Disclosed is a method of manufacturing a solid electrolyte for an all-solid battery. The method may include preparing a solvent admixture comprising a first polar organic solvent containing a cyano group and a second polar organic solvent containing a hydroxyl group, preparing an electrolyte admixture by dissolving Li.sub.2S, P.sub.2S.sub.5 and LiCl in the solvent admixture, and preparing a solid electrolyte by stirring the electrolyte admixture. The method may further include precipitating the solid electrolyte by evaporating the solvent admixture, and heat treating the precipitated solid electrolyte. In particular, the solvent admixture may include the second polar organic solvent in an amount of about 0.01 to 0.03 wt % based on the total weight of the first polar organic solvent.

A sulfide solid electrolyte that contains lithium, phosphorus, sulfur, chlorine and bromine, wherein in powder X-ray diffraction analysis using CuK rays, it has a diffraction peak A at 2=25.20.5 deg and a diffraction peek B at 2=29.70.5 deg, the diffraction peak A and the diffraction peak B satisfy the following formula (A), and a molar ratio of the chlorine to the phosphorus c (Cl/P) and a molar ratio of the bromine to the phosphorus d (Br/P) satisfies the following formula (1):

1.2<c+d<1.9(1)

0.845<S.sub.A/S.sub.B<1.200(A) where S.sub.A is an area of the diffraction peak A and S.sub.B is an area of the diffraction peak B.

A sulfide solid electrolyte that contains lithium, phosphorus, sulfur, chlorine and bromine, wherein in powder X-ray diffraction analysis using CuK rays, it has a diffraction peak A at 2=25.20.5 deg and a diffraction peek B at 2=29.70.5 deg, the diffraction peak A and the diffraction peak B satisfy the following formula (A), and a molar ratio of the chlorine to the phosphorus c (Cl/P) and a molar ratio of the bromine to the phosphorus d (Br/P) satisfies the following formula (1):

1.2<c+d<1.9(1)

0.845<S.sub.A/S.sub.B<1.200(A) where S.sub.A is an area of the diffraction peak A and S.sub.B is an area of the diffraction peak B.

Provided is a sulfide-based solid electrolyte comprising lithium, phosphorus, sulfur, and a halogen, as a novel solid electrolyte capable of suppressing generation of hydrogen sulfide and securing ionic conductivity. The solid electrolyte is characterized by comprising Li.sub.7aPS.sub.6aHa.sub.a (wherein Ha represents a halogen, and a satisfies 0.2<a1.8) having an argyrodite-type crystal structure, and Li.sub.3PS.sub.4, wherein, in an X-ray diffraction (XRD) pattern obtained through measurement by an X-ray diffraction method, the ratio of the peak intensity of a peak appearing at a position in a range of diffraction angle 2=26.0 to 28.8 derived from Li.sub.3PS.sub.4, relative to the peak intensity of a peak appearing at a position in a range of diffraction angle 2=24.9 to 26.3 derived from the argyrodite-type crystal structure, is 0.04 to 0.3.

Sulfide-type compound particles microparticulated, having an argyrodite-type crystal structure, and including lithium (Li), phosphorus (P), sulfur (S), and a halogen (Ha). As sulfide-type compound particles that can inhibit generation of hydrogen sulfide gas even upon contact with moisture in the atmosphere, provided are sulfide-type compound particles having D50 in a volume-basis particle size distribution of 50 m or less and having an occupancy of sulfur (S) and the halogen (Ha) in the S3 (4a) site, as calculated by a neutron diffraction measurement, of 85% or more.

Provided is a method for producing an alkali metal halide, including causing a reaction of an alkali metal sulfide and a substance represented by the following general formula (1) in the absence of a solvent or in a solvent except for water: X.sub.2 (1), wherein X represents a halogen element.

An aspect of the present invention is a sulfide solid electrolyte that contains at least one element M selected from the group consisting of Al, Si, B, Mg, Zr, Ti, Hf, Ca, Sr, Sc, Ce, Ta, Nb, W, Mo, and V, and N and has a crystalline structure. Another aspect of the present invention is a sulfide solid electrolyte that contains Al and N and that has a crystalline structure.

A sulfide glass solid electrolyte sheet can be protected from reaction with moisture by a thin metal layer coating converted to a thin electrochemically functional and protective compound layer. The converted protective compound layer is electrochemically functional in that it allows for through transport of lithium ions.

A sulfide-based solid electrolyte contains a nickel (Ni) element and a halogen element. For example, a sulfide-based solid electrolyte can include, with respect to 100 parts by mole of a mixture of lithium sulfide (Li.sub.2S) and diphosphorus pentasulfide (P.sub.2S.sub.5), 5 parts by mole to 20 parts by mole of nickel sulfide (Ni.sub.3S.sub.2), and 5 parts by mole to 40 parts by mole of lithium halide.

A sulfide-based solid electrolyte contains a nickel (Ni) element and a halogen element. For example, a sulfide-based solid electrolyte can include, with respect to 100 parts by mole of a mixture of lithium sulfide (Li.sub.2S) and diphosphorus pentasulfide (P.sub.2S.sub.5), 5 parts by mole to 20 parts by mole of nickel sulfide (Ni.sub.3S.sub.2), and 5 parts by mole to 40 parts by mole of lithium halide.