A sulfide solid electrolyte that contains lithium, phosphorus, sulfur, chlorine and bromine, wherein in powder X-ray diffraction analysis using CuKα rays, it has a diffraction peak A at 2θ=25.2±0.5 deg and a diffraction peak B at 2θ=29.7±0.5 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 CuKα rays, it has a diffraction peak A at 2θ=25.2±0.5 deg and a diffraction peak B at 2θ=29.7±0.5 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.

The method of manufacturing a sulfide-based inorganic solid electrolyte material, including: (A) preparing a sulfide-based inorganic solid electrolyte material in a vitreous state; and (B) annealing the sulfide-based inorganic solid electrolyte material in the vitreous state using a heating unit. Step (B) includes a step (B1) of disposing the sulfide-based inorganic solid electrolyte material in the vitreous state in a heating space, a step (B2) of annealing the sulfide-based inorganic solid electrolyte material in the vitreous state disposed in the heating space while increasing a temperature of the heating unit from an initial temperature T.sub.0 to an annealing temperature T.sub.1, and a step (B3) of annealing the sulfide-based inorganic solid electrolyte material in the vitreous state disposed in the heating space at the annealing temperature T.sub.1, and a temperature increase rate from the initial temperature T.sub.0 to the annealing temperature T.sub.1 in the step (B2) is 2° C./min or higher.

A sulfide solid electrolyte contains a compound that has a crystal phase having an argyrodite-type crystal structure and that is represented by Li.sub.aPS.sub.bX.sub.c, where X is at least one elemental halogen, a represents a number of 3.0 or more and 6.0 or less, b represents a number of 3.5 or more and 4.8 or less, and c represents a number of 0.1 or more and 3.0 or less. The sulfide solid electrolyte has a ratio of A.sub.Li/(A.sub.Li+A.sub.P+A.sub.S+A.sub.X) to a specific surface area (m.sup.2 g.sup.−1) of 3.40 (m.sup.−2g) or more, where A.sub.Li represents the amount of lithium (atom %) quantitatively determined from the Li 1s peak, A.sub.P represents the amount of phosphorus (atom %) quantitatively determined from the P 2p peak, A.sub.S represents the amount of sulfur (atom %) quantitatively determined from the S 2p peak, and A.sub.X represents the amount of halogen (atom %) quantitatively determined from the halogen peak, the peaks being exhibited in X-ray photoelectron spectroscopy (XPS).

A method for producing a sulfide solid electrolyte includes: preparing a uniform solution that includes at least elemental lithium (Li), elemental tin (Sn), elemental phosphorus (P), and elemental sulfur (S) in an organic solvent; removing the organic solvent from the uniform solution to obtain a precursor; and heat-treating the precursor to obtain a sulfide solid electrolyte.

A solid electrolyte composition containing a sulfide-based solid electrolyte having conductivity of ions of metals belonging to Group I or II of the periodic table, a binder, and a dispersion medium, in which an amount of dissolved oxygen in the solid electrolyte composition is 20 ppm or less, a manufacturing method thereof, a storage method thereof, and a kit thereof, a solid electrolyte-containing sheet having a layer made of the solid electrolyte composition, a storage method thereof, and a kit thereof, and an all-solid state secondary battery.

A sulfide solid electrolyte may include lithium, phosphorus and sulfur, and the sulfide solid electrolyte may have a diffraction peak A at 2θ=25.2±0.5 deg and a diffraction peak B at 29.7±0.5 deg in powder X-ray diffraction using CuKα rays, and a crystallite diameter in a range of from 5 to 20 nm.

A sulfide solid electrolyte, which is able to adjust the morphology unavailable traditionally, or is readily adjusted so as to have a desired morphology, the sulfide solid electrolyte having a volume-based average particle diameter measured by laser diffraction particle size distribution measurement of 3 μm or more and a specific surface area measured by the BET method of 20 m2/g or more; and a method of treating a sulfide solid electrolyte including the sulfide solid electrolyte being subjected to at least one mechanical treatment selected from disintegration and granulation.

A sulfide solid electrolyte, which is able to adjust the morphology unavailable traditionally, or is readily adjusted so as to have a desired morphology, the sulfide solid electrolyte having a volume-based average particle diameter measured by laser diffraction particle size distribution measurement of 3 μm or more and a specific surface area measured by the BET method of 20 m2/g or more; and a method of treating a sulfide solid electrolyte including the sulfide solid electrolyte being subjected to at least one mechanical treatment selected from disintegration and granulation.

A sulfide-based solid electrolyte particle having a crystal phase of a cubic argyrodite-type crystal structure composed of Li, P, S and a halogen (Ha. The proposed sulfide-based solid electrolyte particle has a feature such that the ratio (Z.sub.Ha2/Z.sub.Ha1) of an element ratio Z.sub.Ha2 of the halogen (Ha) at the position of 5 nm in depth from the particle surface to an element ratio Z.sub.Ha1 of the halogen (Ha) at the position of 100 nm in depth from the particle surface is 0.5 or lower, as measured by XPS; and the ratio (Z.sub.O2/Z.sub.A2) of an element ratio Z.sub.O2 of oxygen to the total Z.sub.A2 of element ratios of phosphorus (P), sulfur (S), oxygen (O) and the halogen (Ha) at the position of 5 nm in depth from the particle surface is 0.5 or higher, as measured by XPS.