A secondary battery , comprising: a casing , which includes a receiving hole having an opening; a top cover assembly , which includes a top cover plate connected to the casing to close the opening; an electrode assembly , which is disposed within the receiving hole , the electrode assembly includes two end faces which are opposed to each other in a first direction (Y) perpendicular to an axial direction (X) of the receiving hole and tabs extending from the end faces , the electrode assembly further includes two or more electrode units which are laminated in the axial direction (X), and in a second direction (Z) perpendicular to the axial direction (X) and the first direction (Y), a dimension of the tab is smaller than a dimension of the end face ; and a current collecting member , which is electrically connected to the tab , wherein the electrode unit has two wide faces and two narrow faces connecting the two wide faces , an area of each of the two wide faces is larger than an area of each of the two narrow faces , the two wide faces are disposed to be opposite to each other in the axial direction (X), and the two wide faces and the two narrow faces are alternately disposed; and wherein the current collecting member includes a connecting portion disposed between the end face and the casing , the connecting portion has a first sheet extending along the axial direction (X) and a current collecting piece through which the tab is electrically connected to the first sheet , the current collecting piece and the tab are folded with respect to the first direction (Y) such that the tab is connected to a surface of the current collecting piece facing away from the end face . a casing , which includes a receiving hole having an opening; a top cover assembly , which includes a top cover plate connected to the casing to close the opening; an electrode assembly , which is disposed within the receiving hole , the electrode assembly includes two end faces which are opposed to each other in a first direction (Y) perpendicular to an axial direction (X) of the receiving hole and tabs extending from the end faces , the electrode assembly further includes two or more electrode units which are laminated in the axial direction (X), and in a second direction (Z) perpendicular to the axial direction (X) and the first direction (Y), a dimension of the tab is smaller than a dimension of the end face ; and a current collecting member , which is electrically connected to the tab , wherein the electrode unit has two wide faces and two narrow faces connecting the two wide faces , an area of each of the two wide faces is larger than an area of each of the two narrow faces , the two wide faces are disposed to be opposite to each other in the axial direction (X), and the two wide faces and the two narrow faces are alternately disposed; and wherein the current collecting member includes a connecting portion disposed between the end face and the casing , the connecting portion has a first sheet extending along the axial direction (X) and a current collecting piece through which the tab is electrically connected to the first sheet , the current collecting piece and the tab are folded with respect to the first direction (Y) such that the tab is connected to a surface of the current collecting piece facing away from the end face . <EOS>