Negative electrode active material, mixed negative electrode active material, and method for producing negative electrode active material

A method for producing a negative electrode active material which comprises a negative electrode active material particle comprising a silicon compound particle, the method comprising the steps of:

• making silicon compound particles comprising a silicon compound (SiOx:
• 0.5≤x≤1.6);
• inserting lithium into the silicon compound particles so as to include crystalline Li2Si2O5 in at least part of the silicon compound particles to prepare negative electrode active material particles;
• selecting, from the negative electrode active material particles, such a negative electrode active material particle that, among a peak intensity A derived from Li2SiO3, a peak intensity B derived from Si, a peak intensity C derived from Li2Si2O5, and a peak intensity D derived from SiO2 which are obtained from a 29Si-MAS-NMR spectrum of the negative electrode active material particle, the peak intensity C is the highest intensity, and the peak intensity A and the peak intensity C satisfy a relationship of the following formula 1;
• and
• producing a negative electrode active material by using the selected negative electrode active material particle,
• A<C/3 formula 1.