An energy storage device, comprising: a connector; a tab connected to the connector; and a welding protection sheet abutting against a surface of the tab away from the connector, wherein the welding protection sheet comprises a body, a first bent connection portion, and a first extending portion, wherein: each of the body and the first extending portion extends in a first direction; the first bent connection portion is connected between the first extending portion and the body; and the first extending portion is foldable relative to the body to face towards the body; each of two opposite ends of an end portion of the first extending portion away from the first bent connection portion in the first direction has a first notch, wherein the first notch has a width in a second direction less than a width of the first extending portion in the second direction, wherein the second direction is perpendicular to the first direction; and two first corners are formed at connections between two end portions of the first extending portion in the first direction and the end portion of the first extending portion away from the first bent connection portion, wherein a distance between the two first corners in the first direction is less than a length of the body in the first direction. a connector; a tab connected to the connector; and a welding protection sheet abutting against a surface of the tab away from the connector, wherein the welding protection sheet comprises a body, a first bent connection portion, and a first extending portion, wherein: each of the body and the first extending portion extends in a first direction; the first bent connection portion is connected between the first extending portion and the body; and the first extending portion is foldable relative to the body to face towards the body; each of two opposite ends of an end portion of the first extending portion away from the first bent connection portion in the first direction has a first notch, wherein the first notch has a width in a second direction less than a width of the first extending portion in the second direction, wherein the second direction is perpendicular to the first direction; and two first corners are formed at connections between two end portions of the first extending portion in the first direction and the end portion of the first extending portion away from the first bent connection portion, wherein a distance between the two first corners in the first direction is less than a length of the body in the first direction. each of the body and the first extending portion extends in a first direction; the first bent connection portion is connected between the first extending portion and the body; and the first extending portion is foldable relative to the body to face towards the body; each of two opposite ends of an end portion of the first extending portion away from the first bent connection portion in the first direction has a first notch, wherein the first notch has a width in a second direction less than a width of the first extending portion in the second direction, wherein the second direction is perpendicular to the first direction; and two first corners are formed at connections between two end portions of the first extending portion in the first direction and the end portion of the first extending portion away from the first bent connection portion, wherein a distance between the two first corners in the first direction is less than a length of the body in the first direction.