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

A method of producing a negative electrode active material containing a negative electrode active material particle including a silicon compound particle, comprising the steps of:

• preparing silicon compound particles each containing a silicon compound (SiOx:
• 0.5≤x≤1.6);
• selecting, from the silicon compound particles, a silicon compound particle which has three or more peaks in a chemical shift value ranging from −40 ppm to −120 ppm but has no peak in a chemical shift value within a range of −65±3 ppm in a spectrum obtained by 29Si-MAS-NMR;
• using the selected silicon compound particle to prepare a negative electrode active material particle;
• and
• using the prepared negative electrode active material particle to produce a negative electrode active material.