All-solid-state secondary battery with solid electrolyte layer containing particulate precipitate of an olivine-type crystal structure

An all-solid-state secondary battery, comprising:

• a solid electrolyte layer;
• a positive electrode layer including a positive electrode active material layer and a first current collector layer;
• a negative electrode layer including a second current collector layer, the positive electrode layer and the negative electrode layer sandwiching the solid electrolyte layer;
• and
• external electrodes connected respectively to the first current collector layer and the second current collector layer,
• wherein the positive electrode active material layer is formed of an olivine-type active material that is LiMPO4, where M is a transition metal,
• wherein the solid electrolyte layer is formed of a phosphate having a NASICON-type structure, and
• wherein the solid electrolyte layer contains particulate precipitate having an olivine-type crystal structure that that is LiMPO4, where M is said transition metal, and an amount of said transition metal M in the solid electrolyte layer being within a range of 0.05 moles and 0.40 moles for each mole of said phosphate having the NASICON-type structure in the solid electrolyte layer.