Negative electrode active material, negative electrode, and battery

A negative electrode active material comprising an alloy particle, the alloy particle containing:

• an alloy component containing, in atomic composition percentage excluding oxygen, Sn:
• 13.0 to 40.0 at % and Si:
• 6.0 to 40.0 at %, with the balance being Cu and impurities, and
• oxygen in an amount in a range of 0.50 to 3.00 mass %;
• wherein:
• the alloy particle contains:
• one type or two types of phase selected from a group consisting of a phase having a D03 structure in Strukturbericht notation in which an Si content is in a range of 0 to 5.0 at % and a δ phase in which an Si content is in a range of 0 to 5.0 at %,
• one type or two types of phase selected from a group consisting of an ε phase in which an Si content is in a range of 0 to 5.0 at % and an η′ phase in which an Si content is in a range of 0 to 5.0 at %, and
• an SiOx phase (x=0.50 to 1.70);
• and
• the alloy particle has, in an X-ray diffraction profile, a peak having a largest integrated diffraction intensity in a range of 42.0 to 44.0 degrees of a diffraction angle 2θ, with a half-width of the peak being in a range of 0.15 to 2.50 degrees.