TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: Particles of dissimilar material are formed on surface of main component of positive-electrode active-material particles. Preferred Composition: The positive-electrode active-material particles comprise secondary particles (23) to which primary particles (22) are adhered. The metal of dissimilar material is zirconium, tungsten, titanium and/or silicon. The amorphous solid electrolyte is sulfide-type solid electrolyte containing lithium sulfide-silicon sulfide, lithium iodide-lithium sulfide-silicon sulfide, lithium iodide-lithium sulfide-phosphorus sulfide, lithium iodide-lithium sulfide-boron sulfide, lithium phosphate-lithium sulfide-silicon sulfide (Li3PO4-Li2S-Si2S, LiPO4-Li2S-SiS), lithium iodide-lithium sulfide-phosphorus pentoxide and/or lithium iodide-lithium phosphate-phosphorus pentasulfide. The reaction suppression layer contains lithium niobate, lithium silicate (Li4SiO4, Li2SiO3), lithium phosphate, lithium borate, lithium metaphosphate, lithium metaborate, lithium sulfate, lithium tungstate, lithium molybdate, lithium zirconate, lithium aluminate, lithium metatitanate, lithium-titanium oxide and/or their complex oxide. The positive-electrode active-material particles contain lithium cobaltate, lithium nickelate, lithium manganate, lithium-cobalt-nickel-manganese complex oxide, different element-substituted lithium-manganese spinel (Li1+xMn2-x-yMyO4), lithium-titanium complex oxide (LixTiOy), lithium-metal (M') phosphate (LiM'PO4), vanadium pentoxide and/or molybdenum oxide, carbon material containing graphite and hard carbon, and/or active-material substance comprising titanium sulfide, lithium-cobalt nitride, lithium-silicon complex oxide (LixSiyOz), lithium, lithium-metal (M") alloy, magnesium-metal (M1) alloy or metal (N')y-antimony alloy and their derivative, where M is aluminum, magnesium, cobalt, iron, nickel or zinc, M' is iron, manganese, cobalt or nickel, M" is tin, silicon, aluminum, germanium, antimony or phosphorus, M1 is tin, germanium or antimony, N is indium, copper or manganese, and x, y and z are not defined.