NEGATIVE-ELECTRODE ACTIVE MATERIAL FOR SODIUM-ION SECONDARY BATTERY, METHOD FOR MANUFACTURING SAID NEGATIVE-ELECTRODE ACTIVE MATERIAL, AND SODIUM-ION SECONDARY BATTERY

摘要

A negative-electrode active material for a sodium-ion secondary battery contains a porous carbon material which has a plurality of open pores that extend through to the surface, a plurality of closed pores that do not extend through to the surface, and a solid portion made of carbon material. The distance between (002) planes of carbon in at least a part of the solid portion is 0.36 nm or more. The plurality of closed pores account for a volume ratio of not less than 30% and not more than 90% with respect to a total volume of the plurality of open pores, the plurality of closed pores, and the solid portion.