A battery cell, comprising: an electrode assembly; a cylindrical case for accommodating the electrode assembly, wherein the case has an opening and a first position-limiting portion, wherein the first position-limiting portion is a flanging structure formed on the surface side of the end cover facing away from the electrode assembly by partially folding the case towards the end cover; an end cover for covering the opening, wherein in the thickness direction of the end cover, the end cover is located on one side of the first position-limiting portion facing the electrode assembly, and the first position-limiting portion is used for restricting the movement of the end cover in a direction away from the electrode assembly; and a sealing member for sealing the end cover and the first position-limiting portion, so that the end cover and the first position-limiting portion are in sealed connection; wherein the end cover comprises a cover body and a protrusion protruding from the surface of the cover body facing away from the electrode assembly in the thickness direction of the end cover, and at least part of the sealing member is clamped between the protrusion and the first position-limiting portion, the protrusion being annularly distributed around the circumference of the end cover, and the cross-section of the protrusion is semicircular, wherein the first position-limiting portion comprises a first portion and a second portion which are connected, the first portion covers the protrusion, and the second portion extends a first predetermined distance from an end of the first portion near the center of the end cover towards the center of the end cover, wherein in the unfolded state of the first position-limiting portion, the second portion comprises a plurality of notches spaced around a central axis of the case, and each notch extends to an end of the second portion away from the first portion;, the battery cell being characterised in that the notch comprises two tangential edges intersecting at a vertex and forming a predetermined angle (α), and after the first position-limiting portion is folded towards the end cover, the two tangential edges leading from the vertex are butted, so that the second portion forms a complete annular structure. an electrode assembly; a cylindrical case for accommodating the electrode assembly, wherein the case has an opening and a first position-limiting portion, wherein the first position-limiting portion is a flanging structure formed on the surface side of the end cover facing away from the electrode assembly by partially folding the case towards the end cover; an end cover for covering the opening, wherein in the thickness direction of the end cover, the end cover is located on one side of the first position-limiting portion facing the electrode assembly, and the first position-limiting portion is used for restricting the movement of the end cover in a direction away from the electrode assembly; and a sealing member for sealing the end cover and the first position-limiting portion, so that the end cover and the first position-limiting portion are in sealed connection; wherein the end cover comprises a cover body and a protrusion protruding from the surface of the cover body facing away from the electrode assembly in the thickness direction of the end cover, and at least part of the sealing member is clamped between the protrusion and the first position-limiting portion, the protrusion being annularly distributed around the circumference of the end cover, and the cross-section of the protrusion is semicircular, wherein the first position-limiting portion comprises a first portion and a second portion which are connected, the first portion covers the protrusion, and the second portion extends a first predetermined distance from an end of the first portion near the center of the end cover towards the center of the end cover, wherein in the unfolded state of the first position-limiting portion, the second portion comprises a plurality of notches spaced around a central axis of the case, and each notch extends to an end of the second portion away from the first portion;, the battery cell being characterised in that the notch comprises two tangential edges intersecting at a vertex and forming a predetermined angle (α), and after the first position-limiting portion is folded towards the end cover, the two tangential edges leading from the vertex are butted, so that the second portion forms a complete annular structure.