ELECTRODE, SECONDARY BATTERY, BATTERY PACK, AND VEHICLE

According to one embodiment, an electrode includes a current collector and an active material-containing layer. The active material-containing layer contains a titanium-niobium composite oxide. A cross-section of the active material-containing layer includes a first cross-section from the current collector to length 0.5t with respect to a thickness t of the active material-containing layer, and a second cross-section from length 0.5t to length t from the current collector. An area ratio S1 occupied by the titanium-niobium composite oxide within the first cross-section, and an area ratio S2 occupied by the titanium-niobium composite oxide within the second cross-section satisfy 0.8