The present technology relates to inorganic compounds having an argyrodite-type structure based on an alkali metal obtained by a preparation process comprising a step of grinding the sulfide of the alkali metal, the sulfate of the alkali metal, phosphorus pentasulfide and a halide of the alkali metal. Also described are electrode materials, electrodes, electrolytes comprising said inorganic compound having an argyrodite-type structure and their uses in electrochemical cells, for example, in electrochemical accumulators, particularly in all-solid-state batteries.