Negative electrode active material and battery

A battery comprising:

• a negative electrode including a negative electrode active material;
• a positive electrode;
• and
• an electrolyte, wherein:
• the negative electrode active material includes:
• a carbon material including boron;
• and
• a silicon material including at least one selected from silicon and silicon oxide;
• a peak of a B1s spectrum of the carbon material occurs at a binding energy of 187.0 eV or more and 188.5 eV or less, the B1s spectrum being measured by X-ray photoelectron spectroscopy,
• the silicon material do not include boron,
• the silicon oxide is SiOx, where 0.1≤x≤1.2,
• a ratio of an amount of the silicon oxide included in the silicon material to a total amount of the negative electrode active material is 0.5% by weight or more and 50% by weight or less, and
• a ratio of the area of the peak of the B1s spectrum of the carbon material which occurs at a binding energy of 187.0 eV or more and 188.5 eV or less to the total area of peaks of the B1s spectrum which occur at a binding energy of 184.0 eV or more and 196.5 eV or less is 50% or more.