NEGATIVE ELECTRODE ACTIVE SUBSTANCE MATERIAL.

摘要

Provided is a negative electrode active substance material that can improve the capacity per volume and charge-discharge cycle characteristics of a nonaqueous electrolyte secondary cell such as a lithium ion secondary cell. The negative electrode active substance material according to the present embodiment contains an alloy phase. The alloy phase goes through thermoelastic diffusionless transformation when metal ions are released or when metal ions are occluded. The negative electrode active substance material of the present embodiment is used in nonaqueous electrolyte secondary cells. Thermoleastic diffusionless transformation is defined as so-called thermoelastic martensitic transformation.