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

According to one approach, provided is an active material including a composite oxide having a monoclinic crystal structure. The composite oxide is represented by a general formula LiNbMWO. Herein, M includes at least one selected from the group consisting of Ta, Ti, Zr, Al, and Fe, and 0 ≤ x ≤ 5, -0.5 ≤ y ≤ 2, 0 ≤ z ≤ 2, and 4 ≤ u ≤ 9.