High-entropy halogen-site-doped sulfide solid electrolyte, and preparation method and application thereof

Abstract

This invention belongs to the field of solid electrolyte technology, and particularly relates to a high-entropy halogen-site doped sulfide solid electrolyte, its preparation method, and its application. The molecular formula of the high-entropy halogen-site doped sulfide solid electrolyte is: Li 6‑x PS 5‑x [(F y O 1‑y ) α (Cl y S 1‑y ) β (Br y Se 1‑y ) γ (I y Te 1‑y ) δ ] 1+x , 0.4≤x≤0.7, 0.5≤y≤1, α+β+γ+δ=1, 0≤α≤0.1, 0<β≤1, 0<δ<0.144, α+δ<0.2; This invention, by simultaneously doping at least two of the elements F, O, S, Br, Se, I, and Te at the Cl site, combined with the basic principles of high-entropy material design, regulates the proportions of F, O, Cl, S, Br, Se, I, and Te, while optimizing the electrolyte ion transport channels, crystal structure stability, and electrolyte / lithium metal interface reaction layer composition. This achieves the goal of significantly improving the stability of the electrolyte to air, solvents, and lithium metal while optimizing the room temperature ionic conductivity, thus overcoming the shortcomings of existing technologies.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolyte materials technology, and particularly relates to a high-entropy halogen-doped sulfide solid electrolyte, its preparation method and application. Background Technology

[0002] All-solid-state lithium-ion batteries are considered one of the core development directions for next-generation lithium-ion batteries due to their higher energy density, better safety, and longer cycle life. Solid-state electrolytes, as a key component of all-solid-state lithium-ion batteries, directly determine the overall performance of the battery. Among them, sulfide solid-state electrolytes, with their high room-temperature ionic conductivity, good machinability, and compatibility with electrode materials, have become a hot research topic.

[0003] Chlorine-rich system sulfide electrolyte Li 6-x PS 5-x Cl 1+x (0 < x < 1) is an important type of sulfide electrolyte. This system electrolyte has excellent room temperature ionic conductivity, which can meet the basic ion transport requirements of all-solid-state lithium-ion batteries and has broad application prospects in the field of all-solid-state batteries. However, this chlorine-rich electrolyte system has the problem of insufficient chemical / electrochemical stability: (1) poor stability to air and solvents. According to the soft and hard acid-base theory, PS4 3- The structural center P is a hard acid. Compared to the soft acid S, it reacts more readily with hard acid O in a humid environment, producing toxic H2S gas through attack. Simultaneously, when in contact with organic solvents, the P-S bond is weak, and the S-O bond... 2- Strong reducing properties, P 5+ / Li + Due to strong coordination with hard base solvents, sulfide solid electrolytes are prone to coordination, nucleophilicity, hydrolysis, and redox reactions with organic solvents, leading to electrolyte framework disintegration, loss of conductivity, structural pulverization, and carbonization residues. (2) The stability of the lithium metal anode is poor. Sulfide solid electrolytes are thermodynamically unstable with lithium metal. When in direct contact with lithium metal, they are prone to violent interfacial reactions, leading to electrolyte decomposition and the formation of an unstable interfacial reaction layer, which in turn increases the battery interfacial impedance. At the same time, the conductive interfacial reaction layer is prone to uneven lithium ion deposition during battery cycling, forming lithium dendrites at the interface, leading to battery short circuit failure.

[0004] In existing technologies, to address the poor stability of sulfide electrolytes to air and organic solvents, methods such as bulk doping and surface coating modification are mainly employed. The bulk doping approach is primarily based on the hard and soft acid-base theory, utilizing PS4... 3- Substitution of elements at the P and S sites in the group increases the strength of the PS bond and decreases the PS4 bond strength. 3-Group reactivity. However, doping and substitution of these framework elements often cause a certain degree of structural distortion. While optimizing stability to air and solvents, room temperature ionic conductivity is sacrificed, making it impossible to simultaneously optimize the stability of metallic lithium. Maintaining the framework structure PS4 3- By keeping the functional groups unchanged and optimizing their coordination environment, it is possible to adjust the composition of the interfacial reaction layer while modifying the crystal structure of the electrolyte, thereby simultaneously improving the room temperature ionic conductivity and chemical / electrochemical stability of the electrolyte. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies in Li 6-x PS 5-x Cl 1+x (0 < x < 1) To address the shortcomings of poor chemical / electrochemical stability of sulfide solid electrolytes, a high-entropy halogen-doped sulfide solid electrolyte, its preparation method, and its application are provided. The high-entropy halogen-doped sulfide solid electrolyte ensures high ionic conductivity while also exhibiting excellent stability against air, organic solvents, and lithium. Furthermore, the assembled all-solid-state battery demonstrates excellent cycle stability.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A high-entropy halogen-site doped sulfide solid electrolyte, wherein the sulfide solid electrolyte has the general chemical formula Li. 6- x PS 5-x [(F y O 1-y ) α (Cl y S 1-y ) β (Br y Se 1-y ) γ (I y Te 1-y ) δ ] 1+x Wherein, 0.4≤x≤0.7, 0.5≤y≤1, α+β+γ+δ=1, 0≤α≤0.1, 0<β≤1, 0<δ<0.144, α+δ<0.2; this sulfide solid electrolyte possesses both high room temperature ionic conductivity and high stability in air, solvents, and metallic lithium, with a room temperature ionic conductivity of 1×10 -2 S / cm ~ 5×10 -2 S / cm.

[0007] This invention also provides a method for preparing a high-entropy halogen-site doped sulfide solid electrolyte, specifically including the following steps: S1. According to the general formula Li 6-x PS 5-x [(Fy O 1-y ) α (Cl y S 1-y ) β (Br y Se 1-y ) γ (I y Te 1-y ) δ ] 1+x The precursor powder was obtained by physically mixing lithium source, phosphorus source, sulfur source, fluorine source, oxygen source, chlorine source, bromine source, selenium source, tellurium source and iodine source in stoichiometric ratios. S2. The precursor powder is calcined at high temperature in an inert atmosphere or vacuum and then naturally cooled to room temperature to obtain the high-entropy halogen-doped sulfide solid electrolyte.

[0008] Preferably, in step 1), the purity of the lithium source, phosphorus source, sulfur source, fluorine source, oxygen source, chlorine source, bromine source, selenium source, tellurium source and iodine source is not less than 99%, and the water content is less than 10 ppm.

[0009] Preferably, in step 1), the physical mixing method is high-energy ball milling, mechanical stirring, mechanical oscillation or roller milling, and the mixing time is 0.5 to 48 hours.

[0010] Preferably, in step 2), the conditions for high-temperature calcination are: in an inert atmosphere or in a vacuum, at 500–600°C for 0.5–24 hours.

[0011] Preferably, in step 2), the material that has been calcined and naturally cooled to room temperature is pulverized and ground to obtain the high-entropy halogen-doped sulfide solid electrolyte.

[0012] Another object of the present invention is to provide an application of the above-mentioned high-entropy halogen-doped sulfide solid electrolyte, which is used in all-solid-state lithium secondary batteries and in symmetrical batteries with metallic lithium as the symmetrical electrode.

[0013] Mechanism: This invention is based on the design principles of high-entropy materials. Its core is to improve the structural stability and overall performance of materials through the rational combination of multiple components and the synergistic effect between elements; due to the presence of halogen sites in Li... 6- x PS 5-x Cl 1+x (0 < x < 1) The electrolyte contains PS4, a non-framework group. 3-The construction utilizes the gradient differences in atomic size among different halogen elements (F, O, Cl, S, Br, Se, I, Te). By rationally controlling the composition and proportion of halogen elements, the atomic size mismatch can be kept within a reasonable range, thus forming a stable solid solution structure. Simultaneously, the framework group PS4 can be adjusted. 3- The coordination environment improves the ionic conductivity of sulfide solid electrolytes and their stability to air, organic solvents, and lithium metal.

[0014] The advantages of this invention are as follows: By simultaneously doping the Cl site with at least two of the elements F, O, S, Br, Se, I, and Te, and combining this with the basic principles of high-entropy material design, the proportions of various elements are controlled. Simultaneously, the electrolyte ion transport channels, crystal structure stability, and electrolyte / lithium metal interface reaction layer composition are optimized. This achieves a significant improvement in the stability of the electrolyte to air, solvents, and lithium metal while optimizing its room-temperature ionic conductivity. Furthermore, this invention employs a preparation method of raw material blending followed by a single-step calcination, resulting in a simplified and controllable process that significantly reduces the difficulty of preparation management and production costs, facilitating large-scale mass production. Detailed Implementation Example 1

[0015] Li₂S, P₂S₅, LiCl, LiBr, and LiI, each with a purity of ≥99%, were weighed according to stoichiometry and placed in an agate mortar. After grinding for 30 minutes under conditions where the water content was less than 10 ppm, Li₂S was obtained. 5.5 PS 4.5 Cl 0.7 Br 0.7 I 0.1 Precursor powder; The precursor powder was sintered in a muffle furnace under an inert atmosphere (argon) at a heating rate of 4°C / min to 500°C for 4 hours. After natural cooling to room temperature, the powder was ground uniformly to obtain Li. 5.5 PS 4.5 Cl 0.7 Br 0.7 I 0.1 Sulfide solid electrolyte.

[0016] Performance testing and battery assembly Grind Li 5.5 PS 4.5 Cl 0.7 Br 0.7 I 0.1 The sulfide solid electrolyte powder was pressed into tablets, and its room temperature ionic conductivity was measured to be 11.7 mS / cm. -1After exposure to dew point temperatures of -60℃, -50℃, and -40℃ in a dry room for 60 minutes, the room temperature conductivity was measured to be 11.31 mS / cm. -1 10.67 mS cm -1 10.49 mS cm -1 The retention rates were 96.7%, 91.2%, and 89.7%, respectively; after treatment with toluene, butyl butyrate, diethyl ether, acetonitrile, and tetrahydrofuran, the room temperature ionic conductivity was 10.97 mS / cm. -1 10.31 mS cm -1 10.05 mS cm -1 9.7 mS cm -1 9.35 mS cm -1 The retention rates were 93.8%, 88.1%, 85.9%, 82.9%, and 79.9%, respectively. Using lithium metal as the symmetrical electrode, Li 5.5 PS 4.5 Cl 0.7 Br 0.7 I 0.1 A sulfide solid electrolyte was used as the electrolyte layer, and a symmetrical cell was assembled. Cyclic testing was performed using the Blue Electric CT2001A battery testing system. The cell operated at a current density of 0.5 mA cm⁻¹. -2 It can be stably cycled for 5600 hours; Li 5.5 PS 4.5 Cl 0.7 Br 0.7 I 0.1 A sulfide solid electrolyte, a LiCoO2 cathode, and a lithium metal anode were assembled into an all-solid-state battery. The battery's electrochemical performance was tested using the Blue Electric CT2001A battery testing system. The charge-discharge voltage range was 3.0~4.2 V, the rate was 1C, and constant rate charge-discharge was performed. After 500 cycles, the capacity retention rate was 87.8%. Example 2

[0017] Li₂S, P₂S₅, LiCl, LiBr, and LiI, each with a purity of ≥99%, were weighed according to stoichiometry and placed in an agate mortar. After grinding for 30 minutes under conditions where the water content was less than 10 ppm, Li₂S was obtained. 5.4 PS 4.4 Cl 0.8 Br 0.7 I 0.1 Precursor powder; The precursor powder was sintered in a muffle furnace under an inert atmosphere (argon) at a heating rate of 4°C / min to 490°C for 4 hours. After natural cooling to room temperature, the powder was ground uniformly to obtain Li. 5.4 PS 4.4 Cl 0.8 Br 0.7 I 0.1 Sulfide solid electrolytes; Performance testing and battery assembly Grind Li 5.4 PS 4.4 Cl 0.8 Br 0.7 I 0.1 The sulfide solid electrolyte powder was pressed into tablets, and its room temperature ionic conductivity was measured to be 12.5 mS / cm. -1 After exposure to dew point temperatures of -60℃, -50℃, and -40℃ in a dry room for 60 minutes, the room temperature conductivity was measured to be 12.28 mS / cm. -1 11.9 mS cm -1 11.54 mS cm -1 The retention rates were 98.2%, 95.2%, and 92.3%, respectively; after treatment with toluene, butyl butyrate, diethyl ether, acetonitrile, and tetrahydrofuran, the room temperature ionic conductivity was 11.91 mS / cm. -1 11.51 mS cm -1 11.06 mS cm -1 10.68 mS cm -1 10.3 mS cm -1 The retention rates were 95.3%, 92.1%, 88.5%, 85.4%, and 82.4%, respectively. Using lithium metal as the symmetrical electrode, Li 5.4 PS 4.4 Cl 0.8 Br 0.7 I 0.1 A sulfide solid electrolyte was used as the electrolyte layer, and a symmetrical cell was assembled. Cyclic testing was performed using the Blue Electric CT2001A battery testing system. The cell operated at a current density of 0.5 mA cm⁻¹. -2 It can be stably cycled for 6000 hours; Li 5.4 PS 4.4 Cl 0.8 Br 0.7 I 0.1A sulfide solid electrolyte, a LiCoO2 cathode, and a lithium metal anode were assembled into an all-solid-state battery. The battery's electrochemical performance was tested using the Blue Electric CT2001A battery testing system. The charge-discharge voltage range was 3.0~4.2 V, the rate was 1C, and constant rate charge-discharge was performed. After 500 cycles, the capacity retention rate was 92.7%. Example 3

[0018] Li₂S, P₂S₅, PCl₅, LiBr, Se, and LiI, each with a purity of ≥99%, were weighed according to stoichiometry and placed in an agate mortar. After grinding for 30 minutes under conditions where the water content was less than 10 ppm, Li₂S was obtained. 5.6 PS 4.6 Cl 0.8 Br 0.3 Se 0.1 I 0.2 Precursor powder; The precursor powder was sintered in a muffle furnace under an inert atmosphere (argon) at a heating rate of 4°C / min to 510°C for 4 hours. After natural cooling to room temperature, the powder was ground uniformly to obtain Li. 5.6 PS 4.6 Cl 0.8 Br 0.3 Se 0.1 I 0.2 Sulfide solid electrolytes; Performance testing and battery assembly Grind Li 5.6 PS 4.6 Cl 0.8 Br 0.3 Se 0.1 I 0.2 The sulfide solid electrolyte powder was pressed into tablets, and its room temperature ionic conductivity was measured to be 14.3 mS / cm. -1 After exposure to dew point temperatures of -60℃, -50℃, and -40℃ in a dry room for 60 minutes, the room temperature conductivity was measured to be 13.63 mS / cm. -1 13.31 mS cm -1 12.9 mS cm -1 The retention rates were 95.3%, 93.1%, and 90.2%, respectively; after treatment with toluene, butyl butyrate, diethyl ether, acetonitrile, and tetrahydrofuran, the room temperature ionic conductivity was 13.21 mS / cm. -1 12.87 mS cm -1 12.36 mS cm -1 11.93 mS cm -1 11.50 mS cm -1The retention rates were 92.4%, 90%, 86.4%, 83.4%, and 80.4%, respectively. Using lithium metal as the symmetrical electrode, Li 5.6 PS 4.6 Cl 0.8 Br 0.3 Se 0.1 I 0.2 A sulfide solid electrolyte was used as the electrolyte layer, and the cells were assembled into a symmetrical battery. Cyclic testing was performed using the Blue Electric CT2001A battery testing system. The battery was tested at a current density of 0.5 mAcm⁻¹. -2 It can be stably cycled for 10,000 hours; Li 5.6 PS 4.6 Cl 0.8 Br 0.3 Se 0.1 I 0.2 A sulfide solid electrolyte, a LiCoO2 cathode, and a lithium metal anode were assembled into an all-solid-state battery. The battery's electrochemical performance was tested using the Blue Electric CT2001A battery testing system. The charge-discharge voltage range was 3.0~4.2 V, the rate was 1C, and constant rate charge-discharge was performed. After 500 cycles, the capacity retention rate was 90.5%. Example 4

[0019] Under an argon atmosphere, Li₂S, P₂S₅, S, LiCl, PBr₃, and LiI, each with a purity of ≥99%, were weighed according to stoichiometric ratio and placed in an agate mortar. After grinding for 30 minutes with a water content of less than 10 ppm, Li₂S was obtained. 5.3 PS 4.3 Cl 0.7 Br 0.76 I 0.24 Precursor powder; The precursor powder was sintered in a muffle furnace under an inert atmosphere (argon) at a heating rate of 4°C / min to 480°C for 4 hours. After natural cooling to room temperature, the powder was ground uniformly to obtain Li. 5.3 PS 4.3 Cl 0.7 Br 0.76 I 0.24 Sulfide solid electrolytes; Performance testing and battery assembly Grind Li 5.3 PS 4.3 Cl 0.7 Br 0.76 I 0.24 The sulfide solid electrolyte powder was pressed into tablets, and its room temperature ionic conductivity was measured to be 10.7 mS / cm. -1After exposure to dew point temperatures of -60℃, -50℃, and -40℃ in a dry room for 60 minutes, the room temperature conductivity was measured to be 10.54 mS / cm. -1 10.19 mS cm -1 9.92 mS cm -1 The retention rates were 98.5%, 95.2%, and 92.7%, respectively; after treatment with toluene, butyl butyrate, diethyl ether, acetonitrile, and tetrahydrofuran, the room temperature ionic conductivity was 10.23 mS / cm. -1 9.85 mS cm -1 9.51 mS cm -1 9.18 mS cm -1 8.85 mS cm -1 The retention rates were 95.6%, 92.1%, 88.9%, 85.8%, and 82.7%, respectively. Using lithium metal as the symmetrical electrode, Li 5.3 PS 4.3 Cl 0.7 Br 0.76 I 0.24 A sulfide solid electrolyte was used as the electrolyte layer, and the cells were assembled into a symmetrical battery. Cyclic testing was performed using the Blue Electric CT2001A battery testing system. The battery was tested at a current density of 0.5 mAcm⁻¹. -2 It can be stably cycled for 8000 hours; Li 5.3 PS 4.3 Cl 0.7 Br 0.76 I 0.24 A sulfide solid electrolyte, a LiCoO2 cathode, and a lithium metal anode were assembled into an all-solid-state battery. The battery's electrochemical performance was tested using the Blue Electric CT2001A battery testing system. The charge-discharge voltage range was 3.0~4.2 V, the rate was 1C, and constant rate charge-discharge was performed. After 500 cycles, the capacity retention rate was 86.9%. Example 5

[0020] Under an argon atmosphere, Li₂S, P₂S₅, P, LiCl, LiF, LiBr, TeO₂, and I₂ with a purity of ≥99% were weighed out according to stoichiometric ratios and placed in an agate mortar. After grinding for 30 minutes under conditions where the water content was less than 10 ppm, Li₂ was obtained. 5.4 PS 4. 4F 0.03 O 0.02 Cl 0.65 Br 0.8 I 0.09 Te 0.01 Precursor powder; The precursor powder was sintered in a muffle furnace under an inert atmosphere (argon) at a heating rate of 4°C / min to 495°C for 4 hours. After natural cooling to room temperature, the powder was ground uniformly to obtain Li. 5.4 PS 4.4 F 0.03 O 0.02 Cl 0.65 Br 0.8 I 0.09 Te 0.01 Sulfide solid electrolyte.

[0021] Performance testing and battery assembly Grind Li 5.4 PS 4.4 F 0.03 O 0.02 Cl 0.65 Br 0.8 I 0.09 Te 0.01 The sulfide solid electrolyte powder was pressed into tablets, and its room temperature ionic conductivity was measured to be 13.2 mS / cm. -1 After exposure to dew point temperatures of -60℃, -50℃, and -40℃ in a dry room for 60 minutes, the room temperature conductivity was measured to be 12.84 mS / cm. -1 12.49 mS cm -1 12.08 mS cm -1 The retention rates were 97.3%, 94.6%, and 91.5%, respectively; after treatment with toluene, butyl butyrate, diethyl ether, acetonitrile, and tetrahydrofuran, the room temperature ionic conductivity was 12.46 mS / cm. -1 12.08 mS cm -1 11.58 mS cm -1 11.17 mS cm -1 10.77 mS cm -1 The retention rates were 94.4%, 91.5%, 87.7%, 84.6%, and 81.6%, respectively. Using lithium metal as the symmetrical electrode, Li 5.4 PS 4.4 F 0.03 O 0.02 Cl 0.65 Br 0.8 I 0.09 Te 0.01 A sulfide solid electrolyte was used as the electrolyte layer, and a symmetrical cell was assembled. Cyclic testing was performed using the Blue Electric CT2001A battery testing system. The cell operated at a current density of 0.5 mA cm⁻¹. -2 It can be stably cycled for 5000 hours; Li5.4 PS 4.4 F 0.03 O 0.02 Cl 0.65 Br 0.8 I 0.09 Te 0.01 A sulfide solid electrolyte, a LiCoO2 cathode, and a lithium metal anode were assembled into an all-solid-state battery. The battery's electrochemical performance was tested using the Blue Electric CT2001A battery testing system. The charge-discharge voltage range was 3.0~4.2 V, the rate was 1C, and constant rate charge-discharge was performed. After 500 cycles, the capacity retention rate was 91.6%. Example 6

[0022] Li₂S, P₂S₅, LiCl, LiBr, and LiI, each with a purity of ≥99%, were weighed according to stoichiometry and placed in an agate mortar. After grinding for 30 minutes under conditions where the water content was less than 10 ppm, Li₂S was obtained. 5.5 PS 4.5 Cl 0.8 Br 0.6 I 0.1 Precursor powder; The precursor powder was sintered in a muffle furnace under an inert atmosphere (argon) at a heating rate of 4°C / min to 505°C for 4 hours. After natural cooling to room temperature, the powder was ground uniformly to obtain Li. 5.5 PS 4.5 Cl 0.8 Br 0.6 I 0.1 Sulfide solid electrolyte.

[0023] Performance testing and battery assembly Grind Li 5.5 PS 4.5 Cl 0.8 Br 0.6 I 0.1 The sulfide solid electrolyte powder was pressed into tablets, and its room temperature ionic conductivity was measured to be 14.1 mS / cm. -1 After being exposed to dew point temperatures of -60℃, -50℃, and -40℃ in a dry room for 60 minutes, the room temperature conductivity was measured to be 13.51 mS / cm. -1 13.35 mS cm -1 13.08 mS cm -1 The retention rates were 95.8%, 94.7%, and 92.8%, respectively; after treatment with toluene, butyl butyrate, diethyl ether, acetonitrile, and tetrahydrofuran, the room temperature ionic conductivity was 13.1 mS / cm. -1 12.92 mS cm -112.55 mS cm -1 12.11 mS cm -1 11.67 mS cm -1 The retention rates were 92.9%, 91.6%, 89%, 85.9%, and 82.8%, respectively. Using lithium metal as the symmetrical electrode, Li 5.5 PS 4.5 Cl 0.8 Br 0.6 I 0.1 A sulfide solid electrolyte was used as the electrolyte layer, and a symmetrical cell was assembled. Cyclic testing was performed using the Blue Electric CT2001A battery testing system. The cell operated at a current density of 0.5 mA cm⁻¹. -2 It can be stably cycled for 5500 hours; Li 5.5 PS 4.5 Cl 0.8 Br 0.6 I 0.1 A sulfide solid electrolyte, a LiCoO2 cathode, and a lithium metal anode were assembled into an all-solid-state battery. The battery's electrochemical performance was tested using the Blue Electric CT2001A battery testing system. The charge-discharge voltage range was 3.0~4.2 V, the rate was 1C, and constant rate charge-discharge was performed. After 500 cycles, the capacity retention rate was 88.5%. Example 7

[0024] Li₂S, P₂S₅, LiCl, LiBr, and LiI, each with a purity of ≥99%, were weighed according to stoichiometry and placed in an agate mortar. After grinding for 30 minutes under conditions where the water content was less than 10 ppm, Li₂S was obtained. 5.6 PS 4.6 Cl 0.6 Br 0.6 I 0.2 Precursor powder; The precursor powder was sintered in a muffle furnace under an inert atmosphere (argon) at a heating rate of 4°C / min to 515°C for 4 hours. After natural cooling to room temperature, the powder was ground uniformly to obtain Li. 5.6 PS 4.6 Cl 0.6 Br 0.6 I 0.2 Sulfide solid electrolyte.

[0025] Performance testing and battery assembly Grind Li 5.6 PS 4.6 Cl 0.6 Br 0.6 I 0.2The sulfide solid electrolyte powder was pressed into tablets, and its room temperature ionic conductivity was measured to be 17.9 mS / cm. -1 After exposure to dew point temperatures of -60℃, -50℃, and -40℃ in a dry room for 60 minutes, the room temperature conductivity was measured to be 17.02 mS / cm. -1 16.36 mS cm -1 16.09 mS cm -1 The retention rates were 95.1%, 91.4%, and 89.9%, respectively; after treatment with toluene, butyl butyrate, diethyl ether, acetonitrile, and tetrahydrofuran, the room temperature ionic conductivity was 16.5 mS / cm. -1 15.81 mS cm -1 15.41 mS cm -1 14.87 mS cm -1 14.33 mS cm -1 The retention rates were 92.2%, 88.3%, 86.1%, 83.1%, and 80.1%, respectively. Using lithium metal as the symmetrical electrode, Li 5.6 PS 4.6 Cl 0.6 Br 0.6 I 0.2 A sulfide solid electrolyte was used as the electrolyte layer, and a symmetrical cell was assembled. Cyclic testing was performed using the Blue Electric CT2001A battery testing system. The cell operated at a current density of 0.5 mA cm⁻¹. -2 It can be stably cycled for 8500 hours; Li 5.6 PS 4.6 Cl 0.6 Br 0.6 I 0.2 A sulfide solid electrolyte, a LiCoO2 cathode, and a lithium metal anode were assembled into an all-solid-state battery. The battery's electrochemical performance was tested using the Blue Electric CT2001A battery testing system. The charge-discharge voltage range was 3.0~4.2 V, the rate was 1C, and constant rate charge-discharge was performed. After 500 cycles, the capacity retention rate was 84.8%. Example 8

[0026] Li₂S, P₂S₅, P, S, LiF, PCl₅, PBr₃, and I₂, each with a purity of ≥99%, were weighed according to stoichiometric ratios and placed in an agate mortar. After grinding for 30 minutes under conditions where the water content was less than 10 ppm, Li₂S was obtained. 5.4 PS 4.4 F 0.07 Cl 0.83 Br 0.6 I 0.1 Precursor powder; The precursor powder was sintered in a muffle furnace under an inert atmosphere (argon) at a heating rate of 4°C / min to 485°C for 4 hours. After natural cooling to room temperature, the powder was ground uniformly to obtain Li. 5.4 PS 4.4 F 0.07 Cl 0.83 Br 0.6 I 0.1 Sulfide solid electrolyte.

[0027] Performance testing and battery assembly Grind Li 5.4 PS 4.4 F 0.07 Cl 0.83 Br 0.6 I 0.1 The sulfide solid electrolyte powder was pressed into tablets, and its room temperature ionic conductivity was measured to be 15.7 mS / cm. -1 After exposure to dew point temperatures of -60℃, -50℃, and -40℃ in a dry room for 60 minutes, the room temperature conductivity was measured to be 15.1 mS / cm. -1 14.7 mS cm -1 14.15 mS cm -1 The retention rates were 96.2%, 93.6%, and 90.1%, respectively; after treatment with toluene, butyl butyrate, diethyl ether, acetonitrile, and tetrahydrofuran, the room temperature ionic conductivity was 14.65 mS / cm. -1 14.21 mS cm -1 13.55 mS cm -1 13.08 mS cm -1 12.61 mS cm -1 The retention rates were 93.3%, 90.5%, 86.3%, 83.3%, and 80.3%, respectively. Using lithium metal as the symmetrical electrode, Li 5.4 PS 4.4 F 0.07 Cl 0.83 Br 0.6 I 0.1 A sulfide solid electrolyte was used as the electrolyte layer, and the cells were assembled into a symmetrical battery. Cyclic testing was performed using the Blue Electric CT2001A battery testing system. The battery was tested at a current density of 0.5 mAcm⁻¹. -2 It can be stably cycled for 6500 hours; Li 5.4 PS 4.4 F 0.07 Cl 0.83 Br 0.6 I 0.1A sulfide solid electrolyte, a LiCoO2 cathode, and a lithium metal anode were assembled into an all-solid-state battery. The battery's electrochemical performance was tested using the Blue Electric CT2001A battery testing system. The charge-discharge voltage range was 3.0~4.2 V, the rate was 1C, and constant rate charge-discharge was performed. After 500 cycles, the capacity retention rate was 85.9%. Example 9

[0028] Li₂S, P₂S₅, LiCl, LiBr, and LiI, each with a purity of ≥99%, were weighed according to stoichiometry and placed in an agate mortar. After grinding for 30 minutes under conditions where the water content was less than 10 ppm, Li₂S was obtained. 5.5 PS 4.5 Cl 0.8 Br0 .5 I 0.2 Precursor powder; The precursor powder was sintered in a muffle furnace under an inert atmosphere (argon) at a heating rate of 4°C / min to 515°C for 4 hours. After natural cooling to room temperature, the powder was ground uniformly to obtain Li. 5.5 PS 4.5 Cl 0.8 Br0 .5 I 0.2 Sulfide solid electrolyte.

[0029] Performance testing and battery assembly Grind Li 5.5 PS 4.5 Cl 0.8 Br 0.5 I 0.2 The sulfide solid electrolyte powder was pressed into tablets, and its room temperature ionic conductivity was measured to be 16.6 mS / cm. -1 After exposure to dew point temperatures of -60℃, -50℃, and -40℃ in a dry room for 60 minutes, the room temperature conductivity was measured to be 15.89 mS / cm. -1 15.32 mS cm -1 14.89 mS cm -1 The retention rates were 95.7%, 92.3%, and 89.7%, respectively; after treatment with toluene, butyl butyrate, diethyl ether, acetonitrile, and tetrahydrofuran, the room temperature ionic conductivity was 15.4 mS / cm. -1 14.81 mS cm -1 14.26 mS cm -1 13.76 mS cm -1 13.26 mS cm -1 The retention rates were 92.8%, 89.2%, 85.9%, 82.9%, and 79.9%, respectively. Using lithium metal as the symmetrical electrode, Li 5.5 PS 4.5 Cl 0.8 Br 0.5 I 0.2 A sulfide solid electrolyte was used as the electrolyte layer, and a symmetrical cell was assembled. Cyclic testing was performed using the Blue Electric CT2001A battery testing system. The cell operated at a current density of 0.5 mA cm⁻¹. -2 It can be stably cycled for 7000 hours; Li 5.5 PS 4.5 Cl 0.8 Br 0.5 I 0.2 A sulfide solid electrolyte, a LiCoO2 cathode, and a lithium metal anode were assembled into an all-solid-state battery. The battery's electrochemical performance was tested using the Blue Electric CT2001A battery testing system. The charge-discharge voltage range was 3.0~4.2 V, the rate was 1C, and constant rate charge-discharge was performed. After 500 cycles, the capacity retention rate was 87.9%. Example 10

[0030] Li₂S, P₂S₅, LiCl, LiBr, and LiI, each with a purity of ≥99%, were weighed according to stoichiometry and placed in an agate mortar. After grinding for 30 minutes under conditions where the water content was less than 10 ppm, Li₂S was obtained. 5.3 PS 4.3 Cl 0.8 Br 0.7 I 0.2 Precursor powder; The precursor powder was sintered in a muffle furnace under an inert atmosphere (argon) at a heating rate of 4°C / min to 475°C for 4 hours. After natural cooling to room temperature, the powder was ground uniformly to obtain Li. 5.3 PS 4.3 Cl 0.8 Br 0.7 I 0.2 Sulfide solid electrolyte.

[0031] Performance testing and battery assembly Grind Li 5.3 PS 4.3 Cl 0.8 Br 0.7 I 0.2 The sulfide solid electrolyte powder was pressed into tablets, and its room temperature ionic conductivity was measured to be 21.2 mS / cm. -1 After exposure to dew point temperatures of -60℃, -50℃, and -40℃ in a dry room for 60 minutes, the room temperature conductivity was measured to be 19.99 mS / cm. -119.25 mS cm -1 18.7 mS cm -1 The retention rates were 94.3%, 90.8%, and 88.2%, respectively; after treatment with toluene, butyl butyrate, diethyl ether, acetonitrile, and tetrahydrofuran, the room temperature ionic conductivity was 19.38 mS / cm. -1 18.59 mS cm -1 17.89 mS cm -1 17.26 mS cm -1 16.64 mS cm -1 The retention rates were 91.4%, 87.7%, 84.4%, 78.5%, and 81.4%, respectively. Using lithium metal as the symmetrical electrode, Li 5.3 PS 4.3 Cl 0.8 Br 0.7 I 0.2 A sulfide solid electrolyte was used as the electrolyte layer, and a symmetrical cell was assembled. Cyclic testing was performed using the Blue Electric CT2001A battery testing system. The cell operated at a current density of 0.5 mA cm⁻¹. -2 It can be stably cycled for 7500 hours; Li 5.3 PS 4.3 Cl 0.8 Br 0.7 I 0.2 A sulfide solid electrolyte, a LiCoO2 cathode, and a lithium metal anode were assembled into an all-solid-state battery. The battery's electrochemical performance was tested using the Blue Electric CT2001A battery testing system. The charge-discharge voltage range was 3.0~4.2 V, the rate was 1C, and constant rate charge-discharge was performed. After 500 cycles, the capacity retention rate was 84.2%.

[0032] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that, under an argon atmosphere, Li₂S, P₂S₅, and LiCl with a purity of ≥99% were weighed according to stoichiometric ratio and placed in an agate mortar. After grinding for 30 minutes under conditions where the water content was less than 10 ppm, Li₂S was obtained. 5.5 PS 4.5 Cl 1.5 Precursor powder; other steps are the same as in Example 1.

[0033] Performance testing and battery assembly Grind Li 5.5 PS 4.5 Cl 1.5 The sulfide solid electrolyte powder was pressed into tablets, and its room temperature ionic conductivity was measured to be 10.1 mS / cm. -1After exposure to dew point temperatures of -60℃, -50℃, and -40℃ in a dry room for 60 minutes, the room temperature conductivity was measured to be 8.15 mS / cm. -1 7.5 mS cm -1 6.27 mS cm -1 The retention rates were 80.7%, 74.3%, and 62.1%, respectively; after treatment with toluene, butyl butyrate, diethyl ether, acetonitrile, and tetrahydrofuran, the room temperature ionic conductivity was 7.3 mS / cm. -1 7.01 mS cm -1 8.29 mS cm -1 7.62 mS cm -1 6.14 mS cm -1 The retention rates were 72.3%, 69.4%, 82.1%, 75.4%, and 60.8%, respectively. Using lithium metal as the symmetrical electrode, Li 5.5 PS 4.5 Cl 1.5 A sulfide solid electrolyte was used as the electrolyte layer, and a symmetrical cell was assembled. Cyclic testing was conducted using the Blue Electric CT2001A battery testing system. The cell operated at a current density of 0.1 mA cm⁻¹. -2 It can be stably cycled for 1000 hours; Li 5.5 PS 4.5 Cl 1.5 A sulfide solid electrolyte, a LiCoO2 cathode, and a lithium metal anode were assembled into an all-solid-state battery. The battery's electrochemical performance was tested using the Blue Electric CT2001A battery testing system. The charge-discharge voltage range was 3.0~4.2 V, the rate was 1C, and constant rate charge-discharge was performed. After 500 cycles, the capacity retention rate was 39.4%.

[0034] In Comparative Example 1, the sulfide solid electrolyte has only Cl as a halogen site, while in Example 1, the halogen sites are a high-entropy blend of Cl, Br, and I. By comparing the two, it can be seen that when the halogen site elements of the sulfide solid electrolyte are highly entropy blended, the sulfide solid electrolyte exhibits superior room temperature ionic conductivity, stability to air, organic solvents, and lithium. At the same time, the all-solid-state lithium battery assembled with the high-entropy sulfide solid electrolyte has better cycle stability.

[0035] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that, under an argon atmosphere, Li₂S, P₂S₅, LiCl, LiBr, and LiI with a purity of ≥99% were weighed according to stoichiometric ratio and placed in an agate mortar. After grinding for 30 minutes under conditions where the water content was less than 10 ppm, Li was obtained. 5.5 PS 4.5Cl 0.5 Br 0.5 I 0.5 Precursor powder; other steps are the same as in Example 1.

[0036] Performance testing and battery assembly Grind Li 5.5 PS 4.5 Cl 0.5 Br 0.5 I 0.5 The sulfide solid electrolyte powder was pressed into tablets, and its room temperature ionic conductivity was measured to be 6.4 mS / cm. -1 After exposure to dew point temperatures of -60℃, -50℃, and -40℃ in a dry room for 60 minutes, the room temperature conductivity was measured to be 3.67 mS / cm. -1 2.9 mS cm -1 2.48 mS cm -1 The retention rates were 57.3%, 45.3%, and 38.7%, respectively; after treatment with toluene, butyl butyrate, diethyl ether, acetonitrile, and tetrahydrofuran, the room temperature ionic conductivity was 2.21 mS / cm. -1 1.72mS cm -1 2.64 mS cm -1 2.55 mS cm -1 1.43 mS cm -1 The retention rates were 34.5%, 26.9%, 41.3%, 39.8%, and 22.4%, respectively. Using lithium metal as the symmetrical electrode, Li 5.5 PS 4.5 Cl 0.5 Br 0.5 I 0.5 A sulfide solid electrolyte was used as the electrolyte layer, and a symmetrical cell was assembled. Cyclic testing was conducted using the Blue Electric CT2001A battery testing system. The cell operated at a current density of 0.1 mA cm⁻¹. -2 It can be stably cycled for 2000 hours; Li 5.5 PS 4.5 Cl 0.5 Br 0.5 I 0.5 A sulfide solid electrolyte, a LiCoO2 cathode, and a lithium metal anode were assembled into an all-solid-state battery. The battery's electrochemical performance was tested using the Blue Electric CT2001A battery testing system. The charge-discharge voltage range was 3.0~4.2 V, the rate was 1C, and constant rate charge-discharge was performed. After 500 cycles, the capacity retention rate was 29.3%.

[0037] Comparative Example 2's sulfide solid electrolyte contains Cl, Br, and I elements at its halogen sites, but the doping ratio is relatively high, with α=0, β=0.333, γ=0.333, and δ=0.333, which does not satisfy the conditions 0<δ<0.144 and α+δ<0.2. Example 1's halogen sites are a high-entropy blend of Cl, Br, and I elements, with α=0, β=0.467, γ=0.467, and δ=0.067, satisfying the conditions α+β+γ+δ=1, 0≤α≤0.1, 0<β≤1, 0<δ<0.144, and α+δ<0.2. By comparing the two, it can be seen that when the high-entropy blend of halogen sites in the sulfide solid electrolyte meets the design conditions, the sulfide solid electrolyte exhibits superior room-temperature ionic conductivity, stability to air, organic solvents, and lithium. At the same time, the all-solid-state lithium battery assembled with the high-entropy sulfide solid electrolyte has better cycle stability. When the high-entropy blending of halogen site elements in sulfide solid electrolytes exceeds the design range, the mismatch of doping site elements will lead to phase segregation, which in turn will cause a significant decrease in the room temperature ionic conductivity of the electrolyte, and at the same time, it will cause a significant reduction in the stability of the electrolyte to air, organic solvents and lithium.

Claims

1. A high-entropy halogen-site doped sulfide solid electrolyte, characterized in that: Its general chemical formula is Li 6-x PS 5-x [(F y O 1-y ) α (Cl y S 1-y ) β (Br y Se 1-y ) γ (I y Te 1-y ) δ ] 1+x , among them, 0.4≤x≤0.7, 0.5≤y≤1, α+β+γ+δ=1, 0≤α≤0.1, 0<β≤1, 0<δ<0.144, α+δ<0.

2.

2. The solid electrolyte as described in claim 1, characterized in that: The room temperature ionic conductivity of the solid electrolyte is 1×10⁻⁶. -2 S / cm ~ 5×10 -2 S / cm.

3. The method for preparing a solid electrolyte as described in claim 1, characterized in that, Includes the following steps: S1. According to the general formula Li 6-x PS 5-x [(F y O 1-y ) α (Cl y S 1-y ) β (Br y Se 1-y ) γ (I y Te 1-y ) δ ] 1+x Lithium source, phosphorus source, sulfur source, fluorine source, oxygen source, chlorine source, bromine source, selenium source, tellurium source and iodine source in stoichiometric ratios were weighed and physically mixed to obtain precursor powder. S2. The precursor powder is calcined at high temperature in an inert atmosphere or vacuum and then naturally cooled to room temperature to obtain a high-entropy halogen-doped sulfide solid electrolyte.

4. The method as described in claim 3, characterized in that: In step S1, the physical mixing method is mechanical stirring, mechanical vibration, high-energy ball milling or roller milling, and the mixing time is 0.5 to 48 hours.

5. The method as described in claim 3, characterized in that: In step S1, the purity of the lithium source, phosphorus source, sulfur source, fluorine source, oxygen source, chlorine source, bromine source, selenium source, tellurium source and iodine source is not less than 99%, and the water content is less than 10 ppm.

6. The method as described in claim 3, characterized in that: In step S2, the conditions for high-temperature calcination are: inert atmosphere or vacuum sintering, temperature 400~600℃, and treatment time 0.1~24 hours.

7. The method as described in claim 3, characterized in that: In step S2, the material that has been calcined and naturally cooled to room temperature needs to be crushed and ground to obtain the high-entropy halogen-doped sulfide solid electrolyte.

8. The application of the solid electrolyte as described in any one of claims 1-2 or the solid electrolyte prepared by the method described in any one of claims 3-7 in all-solid-state batteries.

9. The application as described in claim 8, characterized in that: The all-solid-state battery is an all-solid-state lithium secondary battery, which includes a positive electrode, a negative electrode, and a solid electrolyte.

10. The application of the solid electrolyte according to any one of claims 1-2 or the solid electrolyte prepared by the method according to any one of claims 3-7 in a symmetric battery, characterized in that: Lithium metal is used as the symmetrical electrode, and sulfide solid electrolyte is used as the electrolyte layer.