Sulfide solid-state electrolyte precursor, electrolyte precursor having siloxane, preparation method for sulfide solid-state electrolyte, and battery

Abstract

A sulfide solid-state electrolyte precursor, an electrolyte precursor having siloxane, a preparation method for a sulfide solid-state electrolyte, and a battery, relating to the technical field of batteries. The method comprises: preparing electrolyte raw materials according to a stoichiometric ratio in the chemical formula of a sulfide solid-state electrolyte, adding a first solvent, and performing ball milling to form an electrolyte precursor; placing the electrolyte precursor in a second solvent containing siloxane, and heating and stirring the mixture, so that the siloxane is coated on the electrolyte precursor to form an electrolyte precursor having siloxane; and sintering the electrolyte precursor having siloxane to obtain a doped and coated sulfide electrolyte. By forming a coating layer on the outer side of the sulfide electrolyte, the air stability of the sulfide solid-state electrolyte is greatly improved, and the interfacial stability between the sulfide electrolyte and lithium metal is improved, thereby achieving high cycle stability of all-solid-state lithium metal batteries.

Description

Sulfide solid electrolyte precursor, electrolyte precursor with siloxane, sulfide solid electrolyte preparation method and battery

[0001] Cross-reference to Related Applications

[0002] The present application claims priority to the Chinese patent application No. 202410955672.1, filed on July 16, 2024, entitled "Sulfide solid electrolyte precursor, sulfide solid electrolyte preparation method and battery", the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of batteries, in particular to a sulfide solid electrolyte precursor, electrolyte precursor with siloxane, sulfide solid electrolyte preparation method and battery. BACKGROUND

[0004] Lithium batteries are used as a kind of energy storage device, which are mainly applied in mobile devices, electric vehicles and household appliances, etc. In modern society, lithium batteries have been widely used and become an essential part of many devices and products.

[0005] In some related technologies, it is found through research that the use of solid-state electrolyte instead of the original liquid electrolyte in lithium-ion batteries can greatly solve the safety problem of the battery, and the solid-state electrolyte has a wide electrochemical window, which is helpful for the uniform deposition of lithium. Among them, sulfide solid electrolyte is considered to be a solid-state electrolyte material with broad application prospects due to its excellent mechanical properties and high ionic conductivity, and its ionic conductivity can reach a level comparable to that of liquid electrolyte.

[0006] However, there are still some problems in the actual use of sulfide electrolyte. For example, sulfide solid electrolyte is extremely easy to hydrolyze in humid air, which can reduce the ionic conductivity of the electrolyte and greatly limit the application and production of sulfide solid electrolyte; and when the sulfide solid electrolyte contacts with lithium metal, serious interface side reactions occur, causing the battery interface impedance to become large, which affects the performance of the all-solid-state battery. SUMMARY

[0007] In order to solve at least one problem mentioned in the above background, the present application provides a sulfide solid electrolyte precursor, electrolyte precursor with siloxane, sulfide solid electrolyte preparation method and battery. By forming a coating layer outside the sulfide electrolyte, the air stability of the sulfide solid electrolyte is greatly improved, and the stability of the sulfide electrolyte to the lithium metal interface is improved, so as to realize the high cycle stability of the all-solid-state lithium metal battery.

[0008] The specific technical solutions provided by the embodiments of the present application are as follows:

[0009] In a first aspect, a sulfide solid electrolyte precursor is provided, the sulfide solid electrolyte precursor has a chemical formula of Li 6-m PS 5-m X 1+m ; wherein 0

[0010] The sulfide solid electrolyte precursor formed according to the above chemical formula has a structure of the surface of the sulfide solid electrolyte precursor that is more suitable for subsequent surface coating in terms of the interaction force between the sulfide solid electrolyte precursor particles and other particles, and can ensure subsequent doping of siloxane into the electrolyte body phase, so that the sulfide solid electrolyte after doping and coating has high stability.

[0011] In a specific embodiment, 0

[0012] By controlling the ratio of each element in the sulfide solid electrolyte precursor within a reasonable range, the particles in the solid are fully reacted, which is beneficial to doping and coating.

[0013] In a second aspect, an electrolyte precursor with siloxane is provided, including new electrolyte precursor particles and siloxane coated on at least part of the surface of the new electrolyte precursor particles;

[0014] The new electrolyte precursor includes Li 6-m PS 5-m X 1+m , 0

[0015] The siloxane is Si n O n-1 H 2n+2 or (H2SiO) n , n is an integer greater than or equal to 2.

[0016] In a specific embodiment, the crystallinity of the new electrolyte precursor is less than the crystallinity of the sulfide solid electrolyte precursor;

[0017] The sulfide solid electrolyte precursor has a chemical formula of Li 6-m PS 5-m X 1+m ; wherein 0 6-m 5-m 1+m ; wherein 0

[0018] In one specific embodiment, the new electrolyte precursor is obtained by adding a first solvent to the sulfide solid electrolyte; wherein the first solvent is an alkane solvent.

[0019] In a third aspect, a method for preparing a sulfide solid electrolyte using the sulfide solid electrolyte precursor as described above is provided, the method comprising: configuring electrolyte raw materials according to the stoichiometric ratio in the chemical formula of the sulfide solid electrolyte precursor, adding a first solvent and performing ball milling to form a new electrolyte precursor; placing the new electrolyte precursor in a second solvent containing siloxane, heating and stirring to allow the siloxane to coat the new electrolyte precursor, forming an electrolyte precursor with siloxane; and sintering the electrolyte precursor with siloxane to obtain a doped and coated sulfide electrolyte.

[0020] By the above scheme, the electrolyte raw materials are configured according to the stoichiometric ratio in the chemical formula of the precursor, then a first solvent is added for dispersion and ball milling to prepare a dispersed new precursor solution, the new precursor solution is placed in a second solvent containing siloxane, heated and stirred to allow the siloxane to coat the new electrolyte precursor, then sintered to allow the siloxane to decompose to form a silica coating layer and coat the surface of the new electrolyte precursor, while doping in the electrolyte body phase to form silica, and the thickness of the coating layer is controlled by controlling the concentration of the siloxane solution in this process, thereby obtaining a silica-coated and doped sulfide electrolyte, wherein the silica coating on the surface of the electrolyte greatly improves the air stability of the electrolyte and improves the stability of the electrolyte to the lithium metal interface, and the silica doped in the electrolyte by decomposition further improves the intrinsic air stability of the prepared electrolyte, achieving high cycle stability of the all-solid-state lithium metal battery.

[0021] In one specific embodiment, the method further comprises: configuring the electrolyte raw materials according to the stoichiometric ratio in the chemical formula of the sulfide solid electrolyte precursor, adding a first solvent, and performing ball milling to form a precursor solution; and heating and drying the precursor solution to obtain the new electrolyte precursor.

[0022] By dispersing the electrolyte precursor in the first solvent to form a precursor solution, it can be ensured that the electrolyte precursor is uniformly dispersed, and by heating and drying, on the one hand, impurities on the surface of the new electrolyte precursor particles can be removed, and on the other hand, the new electrolyte precursor aggregated into a group can be uniformly dispersed to obtain the dispersed new electrolyte precursor particles.

[0023] In one specific embodiment, the first solvent is an alkane solvent; further, the first solvent includes one or more of n-heptane, hexane or octane.

[0024] The ball milling speed is 200 rpm to 800 rpm; further, the ball milling speed is 400 rpm to 600 rpm;

[0025] The ball milling time is 10h to 60h; further, the ball milling time is 20h to 48h.

[0026] The drying temperature of the precursor solution is 60℃~140℃; further, the drying temperature of the precursor solution is 80℃~120℃.

[0027] The drying time of the precursor solution is 8h to 50h; further, the drying time of the precursor solution is 10h to 40h.

[0028] By controlling the type of the first solvent and the rotation speed and time parameters during ball milling, it is ensured that the solid electrolyte precursor can be dispersed to form a uniform precursor solution, which is beneficial for subsequently coating the surface of the new electrolyte precursor with siloxane.

[0029] In one specific embodiment, the chemical formula of the siloxane is Si. n O n-1 H 2n+2 Or (H2SiO) n Where n is an integer greater than or equal to 2; the mass concentration of siloxane in the second solvent is 1% to 9%; further, the mass concentration of siloxane in the second solvent is 2% to 6%;

[0030] The second solvent is an aromatic hydrocarbon solvent; further, the second solvent includes one or more of benzene, toluene, or chlorobenzene.

[0031] By controlling the type and mass concentration of siloxanes in the second solvent, the thickness of the coating layer formed on the sulfide solid electrolyte can be controlled. By controlling the thickness of the coating layer on the surface of the sulfide solid electrolyte within a reasonable range, the final prepared sulfide solid electrolyte can be ensured to have both good interfacial stability and good ionic conductivity.

[0032] In one specific embodiment, the method further includes: coating a new electrolyte precursor with siloxane and drying it to form an electrolyte precursor having siloxane.

[0033] The drying temperature is 60℃~140℃; further, the drying temperature is 70℃~130℃; the drying time is 10h~50h; further, the drying time is 12h~48h.

[0034] The electrolyte precursor with siloxane is dried after the siloxane is coated on the electrolyte precursor, and the temperature and time in the drying process are controlled in a reasonable range to obtain the electrolyte precursor with stable surface properties and siloxane.

[0035] In one specific embodiment, the method further comprises: placing the electrolyte precursor with siloxane in a tube furnace with an inert gas atmosphere for sintering, forming a silicon dioxide coating layer on the surface of the electrolyte, and doping silicon dioxide in the electrolyte body phase to form the doped coated sulfide electrolyte.

[0036] The thickness of the silicon dioxide coating layer is 1 nm to 500 nm; further, the thickness of the silicon dioxide coating layer is 10 nm to 50 nm.

[0037] The inert gas includes one or more of nitrogen, helium, neon, argon, krypton, xenon, or radon.

[0038] By sintering the electrolyte precursor with siloxane in the tube furnace with an inert gas atmosphere, the siloxane undergoes pyrolysis to form a silicon dioxide coating layer on the surface of the electrolyte, and part of the silicon dioxide is doped in the bulk phase of the electrolyte, thereby forming a doped coated sulfide electrolyte. By controlling the thickness of the silicon dioxide coating layer in a reasonable range, the sulfide solid-state electrolyte prepared finally has good interface stability and good ionic conductivity.

[0039] In one specific embodiment, the sintering temperature is 300℃ to 800℃; further, the sintering temperature is 400℃ to 600℃.

[0040] By controlling the temperature in the sintering process, the siloxane on the surface of the electrolyte precursor can smoothly undergo pyrolysis to form a silicon dioxide coating layer.

[0041] In a fourth aspect, a battery is provided, comprising a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte is prepared by the method described above.

[0042] The embodiments of the present application have the following beneficial effects:

[0043] 1. The embodiments of the present application provide that by forming a silicon dioxide coating layer outside the sulfide electrolyte and doping silicon dioxide in the bulk phase of the electrolyte, the air stability of the sulfide solid-state electrolyte is improved, and the stability of the sulfide electrolyte to the lithium metal interface is improved, so as to realize the high cycle stability of the all-solid-state lithium metal battery. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description only constitute some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0045] FIG. 1 shows a schematic diagram of a method for preparing a sulfide solid-state electrolyte according to the present application;

[0046] FIG. 2 shows an SEM image of a sulfide solid-state electrolyte prepared according to Embodiment One of the present application;

[0047] FIG. 3 shows a TEM image of a sulfide solid-state electrolyte prepared according to Embodiment One of the present application. DETAILED DESCRIPTION

[0048] In order to make the objects, technical solutions and advantages of the present application clearer, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application herein only for the purpose of describing specific embodiments and is not intended to limit the present application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0050] The present embodiment provides a sulfide solid-state electrolyte precursor, the chemical formula of the sulfide solid-state electrolyte is Li 6-m PS 5-m X 1+m ; wherein 0 < m < 2.5; wherein the element X includes but is not limited to one or more of fluorine, chlorine, bromine, iodine.

[0051] For example, the element X is selected as chlorine and bromine, the electrolyte raw material is selected as Li2S, P2S5, LiCl and LiBr, and when m is configured as 2.4, the chemical formula of the sulfide solid-state electrolyte is Li 3.7 PS 2.6 X 3.4, the electrolyte raw material Li2S, P2S5, LiCl and LiBr are configured in a ratio of Li2S:P2S5:LiCl:LiBr = 0.3:0.98:3:3.8.

[0052] For example, when the element X is selected to be chlorine and bromine, and the selected electrolyte raw material is Li2S, P2S5, LiCl and LiBr, when m is configured to be 0.1, the chemical formula of the sulfide solid electrolyte is Li 5.9 PS 4.9 X 1.1 , the electrolyte raw material Li2S, P2S5, LiCl and LiBr are configured in a ratio of Li2S:P2S5:LiCl:LiBr = 4.8:1:1:1.2.

[0053] In one specific embodiment, 0 < m < 1 in the chemical formula of the sulfide solid electrolyte precursor; further, 0.2 ≤ m ≤ 0.7.

[0054] For example, when the element X is selected to be chlorine and bromine, and the selected electrolyte raw material is Li2S, P2S5, LiCl and LiBr, when m is configured to be 0.5, the chemical formula of the sulfide solid electrolyte is Li 5.5 PS 4.5 X 1.5 , that is, the electrolyte raw material Li2S, P2S5, LiCl and LiBr are configured in a ratio of Li2S:P2S5:LiCl:LiBr = 4:1:1.6:1.4.

[0055] When m is configured to be 0.7, the chemical formula of the sulfide solid electrolyte is Li 5.3 PS 4.3 X 1.7 , the electrolyte raw material Li2S, P2S5, LiCl and LiBr are configured in a ratio of Li2S:P2S5:LiCl:LiBr = 3.6:1:1.6:1.8.

[0056] When m is configured to be 0.2, the chemical formula of the sulfide solid electrolyte is Li 5.8 PS 4.8 X 1.2 , the electrolyte raw material Li2S, P2S5, LiCl and LiBr are configured in a ratio of Li2S:P2S5:LiCl:LiBr = 4.6:1:1.2:1.2.

[0057] Through exploration, the structure of the sulfide solid electrolyte precursor surface formed according to the element ratio in the above chemical formula is more suitable for subsequent surface coating between other sulfide solid electrolyte precursor particles, and can ensure subsequent doping of siloxane into the electrolyte body phase, so that the sulfide solid electrolyte after doping and coating has higher stability.

[0058] In one embodiment, a method for preparing a sulfide solid electrolyte using the sulfide solid electrolyte precursor as described above is provided, and the method comprises:

[0059] Step 1, configuring electrolyte raw materials according to the metering ratio in the chemical formula of the sulfide solid electrolyte precursor, adding a first solvent and performing ball milling to form a new electrolyte precursor;

[0060] Specifically, the electrolyte raw materials are configured according to the metering ratio in the chemical formula of the sulfide solid electrolyte precursor, a first solvent is added, and ball milling is performed to form a precursor solution; the precursor solution is heated and dried to obtain the new electrolyte precursor.

[0061] The electrolyte raw materials include but are not limited to one or more of Li2S, P2S5, LiCl, LiBr, LiF or LiI.

[0062] The first solvent is an alkane solvent, and specifically the first solvent includes but is not limited to one or more of ethane, propane, butane, pentane, 2-methylbutane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, n-heptane, heptane isomers, octane, 2,2,4-trimethylpentane, 2,3,4-trimethylpentane, 2,2,3-trimethylpentane, nonane, 2,2,5-trimethylhexane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, and octadecane.

[0063] For example, when the element X is chlorine and bromine, and the electrolyte raw materials selected are Li2S, P2S5, LiCl and LiBr, and m is configured as 0.5, the chemical formula of the sulfide solid electrolyte is Li 5.5 PS 4.5 X 1.5 , that is, the ratio of the electrolyte raw materials Li2S, P2S5, LiCl and LiBr is 4:1:1.6:1.4.

[0064] When m is configured as 0.7, the chemical formula of the sulfide solid electrolyte is Li 5.3 PS 4.3 X 1.7At this time, the electrolyte raw materials Li2S, P2S5, LiCl and LiBr are configured in a ratio of Li2S:P2S5:LiCl:LiBr of 3.6:1:1.6:1.8.

[0065] When m is configured as 0.2, at this time, the sulfide solid electrolyte has a chemical formula of Li 5.8 PS 4.8 X 1.2 At this time, the electrolyte raw materials Li2S, P2S5, LiCl and LiBr are configured in a ratio of Li2S:P2S5:LiCl:LiBr of 4.6:1:1.2:1.2.

[0066] Further, after the electrolyte raw materials are configured according to the measurement ratio in the chemical formula of the sulfide solid electrolyte precursor, ball milling is used for dispersion, and the ball milling speed is specifically set to 200 rpm-800 rpm; specifically, the ball milling speed is 400 rpm-600 rpm; the ball milling time is 10 h-60 h; specifically, the ball milling time is 20 h-48 h.

[0067] In order to ensure that the solid electrolyte precursor can be dispersed to form a uniform precursor solution, the drying temperature of the precursor solution is set to 60°C-140°C; specifically, the drying temperature of the precursor solution is 80°C-120°C; the drying time of the precursor solution is 8 h-50 h; specifically, the drying time of the precursor solution is 10 h-40 h.

[0068] Step 2, the new electrolyte precursor is placed in a second solvent containing siloxane, heated and stirred to make the siloxane coat on the new electrolyte precursor, forming an electrolyte precursor with siloxane.

[0069] The siloxane includes chain siloxane and cyclic siloxane, the chemical formula of the chain siloxane is Si n O n-1 H 2n+2 , and the chemical formula of the cyclic siloxane is (H2SiO) n , wherein n is an integer greater than or equal to 2; specifically, the siloxane includes but is not limited to one or several of ethylsiloxane, propylsiloxane, cyclobutylsiloxane or organosiloxane.

[0070] The type and mass concentration of siloxane contained in the second solvent are controlled to realize the control of the thickness of the coating layer formed on the sulfide solid electrolyte; specifically, the mass concentration of siloxane in the second solvent is 1%-9%; specifically, the mass concentration of siloxane in the second solvent is 2%-6%.

[0071] The second solvent is an aromatic hydrocarbon solvent, specifically, the second solvent includes one or more of benzene, toluene, naphthalene, styrene, dimethylacetamide, dimethylformamide, ethylbenzene, cumene, or chlorobenzene.

[0072] In a specific embodiment, specifically including making siloxane coated on the new electrolyte precursor, drying to form an electrolyte precursor with siloxane; wherein the drying temperature is 60-140°C; specifically, the drying temperature is 70-130°C; the drying time is 10-50h; specifically, the drying time is 12-48h.

[0073] Step 3, sintering the electrolyte precursor with siloxane to obtain a doped coated sulfide electrolyte.

[0074] Specifically, the electrolyte precursor with siloxane is placed in a tube furnace with inert gas atmosphere for sintering, forming a silica coating layer on the surface of the electrolyte, and doping silica in the electrolyte phase to form the sulfide solid-state electrolyte.

[0075] Wherein, the thickness of the silica coating layer is 1-500nm; specifically, the thickness of the silica coating layer is 10-50nm; wherein the inert gas includes one or more of nitrogen, helium, neon, argon, krypton, xenon or radon.

[0076] In this embodiment, the sintering temperature is 300-800°C; specifically, the sintering temperature is 400-600°C.

[0077] Through the above scheme, the electrolyte raw materials are configured according to the stoichiometric ratio of the chemical formula in the precursor, then the first solvent is added for dispersion ball milling to prepare a dispersed new precursor solution, the new precursor solution is placed in a second solvent containing siloxane, heated and stirred to make siloxane coated on the new electrolyte precursor, then sintered to form a silica coating layer and coated on the surface of the new electrolyte precursor, while doping silica in the electrolyte phase, and the thickness of the coating layer is controlled by controlling the concentration of the siloxane solution in this process, so as to obtain a silica-coated and doped sulfide electrolyte, wherein the silica is coated on the surface of the electrolyte, which greatly improves the air stability of the electrolyte, and improves the stability of the electrolyte to the lithium metal interface, and the silica doped in the electrolyte further improves the intrinsic air stability of the prepared electrolyte, realizing the high cycle stability of the all-solid-state lithium metal battery.

[0078] Example one

[0079] When m is configured as 0.5, the chemical formula of the sulfide solid-state electrolyte is Li5.5 PS 4.5 X 1.5 , i.e. electrolyte raw materials Li2S, P2S5, LiCl and LiBr, the configuration ratio is 4:1:1.6:1.4; electrolyte raw materials Li2S:P2S5:LiCl:LiBr are weighed according to the stoichiometric ratio of 4:1:1.6:1.4, put into a ball mill jar, add organic solvent n-heptane, seal, mill at a speed of 500 rpm for 24 h, obtain a uniformly mixed precursor solution, dry the precursor solution at 100℃ for 12 h to obtain an electrolyte precursor. The electrolyte precursor is added to a xylene solution with a siloxane concentration of 2%, stirred at 80℃ for 12 h to obtain a siloxane uniformly coated electrolyte precursor solution, which is dried at 100℃ for 24 h to obtain a dried siloxane coated electrolyte precursor, and the siloxane coated electrolyte precursor is sintered at 450℃ for 12 h under an argon atmosphere to obtain a silicon dioxide coated and doped Li 5.5 PS 4.5 Cl 0.8 Br 0.7 sulfide solid state electrolyte. The silicon dioxide coated and doped Li 5.5 PS 4.5 Cl 0.8 Br 0.7 sulfide solid state electrolyte prepared is tested by SEM and coating layer thickness, and the test results are shown in FIG. 1 and FIG. 2.

[0080] As can be seen from the SEM image in FIG. 1, the silicon dioxide coated and doped Li 5.5 PS 4.5 Cl 0.8 Br 0.7 sulfide solid state electrolyte can be obtained by using the scheme in the embodiment; as can be seen from the TEM image in FIG. 2, the thickness of the silicon dioxide coating layer on the silicon dioxide coated and doped Li 5.5 PS 4.5 Cl 0.8 Br 0.7 sulfide solid state electrolyte prepared by the method in the embodiment meets the requirements.

[0081] Example Two

[0082] The difference from Example One is that the siloxane concentration in the xylene solution is controlled to be 3%, and other conditions are the same as in Example One. The specific preparation process is as follows:

[0083] The electrolyte raw materials Li2S:P2S5:LiCl:LiBr were weighed according to the stoichiometric ratio of 4:1:1.6:1.4, placed in a ball mill jar, and sealed with the addition of an organic solvent n-heptane. The mixture was ball milled at a speed of 500 rpm for 24 h to obtain a uniformly mixed precursor solution. The precursor solution was dried at 100°C for 12 h to obtain an electrolyte precursor. The electrolyte precursor was added to a xylene solution with a siloxane concentration of 3%, and stirred at 80°C for 12 h to obtain a siloxane uniformly coated electrolyte precursor solution. The solution was dried at 100°C for 24 h to obtain a dried siloxane coated electrolyte precursor. The siloxane coated electrolyte precursor was sintered at 450°C for 12 h under an argon atmosphere to obtain a Li 5.5 PS 4.5 Cl 0.8 Br 0.7 sulfide solid-state electrolyte.

[0084] Example Three

[0085] The difference between Example One and Example Three is that the siloxane concentration in the xylene solution is controlled to be 4%, and other conditions are the same as in Example One. The specific preparation process is as follows:

[0086] The electrolyte raw materials Li2S:P2S5:LiCl:LiBr were weighed according to the stoichiometric ratio of 4:1:1.6:1.4, placed in a ball mill jar, and sealed with the addition of an organic solvent n-heptane. The mixture was ball milled at a speed of 500 rpm for 24 h to obtain a uniformly mixed precursor solution. The precursor solution was dried at 100°C for 12 h to obtain an electrolyte precursor. The electrolyte precursor was added to a xylene solution with a siloxane concentration of 4%, and stirred at 80°C for 12 h to obtain a siloxane uniformly coated electrolyte precursor solution. The solution was dried at 100°C for 24 h to obtain a dried siloxane coated electrolyte precursor. The siloxane coated electrolyte precursor was sintered at 450°C for 12 h under an argon atmosphere to obtain a Li 5.5 PS 4.5 Cl 0.8 Br 0.7 sulfide solid-state electrolyte.

[0087] Comparative Example One

[0088] Comparative Example One corresponds to the above-mentioned examples, and the difference between Comparative Example One and Example One is that the siloxane concentration in the xylene solution is controlled to be 0, and other conditions are the same as in Example One. The specific preparation process is as follows:

[0089] The electrolyte raw materials Li2S:P2S5:LiCl:LiBr were weighed according to the stoichiometric ratio of 4:1:1.6:1.4, placed in a ball mill jar, and sealed with the addition of an organic solvent n-heptane. The mixture was ball milled at a speed of 500 rpm for 24 h to obtain a uniformly mixed precursor solution. The precursor solution was dried at 100°C for 12 h to obtain an electrolyte precursor. The electrolyte precursor was added to a pure xylene solution and stirred at 80°C for 12 h. The solution was heated to 100°C and dried for 24 h to obtain an electrolyte precursor without any coating. The electrolyte precursor was sintered at 450°C for 12 h under an argon atmosphere to obtain a Li 5.5 PS 4.5 Cl 0.8 Br 0.7 sulfide solid-state electrolyte.

[0090] Comparative Example Two

[0091] The difference from Example One is that sintering was not performed, and the other conditions were the same as in Example One. The specific preparation process is as follows:

[0092] The electrolyte raw materials Li2S:P2S5:LiCl:LiBr were weighed according to the stoichiometric ratio of 4:1:1.6:1.4, placed in a ball mill jar, and sealed with the addition of an organic solvent n-heptane. The mixture was ball milled at a speed of 500 rpm for 24 h to obtain a uniformly mixed precursor solution. The precursor solution was dried at 100°C for 12 h to obtain an electrolyte precursor. The electrolyte precursor was added to a xylene solution with a siloxane concentration of 2% and stirred at 80°C for 12 h to obtain a siloxane-coated electrolyte precursor solution. The solution was heated to 100°C and dried for 24 h to obtain a dried siloxane-coated sulfide solid-state electrolyte.

[0093] Comparative Example Three

[0094] The difference from Example One is that the concentration of siloxane in the xylene solution was 10%, and the other conditions were the same as in Example One. The specific preparation process is as follows:

[0095] The electrolyte raw materials Li2S:P2S5:LiCl:LiBr were weighed according to the stoichiometric ratio of 4:1:1.6:1.4, placed in a ball mill jar, and sealed with an organic solvent n-heptane. The mixture was ball milled at a speed of 500 rpm for 24 h to obtain a uniformly mixed precursor solution. The precursor solution was dried at 100 °C for 12 h to obtain an electrolyte precursor. The electrolyte precursor was added to a xylene solution with a silicone concentration of 10%, and stirred at 80 °C for 12 h to obtain a uniformly coated electrolyte precursor solution. The solution was dried at 100 °C for 24 h to obtain a dried silicone-coated electrolyte precursor. The silicone-coated electrolyte precursor was sintered at 450 °C for 12 h under an argon atmosphere to obtain a silicon dioxide-coated and doped Li 5.5 PS 4.5 Cl 0.8 Br 0.7 sulfide solid-state electrolyte.

[0096] The EIS impedance of the electrolyte obtained in the above examples and comparative examples was measured by assembling a blocked cell with carbon-coated aluminum foil on both sides. The test method was as follows: the assembled blocked cell was placed in a thermostat at 25 °C for 1 h to allow the temperature of the electrolyte inside the cell to reach 25 °C. The cell was connected to a Suzhou electrochemical workstation, and the constant voltage alternating current impedance was measured in the frequency range of 1 MHz to 1 Hz. The ionic conductivity of the prepared electrolyte was obtained by conversion, and the results are shown in Table 1.

[0097] The full solid-state lithium metal battery was assembled as follows: high-nickel ternary NCM811, the above-prepared sulfide electrolyte, conductive agent VGCF, and adhesive SBS were weighed according to a certain mass ratio, then added to isobutyl isobutyrate, and then placed in a pug mill to set the rotation speed for pugging. After pugging, the slurry was coated by a doctor blade to obtain a positive electrode sheet, which was then punched to obtain a positive electrode sheet with a diameter of 10 mm. 150 mg of the above-prepared electrolyte powder was placed in a PEEK mold with a diameter of 10 mm, and pressed by a tablet press at a pressure of 100 MPa for 1 min. Then, the prepared 10 mm positive electrode sheet was placed on one side, and the pressure was applied again by the tablet press at a pressure of 500 MPa for 10 min. Finally, a metal lithium negative electrode was placed on the other side of the obtained sheet, and a pressure of 20 MPa was applied for 1 min to prepare a full solid-state lithium metal battery. The cycle stability of the full solid-state lithium metal battery was verified by constant current charge and discharge cycle tests.

[0098] The test conditions were as follows: 300 mg of the prepared electrolyte powder was placed in a 10 L size drying dish with controllable humidity, and the humidity was controlled at 20%. After 24 h, the ionic conductivity of the electrolyte was measured, and the ionic conductivity retention rate of the electrolyte after exposure to air was calculated. The results are shown in Table 1.

[0099] Table 1 Comparison of the first cycle lithium extraction specific capacity and the first efficiency of half-cells in the examples and comparative examples

[0100] As can be seen from the data in Table 1, when the concentration of siloxane is 2% during the coating process, the thickness of the silica coating layer is only about 10 nm, which basically has no effect on the ionic conductivity of the electrolyte, and can significantly improve the air stability and lithium stability of the electrolyte, and improve the cycle stability of the full solid-state lithium metal battery. It can be found from Comparative Example 1 and Comparative Example 2 that after the siloxane is decomposed at high temperature to generate silica, the lithium stability of the electrolyte can be improved, thereby improving the cycle stability of the full battery. It can be found from Comparative Examples 1, 2, 3 and Comparative Example 3 that as the concentration of siloxane increases, the electrolyte has better air stability, and the ion conductivity retention rate is higher after being exposed to air, but a large amount of siloxane coating can significantly reduce the ion conductivity of the electrolyte itself. The appropriate silica coating not only does not reduce the ion conductivity of the electrolyte, but also improves the air stability and lithium stability of the electrolyte, thereby reducing the production cost and improving the cycle stability of the full solid-state lithium metal battery.

[0101] In one embodiment, a battery is provided, comprising a positive electrode, a negative electrode and an electrolyte prepared by the method described above.

[0102] The method for preparing the sulfide solid-state electrolyte comprises: configuring electrolyte raw materials according to the stoichiometric ratio in the chemical formula of the sulfide solid-state electrolyte precursor, adding a first solvent and performing ball milling to form a new electrolyte precursor; placing the new electrolyte precursor in a second solvent containing siloxane, heating and stirring to allow the siloxane to coat on the new electrolyte precursor to form an electrolyte precursor with siloxane; and sintering the electrolyte precursor with siloxane to obtain a doped and coated sulfide electrolyte.

[0103] In a specific embodiment, the method further comprises: configuring the electrolyte raw materials according to the stoichiometric ratio in the chemical formula of the sulfide solid-state electrolyte precursor, adding a first solvent, and performing ball milling to form a precursor solution; and heating and drying the precursor solution to obtain the new electrolyte precursor.

[0104] The specific limitations of the method for preparing the electrolyte in the battery using the sulfide solid-state electrolyte can be referred to the limitations of the method for preparing the sulfide solid-state electrolyte using the sulfide solid-state electrolyte precursor described above, which will not be repeated here.

[0105] While the preferred embodiments in the application have been described, additional modifications and changes can occur to those skilled in the art once they learn of the basic creative principles contained herein. Therefore, the above disclosure is intended to be taken as illustrative only and not as limiting the scope of the application. The appended claims are intended to cover all modifications and changes as fall within the true scope and spirit of the application.

[0106] Obviously, numerous modifications and variations of the present application are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

A sulfide solid electrolyte precursor characterized by The sulfide solid electrolyte precursor has a chemical formula of Li 6-m PS 5-m X 1+m ; 0 < m < 2.5; wherein the element X comprises one or more of fluorine, chlorine, bromine, and iodine. The sulfide solid electrolyte precursor according to claim 1, wherein 0 < m < 1 in the chemical formula of the sulfide solid electrolyte precursor. An electrolyte precursor with siloxane, characterized in that, The new electrolyte precursor particle and a siloxane coated on at least part of the surface of the new electrolyte precursor particle; The new electrolyte precursor includes Li 6-m PS 5-m X 1+m 0 < m < 2.5, and element X includes one or more of fluorine, chlorine, bromine, and iodine. The siloxane is Si n O n-1 H 2n+2 or (H2SiO) n n is an integer greater than or equal to 2. A method for producing a sulfide solid electrolyte using the sulfide solid electrolyte precursor according to claim 1 or 2, characterized by, The method comprises: The electrolyte raw materials are configured according to the stoichiometric ratio in the chemical formula of the sulfide solid electrolyte precursor, a first solvent is added, and ball milling is performed to form a new electrolyte precursor; The new electrolyte precursor is placed in a second solvent containing siloxane, heated and stirred to allow the siloxane to coat the new electrolyte precursor, and an electrolyte precursor with siloxane is formed; The electrolyte precursor with siloxane is sintered to obtain a sulfide solid electrolyte. The sulfide solid electrolyte production method according to claim 4, characterized by The method further comprises: The electrolyte raw materials are configured according to the stoichiometric ratio in the chemical formula of the sulfide solid electrolyte precursor, a first solvent is added, and ball milling is performed to form a precursor solution; The precursor solution is heated and dried to obtain the new electrolyte precursor. The sulfide solid electrolyte production method according to claim 5, characterized by The electrolyte raw materials comprise one or more of Li2S, P2S5, LiCl, LiBr, LiF, or LiI; The first solvent is an alkane solvent; The ball milling speed is 200 rpm to 800 rpm; The ball milling time is 10 h to 60 h; The drying temperature of the precursor solution is 60°C to 140°C; The drying time of the precursor solution is 8 h to 50 h. The sulfide solid electrolyte production method according to claim 4, characterized by The chemical formula of the siloxane is Si n O n-1 H 2n+2 or (H2SiO) n wherein n is an integer greater than or equal to 2; The mass concentration of siloxane in the second solvent is 1% to 9%; The second solvent is an aromatic hydrocarbon solvent. The sulfide solid electrolyte production method according to claim 4, characterized by The method further comprises: allowing the siloxane to coat the new electrolyte precursor and drying to form an electrolyte precursor with siloxane; The drying temperature is 60°C to 140°C; The drying time is 10 h to 50 h. The sulfide solid electrolyte production method according to claim 4, characterized by The method further comprises: The electrolyte precursor with siloxane is placed in a tube furnace with an inert gas atmosphere for sintering, a silicon dioxide coating layer is formed on the surface of the electrolyte, and silicon dioxide is doped in the electrolyte body phase to form the sulfide solid electrolyte; The thickness of the silicon dioxide coating layer is 1 nm to 500 nm; The inert gas comprises one or more of nitrogen, helium, neon, argon, krypton, xenon, or radon. The sulfide solid electrolyte production method according to claim 9, characterized by The sintering temperature is 300°C to 800°C. A battery comprising a positive electrode, a negative electrode, and an electrolyte, characterized by The electrolyte is prepared by the method of any one of claims 4 to 10.

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