A negative electrode active material of the present disclosure includes: a graphite particle having a void inside; and a first solid electrolyte. The void has a void size of 1 nm or more and 300 nm or less. The first solid electrolyte is present in the void. The graphite particle has, for example, a plurality of voids inside. The graphite particle has an average void size, determined by a mercury intrusion method, of, for example, 1 nm or more and 300 nm or less.

A method for producing an LGPS-type solid electrolyte can be provided, the method includes preparing a homogeneous solution by mixing and reacting Li.sub.2S and P.sub.2S.sub.5 in an organic solution such that the molar ratio of Li.sub.2S/P.sub.2S.sub.5 is 1.0-1.85; forming a precipitate by adding, to the homogeneous solution, at least one MS.sub.2 (M is selected from the group consisting of Ge, Si, and Sn) and Li.sub.2S and then mixing; obtaining a precursor by removing the organic solution from the precipitate; and obtaining the LGPS-type solid electrolyte by heating the precursor at 200-700° C.

A process for producing a low-cost water-reactive metal sulfide material includes dissolving a substantially anhydrous alkali metal salt and a substantially anhydrous sulfide compound in a substantially anhydrous polar solvent, providing differential solubility for a substantially high solubility alkali metal sulfide and a substantially low solubility by-product, and forming a mixture of the high solubility alkali metal sulfide and the low solubility by-product; separating the low solubility by-product from the mixture to isolate the supernatant including the alkali metal sulfide, and separating the polar solvent from the alkali metal sulfide to produce the alkali metal sulfide. The present invention provides a scalable process for production of a high purity alkali metal sulfide that is essentially free of undesired by-products.

A process for producing a low-cost water-reactive metal sulfide material includes dissolving a substantially anhydrous alkali metal salt and a substantially anhydrous sulfide compound in a substantially anhydrous polar solvent, providing differential solubility for a substantially high solubility alkali metal sulfide and a substantially low solubility by-product, and forming a mixture of the high solubility alkali metal sulfide and the low solubility by-product; separating the low solubility by-product from the mixture to isolate the supernatant including the alkali metal sulfide, and separating the polar solvent from the alkali metal sulfide to produce the alkali metal sulfide. The present invention provides a scalable process for production of a high purity alkali metal sulfide that is essentially free of undesired by-products.

The present invention relates to a solid electrolyte, its precursor, methods for producing the same as well as its use, e.g. in electrochemical cells or capacitors, fuel cells, batteries, and sensors.

A blower (100) blows inert gas. A crusher (200) repeats vitrifying plural kinds of inorganic compounds (A1) by mechanical energy and blowing up the plural kinds of vitrified inorganic compounds (A1) by the inert gas blown from the blower (100). At least some of the plural kinds of inorganic compounds (A1) blown up by the inert gas enter into a first collector (300). The first collector (300) returns the at least some of the plural kinds of inorganic compounds to the crusher (200). A system (S) (for example, a pipe (Pa), a buffer tank (110), a pipe (Pb), a pipe (Pc), and a pipe (Pi) described below) circulates the inert gas from the blower (100) through the crusher (200) and the first collector (300) to the blower (100).

The positive electrode active material of the present disclosure includes a complex oxide represented by formula (1): LiNi.sub.xMe.sub.1-xO.sub.2 as a main component and has a hydrogen element content of 238.8 ppm by mass or less. Here, x satisfies 0.5≤x≤1, and Me is at least one element selected from the group consisting of Mn, Co, and Al.

The present invention relates to a solid electrolyte, its precursor, methods for producing the same as well as its use, e.g. in electrochemical cells and capacitors, fuel cells, batteries and sensors.

A method of producing an inorganic material (S10) according to the present invention includes a vitrification step (S12) of applying shearing stress and compressive stress to a mixed powder (MP) of a plurality of kinds of inorganic compound powders by using a ring ball mill mechanism (70) to vitrify at least a part of the mixed powder (MP); and a dispersion step (S13) of dispersing the vitrified mixed powder (MP) after the vitrification step (S12), where a combined step of the vitrification step (S12) and the dispersion step (S13) is performed a plurality of times to obtain a vitrified inorganic material powder from the mixed powder.

A method for synthesizing solid-state electrolytes and for synthesizing precursors for solid-state electrolytes by plasma-processing.