ACTIVE MATERIAL, ELECTRODE, SECONDARY BATTERY, BATTERY PACK, AND VEHICLE

According to one approach, an active material is provided. The active material includes a first niobium titanium composite oxide expressed by a general formula (I), and a second niobium titanium composite oxide expressed by a general formula (II) and having a rutile-type crystal structure. The first niobium titanium composite oxide belongs to a crystal structure of a space group C2/m, and has a difference Δp between a maximum value and a minimum value of Nb occupancy in a 4i site, the difference Δp being 0.50 ≤ Δp ≤ 0.80, KNbMTiO ... (I) TiNbO ... (II) .