| abstract |
According to one embodiment, an active material including a composite oxide is provided. The composite oxide has a monoclinic crystal structure and is represented by the general formula Li w M1 2−x Ti 8−y M2 z O 17+δ , wherein: M1 is at least one selected from the group consisting of Cs, K, and Na; M2 is at least one selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Fe, Co, Mn, and Al; n 0≤w≤10; 0<x<2; 0<y<8; 0<z<8;n nand −0.5≤δ≤0.5. |