid electrolyte material, characterized in that, It includes a core and a coating layer covering the surface of the core; the core includes a sulfide electrolyte; the coating layer includes an organic-inorganic hybrid polymer; the structural formula of the organic-inorganic hybrid polymer is shown below: [-Si(R)2-OB(OH)-O-Al(OH)-OB(OH)-O-Si(R)2-] n ; Wherein, R is a fluoroalkyl group; and the value of n satisfies 300≤n≤10000.

2. The sulfide solid electrolyte material as described in claim 1, characterized in that, R is a C1-C5 perfluoroalkyl group.

3. The sulfide solid electrolyte material as described in claim 1, characterized in that, The value of n satisfies 500≤n≤2000.

4. The sulfide solid electrolyte material as described in claim 1, characterized in that, The thickness of the coating layer is 3nm-50nm.

5. The sulfide solid electrolyte material as described in claim 1, characterized in that, The chemical formula of the sulfide electrolyte is Li a M b P c S d X e Wherein, M includes at least one of Ge, Si, Sn, As, Sb, and B; X includes at least one of F, Cl, Br, I, and O; and the values ​​of a, b, c, d, and e satisfy 2≤a≤10, 0≤b≤2, 0≤c≤3, 4≤d≤12, and 0≤e≤1.

75.

6. The sulfide solid electrolyte material as described in claim 5, characterized in that, The sulfide electrolyte is Li6PS5Cl, Li 5.5 PS 4.5 Cl 1.5 Li7P2S8I, Li7P3S 11 Li3PS4, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 10 GeP2S 12 Li 9.54 Ge 1.74 P 1.44 S 11.7 Cl 0.3 Li 6.3 Sn 0.3 As 0.7 S5I, Li 5.5 PS 4.5-x O x Cl 1.5 Li4GeS4, Li 20 / 3 (GeSiSb) 1 / Any one of 3S5I, Li2S-B2S3-P2S5-LiI.

7. A method for preparing the sulfide solid electrolyte material according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Dissolve the organic-inorganic hybrid polymer in a solvent to obtain a coating solution; S2. Add the sulfide electrolyte to the coating solution and mix to deposit the organic-inorganic hybrid polymer on the surface of the sulfide electrolyte; S3. Separate and dry the obtained solid to obtain the sulfide solid electrolyte material.

8. The method for preparing the sulfide solid electrolyte material as described in claim 7, characterized in that, The mass ratio of the organic-inorganic hybrid polymer to the sulfide electrolyte is (0.05-0.5):

100.

9. The method for preparing the sulfide solid electrolyte material as described in claim 7, characterized in that, In step S1, the solvent includes at least one of anisole, n-butyl ether, dibutyl ether, isobutyl ether, diisopentyl ether, propyl butyl ether, isopentyl butyl ether, diethyl ether, and isopropyl ether; and / or, in step S2, the mixing temperature is 50℃-80℃ and the time is 1h-5h; and / or, in step S3, the drying temperature is 50℃-80℃ and the time is 5h-12h.

10. An all-solid-state lithium-ion battery, comprising a positive electrode layer, an electrolyte layer, and a negative electrode layer, characterized in that, At least one layer comprises the sulfide solid electrolyte material as described in any one of claims 1-6.

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