PURPOSE: To improve the strength of a solid electrolyte by depositing an amorphous material containing SiO2 on a ceramic crystal grain boundary, and giving Na ion conductivity to the amorphous material.
CONSTITUTION: A solid electrolyte for a secondary battery is made of ceramic C mainly constituted of either one of β-alumina, β"-alumina and a mixture of β-alumina and β"-alumina. The solid electrolyte for the secondary battery is deposited with an amorphous material containing SiO2 on the crystal grain boundary of ceramic C, and this amorphous material has Na ion conductivity. The ion conduction resistance of ceramic C is not increased, Na ions pass the amorphous material and are moved to adjacent crystal grains even if Na ion conduction faces of crystal grain boundaries differ, thus no Na is deposited on the grain boundary. The strength of the solid electrolyte is improved.
HIDA HIROSHI
NISHIMURA SHIGEOKI
