A sulfide solid electrolyte material with favorable reduction-resistance has a second structural part formed to cover a plurality of first structural parts, a first ion conductor composing the first structural part has a specific crystal phase with favorable ion conductivity, and a weight ratio γ of an Me element to a P element in the second structural part is less than 0.72.

A sulfide solid electrolyte material with favorable reduction-resistance has a second structural part formed to cover a plurality of first structural parts, a first ion conductor composing the first structural part has a specific crystal phase with favorable ion conductivity, and a weight ratio γ of an Me element to a P element in the second structural part is less than 0.72.

A solid electrolyte contains a thio-LISICON Region II-type crystal structure, where the solid electrolyte does not contain P.sub.2S.sub.6.sup.4− structure. A solid electrolyte, where:

(1) a signal of a thio-LISICON Region II-type crystal structure is observed in the solid .sup.31P-NMR spectrometry, and

(2) a signal of a P.sub.2S.sub.6.sup.4− structure is not observed in the solid .sup.31P-NMR spectrometry.

The present disclosure provides a solid electrolyte material having a high lithium ion conductivity. The solid electrolyte material according to the present disclosure includes Li, Zr, Y, W, and X. X is at least one element selected from the group consisting of Cl and Br.

The present invention is to provide a heteroatom-doped nanodiamond, the heteroatom-doped nanodiamond being doped with at least one heteroatom, the heteroatom-doped nanodiamond satisfying criteria (i) and/or (ii) below: (i) a BET specific surface area being from 20 to 900 m.sup.2/g, and (ii) an average size of primary particles being from 2 to 70 nm.

An inorganic solid electrolyte-containing composition contains an inorganic solid electrolyte having an ion conductivity of a metal belonging to Group 1 or Group 2 in the periodic table, a polymer binder, and a dispersion medium, where the polymer binder includes a polymer binder of which an adsorption rate with respect to the inorganic solid electrolyte in the dispersion medium is less than 60%.

There is provided an inorganic solid electrolyte-containing composition containing an inorganic solid electrolyte, a polymer binder, and a dispersion medium having an SP value of 15 to 21 MPa.sup.1/2, in which the binder includes a polymer binder consisting of a styrene-ethylene-butylene-styrene copolymer in which a content of a styrene constitutional component is more than 0% by mole and less than 50% by mole, the adsorption rate of the polymer binder with respect to the inorganic solid electrolyte is less than 60%. There are also provided a sheet for an all-solid state secondary battery and an all-solid state secondary battery, in which this inorganic solid electrolyte-containing composition is used, and manufacturing methods for a sheet for an all-solid state secondary battery, and an all-solid state secondary battery.

A sulfide solid electrolyte particles comprising lithium, phosphorus and sulfur, having a volume-based average particle size measured by laser diffraction particle size distribution measurement of 0.1 μm to 10 μm, having a diffraction peak having 2θ of 29.0 to 31.0 deg in powder X-ray diffraction measurement using CuKα ray, and an intensity ratio (Ib/Ip) of a peak intensity Ib at a high angle-side low part of the diffraction peak to a peak intensity Ip of the diffraction peak is less than 0.09.

A sulfide solid electrolyte particles comprising lithium, phosphorus and sulfur, having a volume-based average particle size measured by laser diffraction particle size distribution measurement of 0.1 μm to 10 μm, having a diffraction peak having 2θ of 29.0 to 31.0 deg in powder X-ray diffraction measurement using CuKα ray, and an intensity ratio (Ib/Ip) of a peak intensity Ib at a high angle-side low part of the diffraction peak to a peak intensity Ip of the diffraction peak is less than 0.09.

The solid electrolyte of the present disclosure includes at least one compound selected from a group including (A) a compound in which a part of Li atom in Li.sub.3PS.sub.4 is substituted with a polyvalent atom (provided that Mg is excluded); (B) a compound in which a part of Li atom in Li.sub.6PS.sub.5X (X: Cl, Br or I) is substituted with a polyvalent atom; and (C) a compound in which a part of Li atom in Li.sub.7P.sub.3S.sub.11 is substituted with a polyvalent atom.