SODIUM ION SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide means for improving charge and discharge cycle characteristics of a sodium ion secondary battery.SOLUTION: A sodium ion secondary battery comprises: an electrode group including positive and negative electrodes; an electrolyte impregnated into the electrode group; a case having a container having an opening for inserting the electrode group, and an opening-seal plate for closing up the opening; and at least one insulating member for preventing a short circuit. The electrolyte includes a molten salt. The molten salt includes a cation and an anion. The cation includes a sodium ion and an organic cation. The at least one insulating member does not include a fluorine atom.