Negative electrode active material for non-aqueous electrolyte secondary battery, non-aqueous electrolyte secondary battery, and method for producing negative electrode material for non-aqueous electrolyte secondary battery

A method for producing a negative electrode material for a non-aqueous electrolyte secondary battery, the negative electrode material comprising negative electrode active material particles which comprise a silicon compound particle, the method comprising:

• producing a silicon compound particle which comprises a silicon compound comprising oxygen;
• modifying the silicon compound particle by inserting Li into the silicon compound particle;
• and
• adhering a phosphate salt that is at least one of an aluminum phosphate salt and an ammonium phosphate salt on a surface of the silicon compound particle after modification, thereby producing the negative electrode material for the non-aqueous aqueous electrolyte secondary battery, wherein a content of the phosphate salt is 0.1% by mass or more and 7% by mass or less relative to the silicon compound particle.