SOLID ELECTROLYTE WITH LOW-SYMMETRY GARNET-RELATED STRUCTURE AND LITHIUM-ION SECONDARY BATTERY

摘要

A solid electrolyte material having high ion conductivity and a all-solid-state lithium-ion secondary battery using this solid electrolyte material are provided. The solid electrolyte material has a garnet-related structure crystal represented by the chemical composition Li_7−x−yLa₃Zr_2−x−yTa_xNb_yO₁₂ (0.05≤x+y≤0.2, x≥0, y≥0), which belongs to an orthorhombic system and a space group belonging to Ibca. The solid electrolyte material has lithium-ion conductivity at 25° C. of at least 1.0×10⁻⁴ S/cm. Also, in this solid electrolyte material, the lattice constants are 1.29 nm≤a≤1.32 nm, 1.26 nm≤b≤1.29 nm, and 1.29 nm≤c≤1.32 nm, and three 16f sites and one 8d site in the crystal structure are occupied by lithium-ions. The all-solid-state lithium-ion secondary battery has a positive electrode, a negative electrode, and a solid electrolyte, the solid electrolyte comprising this solid electrolyte material.