SECONDARY BATTERY, BATTERY PACK, AND VEHICLE

According to one embodiment, provided is a secondary battery including a positive electrode, a negative electrode, and an electrolyte. The negative electrode includes a niobium-titanium composite oxide having fluorine atoms on at least part of a surface the niobium-titanium composite oxide. An abundance ratio Aof fluorine atoms, an abundance ratio Aof titanium atoms, and an abundance ratio Aof niobium atoms on a surface of the negative electrode according to X-ray photoelectron spectroscopy satisfy a relationship of 3.5≤A/(A+A)≤50.