The present disclosure provides a method for making a solid-state argyrodite electrolyte represented by Li.sub.6PS.sub.5X (where X is selected from chloride, bromide, iodine, or a combination thereof) having an ionic conductivity greater than or equal to about 1.0×10.sup.−4 S/cm to less than or equal to about 10×10.sup.−3 S/cm at about 25° C. The method may include contacting a first suspension and a first solution to form a precursor, where the first suspension is a Li.sub.3PS.sub.4 suspension including an ester solvent and the first solution is a Li.sub.2S and LiX (where X is selected from chloride, bromide, or iodine, or a combination thereof) solution including an alcohol solvent; and removing the ester solvent and the alcohol solvent from the precursor to form the solid-state argyrodite electrolyte.

An electrochemical device includes a positive electrode, a negative electrode, and an electrolyte having lithium ion conductivity. The positive electrode includes a positive current collector and a positive electrode mixture layer supported on the positive current collector. The positive electrode mixture layer contains a positive electrode active material reversibly doped with an anion. The negative electrode includes a negative current collector and a negative electrode mixture layer supported on the negative current collector. The negative electrode mixture layer contains a negative electrode active material reversibly doped with lithium ions. The negative electrode active material contains non-graphitizable carbon. A ratio Mp/Mn of a mass Mp of the positive electrode active material supported on a unit area of the positive electrode to a mass Mn of the negative electrode active material supported on a unit area of the negative electrode is in a range from 1.1 to 2.5, inclusive.

A unit stack-cell structure and an all-solid-state secondary battery including the same, the unit stack-cell structure includes a plurality of stacked unit cells, each unit cell of the plurality of stacked unit cells including a laminate in which a cathode layer; a solid electrolyte layer; an anode layer; and an elastic layer are sequentially arranged, wherein the elastic layer has a compressive strength of greater than or equal to about 0.28 MPa and less than about 0.6 MPa in a compressibility interval in a range of about 40% to about 70%.

There is provided an electrode layer for an all-solid state battery, which contains an electrode active material and a sulfide solid electrolyte, where the sulfide solid electrolyte has an average particle diameter of less than 1 .Math.m and the electrode layer contains an imidazoline-based dispersion material.

A solid electrolyte includes lithium, phosphorus, sulfur, and halogen, in which, when the solid electrolyte is measured by TG-MS, a first peak derived from cyclic sulfur appears in a temperature range of 170° C. or higher and lower than 250° C., a second peak derived from the cyclic sulfur appears in a temperature range of 250° C. or higher and lower than 300° C., and a peak intensity P1 of the first peak is higher than a peak intensity P2 of the second peak.

A solid electrolyte material contains Li, M, and X. M is at least one selected from metallic elements, and X is at least one selected from the group consisting of Cl, Br, and I. A plurality of atoms of X form a sublattice having a closest packed structure. An average distance between two adjacent atoms of X among the plurality of atoms of X is 1.8% or more larger than a distance between two adjacent atoms of X in a rock-salt structure composed only of Li and X.

Provided is a method for producing a sulfide-based solid electrolyte with a balance between the ion conductivity of the sulfide-based solid electrolyte and the heat generation amount of an electrode layer containing the sulfide-based solid electrolyte during an electrode reaction. Disclosed is a method for producing a sulfide-based solid electrolyte comprising a sulfide glass-based material that contains at least one lithium halide compound selected from the group consisting of LiI, LiBr and LiCl, the method comprising immersing the sulfide glass-based material, which is at least one sulfide glass-based material selected from the group consisting of a sulfide glass and a glass ceramic, in an organic solvent having a solubility parameter of 7.0 or more and 8.8 or less, for 1 hour to 100 hours.

In a method for recycling all solid-state batteries, spent battery cells are dissolved in anhydrous ethanol. The resulting solution is separated into solids and supernatants which are separately processed to regenerate the solid electrolyte and the solid electrode materials. The supernatant is subjected to vacuum evaporation to precipitate an electrolyte powder, which is then annealed under flowing oxygen. The solid electrode material is regenerated by washing the solids with water, drying the washed solids, relithiating the washed solids, and annealing the relithiated solids. The resulting materials are suitable for use in fabrication of new all-solid state batteries.

The solid electrolyte material consists essentially of Li, Ti, M, and F. Here, M is at least one selected from the group consisting of Mg and Ca.

The solid electrolyte material consists essentially of Li, Ti, Al, M, and F. Here, M is at least one selected from the group consisting of Zr and Mg.