SODIUM MOLTEN SALT BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a sodium molten salt battery superior in charge and discharge cycle characteristics.SOLUTION: A sodium molten salt battery comprises: a positive electrode including a positive electrode active material capable of electrochemically occluding and releasing sodium ions; a negative electrode including a negative electrode active material capable of electrochemically occluding and releasing sodium ions; and a molten salt electrolyte including a sodium salt and an ionic liquid in which the sodium salt can dissolve. The negative electrode active material includes a carbon hard to graphitize. The ionic liquid is a salt of a first onium cation which causes no Faraday reaction with the carbon hard to graphitize, and a bis(sulfonyl)imide anion. The molten salt electrolyte includes 1000 ppm or less of a second onium cation by mass ratio. The second onium cation is expressed by the general formula (1): RRRRN, where Rto Rrepresent a hydrogen atom or a methyl group independently of one another.