There is provided a solid electrolyte composition containing an inorganic solid electrolyte having ion conductivity of a metal belonging to Group 1 or Group 2 in the periodic table and a binder containing non-spherical binder particles consisting of secondary particles formed of primary particles having an average particle size of 1 to 1,000 nm. There are also provided an all-solid state secondary battery, an electrode sheet for an all-solid state secondary battery, and an all-solid state secondary battery, which have a layer constituted of this composition.

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.

Set forth herein are A(LiBH.sub.4)(1−A)(P.sub.2S.sub.5) wherein 0.05<A≤0.95 compositions that are suitable for use as solid state bonding layer in lithium electrochemical devices. Also set forth herein are novel and inventive methods of making the A(LiBH.sub.4)(1−A) (P.sub.2S.sub.5) compositions while utilizing scalable and commercial methods. Similarly, disclosed herein are novel electrochemical devices which incorporate these and other composite A(LiBH.sub.4)(1−A)(P.sub.2S.sub.5) compositions or materials.

The present invention relates to a method for preparing a sulfide-based solid electrolyte, a sulfide-based solid electrolyte prepared by the method, and an all-solid-state lithium secondary battery including the sulfide-based solid electrolyte. The method of the present invention includes a) mixing Li.sub.2S with P.sub.2S.sub.5 to prepare a mixed powder, b) placing the mixed powder, an ether, and stirring balls in a container, sealing the container, followed by stirring to prepare a suspension, and c) stirring the suspension under high-temperature and high-pressure conditions to prepare sulfide-based solid particles.

Provided is a solid electrolyte having a high ion conductivity and excellent in battery performance not going through a step of removing water such as a drying step, while simplifying the production process and reducing the production cost. Specifically, provided is a method for producing a sulfide-based solid electrolyte, including causing a reaction of an alkali metal sulfide and a specific substance in a solvent.

Provided is a solid electrolyte having a high ion conductivity and excellent in battery performance not going through a step of removing water such as a drying step, while simplifying the production process and reducing the production cost. Specifically, provided is a method for producing a sulfide-based solid electrolyte, including causing a reaction of an alkali metal sulfide and a specific substance in a solvent.

A method for producing a sulfide solid electrolyte according to an embodiment of the present invention is a method for producing a sulfide solid electrolyte, including: preparing a composition containing P, S, N, an element A, and an element M; reacting the composition to obtain an intermediate; and heating the intermediate to obtain a sulfide solid electrolyte, where the composition includes a raw material compound containing N, the element A, and the element M. A represents at least one element selected from the group consisting of Li, Na, and K. M represents at least one element selected from the group consisting of Al, Ta, Si, Sc, Mg, Nb, B, Hf, C, P, Zr, and Ti.

A solid electrolyte according to the present disclosure includes first particles consisted of a first solid electrolyte material and second particles consisted of a second solid electrolyte material. The first solid electrolyte material has a higher ionic conductivity than the second solid electrolyte material. The second solid electrolyte material has a lower Young's modulus than the first solid electrolyte material.

A novel sulfide solid electrolyte containing Li, P, S, and a halogen, which can be used as a solid electrolyte for a lithium secondary battery or the like, and is able to suppress the generation of a hydrogen sulfide gas even when exposed to moisture in the atmosphere. The sulfide solid electrolyte comprises a crystal phase or a compound having an argyrodite-type structure and containing Li, P, S, and a halogen; and a compound composed of Li, Cl, and Br and having a peak at each position of 2θ=29.1°±0.5° and 33.7°±0.5° in an X-ray diffraction pattern.