A battery cell, the battery cell being a cylindrical battery cell, the battery cell comprising: a shell; an electrode assembly, configured to be accommodated in the shell; an electrode terminal; and an end cover, configured to seal an opening at one end of the shell, the end cover being sleeved outside the electrode terminal, and part of the electrode terminal being protruded out of the end cover; a current collector, configured to connect the electrode assembly and the electrode terminal, an insulating piece, extending between the end cover and the current collector, and configured to isolate the end cover from the electrode terminal, wherein the electrode terminal, the end cover and the insulating piece are assembled integrally and form an end cover assembly, the end cover assembly, the current collector and the electrode assembly are arranged sequentially in a thickness direction of the current collector; wherein the current collector and the electrode terminal are connected through a welding portion, and the welding portion is exposed at an external peripheral surface of the current collector and an external peripheral surface of the electrode terminal; and the current collector includes a protrusion, the protrusion is protruded towards the electrode terminal in the thickness direction of the current collector, the protrusion is configured to be connected to the electrode terminal, and an external peripheral surface of the protrusion and the external peripheral surface of the electrode terminal are connected through the welding portion; wherein an external peripheral surface of the current collector is a side surface of the protrusion, an external peripheral surface of the protrusion is the side surface of the protrusion, and the welding portion is exposed at the side surface of the protrusion; the electrode terminal includes a terminal body and a terminal pedestal, and one end of the terminal body and the terminal pedestal are connected or integrally formed; the terminal pedestal is configured to be connected to the current collector; and the terminal body is configured to be connected to the confluence part to lead out the electric energy; a groove is formed on an external peripheral surface of the terminal pedestal, and the protrusion is configured to cooperate with the groove and the protrusion is configured to be inserted into the groove. a shell; an electrode assembly, configured to be accommodated in the shell; an electrode terminal; and an end cover, configured to seal an opening at one end of the shell, the end cover being sleeved outside the electrode terminal, and part of the electrode terminal being protruded out of the end cover; a current collector, configured to connect the electrode assembly and the electrode terminal, an insulating piece, extending between the end cover and the current collector, and configured to isolate the end cover from the electrode terminal, wherein the electrode terminal, the end cover and the insulating piece are assembled integrally and form an end cover assembly, the end cover assembly, the current collector and the electrode assembly are arranged sequentially in a thickness direction of the current collector; wherein the current collector and the electrode terminal are connected through a welding portion, and the welding portion is exposed at an external peripheral surface of the current collector and an external peripheral surface of the electrode terminal; and the current collector includes a protrusion, the protrusion is protruded towards the electrode terminal in the thickness direction of the current collector, the protrusion is configured to be connected to the electrode terminal, and an external peripheral surface of the protrusion and the external peripheral surface of the electrode terminal are connected through the welding portion; wherein an external peripheral surface of the current collector is a side surface of the protrusion, an external peripheral surface of the protrusion is the side surface of the protrusion, and the welding portion is exposed at the side surface of the protrusion; the electrode terminal includes a terminal body and a terminal pedestal, and one end of the terminal body and the terminal pedestal are connected or integrally formed; the terminal pedestal is configured to be connected to the current collector; and the terminal body is configured to be connected to the confluence part to lead out the electric energy; a groove is formed on an external peripheral surface of the terminal pedestal, and the protrusion is configured to cooperate with the groove and the protrusion is configured to be inserted into the groove.