NEGATIVE ELECTRODE ACTIVE MATERIAL FOR LITHIUM ION SECONDARY BATTERIES, AND LITHIUM ION SECONDARY BATTERY

摘要

Provided is a negative electrode active material which contains a graphite powder and a silicon oxide powder that has an Si phase and an SiO2 phase. With respect to this negative electrode active material, the mass ratio of the silicon oxide powder to the total mass of the silicon oxide powder and the graphite powder is 0.1-0.5, and the silicon oxide powder has a particle diameter D50 of 4 mum or more. Consequently, there can be provided a negative electrode active material which is capable of providing a lithium ion secondary battery that has excellent capacity and cycle characteristics.