A main object of the present disclosure is to provide a sulfide solid electrolyte with excellent water resistance. The present disclosure achieves the object by providing a sulfide solid electrolyte including a LGPS type crystal phase, and containing Li, Ge, P, and S, wherein: when an X-ray photoelectron spectroscopy measurement is conducted to a surface of the sulfide solid electrolyte, a proportion of Ge.sup.2+ with respect to total amount of Ge is 20% or more.

A solid electrolyte material may be advantageously synthesized using a multipart solvent/solution based method employing selective solvation and/or particle size reduction for different reactants used to form the solid electrolyte.

As a novel sulfide compound having a low elastic modulus while retaining high ion conductivity, a sulfide compound for a solid electrolyte of a lithium secondary battery that includes a crystal phase of a cubic argyrodite type crystal structure, and is represented by the compositional formula: Li.sub.7−xPS.sub.6−xCl.sub.yBr.sub.z, wherein x in the compositional formula satisfies x=y+z and 1.0<x≤1.8, and a ratio, z/y, of the molar ratio of Br to the molar ratio of Cl is from 0.1 to 10.0.

A solid electrolyte material comprises Li, T, X and A wherein T is at least one of P, As, Si, Ge, Al, Sb, W, and B; X is one or more halogens and/or N; A is one or more of S or Se. The solid electrolyte material has peaks at 14.9°±0.50°, 20.4°±0.50°, and 25.4°±0.50° in X-ray diffraction measurement with Cu—Kα(1,2)=1.5418A and may include glass ceramic and/or mixed crystalline phases.

Provided is a method for producing a sulfide solid electrolyte having a high purity as side reaction hardly occurs, and having a high ionic conductivity, in a simplified manner.

The method is for producing a sulfide solid electrolyte containing a lithium atom, a sulfur atom, a phosphorus atom and a halogen atom, comprising separately preparing a complex (1) containing a sulfide that contains a lithium atom, a sulfur atom and a phosphorus atom, as a constituent element, and a complex (2) containing a halide that contains a lithium atom and a halogen atom, as a constituent element, and mixing the complex (1) and the complex (2).

A solid ion conductor compound including Li, Ho, and a halogen element, wherein the compound has diffraction peaks at 30°2θ to 33°2θ, 33°2θ to 36°2θ, 40°2θ to 44°2θ, and 48°2θ to 52°28θ, when analyzed using CuKα radiation, and wherein a full width at half maximum of at least one peak at 40°2θ to 44°2θ is 0.3°2θ or greater.

The present application provides a preparation method for a solid electrolyte, including: acquiring an initial reaction mixture including a lithium precursor, a central atom ligand and an organic solvent; acquiring a modified solution including a borate ester and the organic solvent; mixing the initial reaction mixture and the modified solution, and drying to acquire an initial product; performing a grinding, cold press and heat treatment to the initial product to obtain the solid electrolyte. In the preparation method provided by the present application, a B and O co-doped sulphide solid electrolyte can be obtained by modifying the sulphide solid electrolyte with the borate ester as a doping raw material. The ionic conductivity of the prepared sulphide solid electrolyte is significantly improved, which is also conducive to improvement of energy density of the all-solid-state batteries.

Disclosed herein are a solid ion conductor compound includinga compound that is represented by Formula 1 and has an argyrodite-type crystal structure, an ion conductivity of 3 mS/cm or more at 25° C., and an average particle diameter of 0.1 .Math.m to 7 .Math.m, a solid electrolyte including the solid ion conductor compound, an electrochemical cell including the solid ion conductor compound, and a method of preparing the solid ion conductor compound.

##STR00001##

In Formula 1, M1 is at least one metal element selected from Group 1 to 15 elements, except for Li, in the Periodic Table, M2 is at least one element selected from Group 17 elements in the Periodic Table, M3 isSO.sub.n, and 4≤a≤8, 0≤x<1, 3≤y≤7, 0<z≤2, 0≤w<2, 1.5≤n≤5, and 0<x+w<3.

A method of preparing a solid electrolyte and an all-solid battery including a solid electrolyte prepared by the method, the method including: contacting a first solvent and a first starting material comprising an alkali metal, sulfur, phosphorus, an element M, or a combination thereof to form a first solution; precipitating a first precursor from the first solution; contacting a second solvent, the first precursor, and a second starting material comprising an alkali metal, sulfur, phosphorus, an element M, or a combination thereof to form a second solution; precipitating a second precursor from the second solution; and heat treating the second precursor to prepare the solid electrolyte, wherein the element M comprises an element of Group 14 of the Periodic Table of the Elements, and the element M and the alkali metal in the first starting material and the second starting material are the same or different.

A method of preparing a solid electrolyte and an all-solid battery including a solid electrolyte prepared by the method, the method including: contacting a first solvent and a first starting material comprising an alkali metal, sulfur, phosphorus, an element M, or a combination thereof to form a first solution; precipitating a first precursor from the first solution; contacting a second solvent, the first precursor, and a second starting material comprising an alkali metal, sulfur, phosphorus, an element M, or a combination thereof to form a second solution; precipitating a second precursor from the second solution; and heat treating the second precursor to prepare the solid electrolyte, wherein the element M comprises an element of Group 14 of the Periodic Table of the Elements, and the element M and the alkali metal in the first starting material and the second starting material are the same or different.