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 method for removing alkali metal from a hydrocarbon feedstock comprising alkali metal, non-alkali metal and sulfur. The method includes separating out at least a portion of any alkali metal sulfide and a portion of any non-alkali metal from the hydrocarbon feedstock. Hydrogen sulfide can be added to the remaining hydrocarbon feedstock to form alkali hydrosulfide from any alkali metal remaining in the hydrocarbon feedstock. The alkali hydrosulfide is then separated from the hydrocarbon feedstock. Alkali metal may be removed from the alkali metal sulfide separated out from the hydrocarbon feedstock. Alkali hydrosulfide may be treated to form alkali metal sulfide, and alkali metal may also be removed from the formed alkali metal sulfide.

Methods for wet chemical synthesis of lithium argyrodites are provided, which in some embodiments include includes dissolving a stoichiometric mixture of precursors in a small quantity of solvent in an argon atmosphere, drying the mixture under vacuum or an inert gas atmosphere to evaporate the solvent, and then annealing to obtain a final lithium argyrodite product. Further embodiments comprise synthesizing the precursors, and excess halide doping to achieve higher ionic conductivity.

Methods for wet chemical synthesis of lithium argyrodites are provided, which in some embodiments include includes dissolving a stoichiometric mixture of precursors in a small quantity of solvent in an argon atmosphere, drying the mixture under vacuum or an inert gas atmosphere to evaporate the solvent, and then annealing to obtain a final lithium argyrodite product. Further embodiments comprise synthesizing the precursors, and excess halide doping to achieve higher ionic conductivity.

A main object of the present disclosure is to provide a sulfide solid electrolyte having excellent ion conductivity and water resistance. The present disclosure achieves the object by providing a sulfide solid electrolyte comprising Li, P, S and CO.sub.3.sup.2−; wherein the sulfide solid electrolyte includes a crystal phase with Li.sub.7P.sub.3S.sub.11 structure as a main phase; in an X-ray diffraction measurement using a CuKα ray, when I.sub.A designates a peak intensity of Li.sub.2S that appears at the position of 2θ=27.0°±0.5°, and I.sub.B designates a peak intensity of the crystal phase that appears at the position of 2θ=23.65°±0.50°, I.sub.A/I.sub.B is 0 or more and 0.39 or less; and a peak of a heterogeneous phase that appears at the position of 2θ=16.5°±0.5° is not included.

Nanosized lithium phosphate sulfide solid state electrolytes are synthesized by a facile method using ethyl acetate as the solvent. SSE compositions comprising nanosized lithium phosphate sulfide synthesized using the methods include particles having an average diameter of from 50 nm to 1000 nm. The nanosized lithium phosphate sulfide has a formula Li.sub.xP.sub.yS.sub.z, wherein 3≤x ≤7, 1≤y≤3, and 4≤z≤11.

[Problem] To provide a method for efficiently producing a sulfide solid electrolyte using a liquid-phase method.

[Solution to Problem] A method for producing a sulfide solid electrolyte not using a pulverizer in reacting raw materials, wherein a raw material that contains lithium sulfide, a phosphorus compound and a halogen compound, and a complexing agent are stirred in a reactor while a fluid that contains the contents in the reactor is discharged outside the reactor through a discharging port arranged in the reactor and the fluid that contains the discharged contents is returned back to the reactor through a returning port arranged in the reactor to thereby make the contents-containing fluid circulate therethrough.

As a novel sulfide compound having a low elastic modulus while retaining the high ion conductivity, a sulfide compound for a solid electrolyte of a lithium secondary battery that includes a crystal phase of a cubic argyrodite type crystal structure, and is represented by the compositional formula: Li.sub.7−xPS.sub.6−xCl.sub.yBr.sub.z, wherein x in the compositional formula satisfies x=y+z and 1.0<x≤1.8, and a ratio (z/y) of the molar ratio of Br to the molar ratio of Cl is from 0.1 to 10.0 is proposed.

The disclosure is directed to a sulfidizing agent obtainable by mixing M.sub.yS.sub.x and ZSH in a weight ratio of from about 90:10 to about 10:90, wherein M is chosen from Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+, Cs.sup.+, NH.sub.4.sup.+, Mg.sup.2+ and Ca.sup.2+, y is about 1 or about 2, x is from about 1.1 to about 5, and Z is independently chosen from Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+, Cs.sup.+ and NH.sub.4.sup.+, and a process for using the sulfidizing agent in the recovery of one or more metal ores and/or polymetallic minerals from gangue.