A battery cell, comprising: a housing with an opening; an electrode assembly for being accommodated in the housing, wherein the electrode assembly comprises a main body portion and a tab; and an end cover assembly, comprising an end cover and an electrode terminal, the end cover is configured to cover the opening, the electrode terminal is mounted on the end cover, and the electrode terminal is configured to be electrically connected to the tab, wherein the end cover comprises a first body and a first protruding portion, the first body has a first inner surface and a first outer surface arranged opposite to each other in a thickness direction of the first body, the first protruding portion protrudes from the first outer surface in a direction departing from the main body portion, a first recessed portion, which is recessed from the first inner surface in the direction departing from the main body portion, is formed at a position corresponding to the first protruding portion on the first body, and the first recessed portion is configured to accommodate at least a part of the tab; and wherein the end cover assembly further comprises a first insulating piece; and the first insulating piece is disposed on a side of the end cover facing the main body portion, and the first insulating piece is configured to isolate the end cover from the electrode assembly; and wherein the first insulating piece comprises a second body and a second protruding portion, the second body has a second inner surface and a second outer surface arranged opposite to each other in the thickness direction, the second outer surface faces the first inner surface, the second protruding portion protrudes from the second outer surface in the direction departing from the main body portion, and a second recessed portion recessed from the second inner surface in the direction departing from the main body portion is formed at a position corresponding to the second protruding portion on the second body; and the first recessed portion is configured to accommodate the second protruding portion, and the second recessed portion is configured to accommodate at least a part of the tab. a housing with an opening; an electrode assembly for being accommodated in the housing, wherein the electrode assembly comprises a main body portion and a tab; and an end cover assembly, comprising an end cover and an electrode terminal, the end cover is configured to cover the opening, the electrode terminal is mounted on the end cover, and the electrode terminal is configured to be electrically connected to the tab, wherein the end cover comprises a first body and a first protruding portion, the first body has a first inner surface and a first outer surface arranged opposite to each other in a thickness direction of the first body, the first protruding portion protrudes from the first outer surface in a direction departing from the main body portion, a first recessed portion, which is recessed from the first inner surface in the direction departing from the main body portion, is formed at a position corresponding to the first protruding portion on the first body, and the first recessed portion is configured to accommodate at least a part of the tab; and wherein the end cover assembly further comprises a first insulating piece; and the first insulating piece is disposed on a side of the end cover facing the main body portion, and the first insulating piece is configured to isolate the end cover from the electrode assembly; and wherein the first insulating piece comprises a second body and a second protruding portion, the second body has a second inner surface and a second outer surface arranged opposite to each other in the thickness direction, the second outer surface faces the first inner surface, the second protruding portion protrudes from the second outer surface in the direction departing from the main body portion, and a second recessed portion recessed from the second inner surface in the direction departing from the main body portion is formed at a position corresponding to the second protruding portion on the second body; and the first recessed portion is configured to accommodate the second protruding portion, and the second recessed portion is configured to accommodate at least a part of the tab.