Cylindrical secondary battery
A cylindrical secondary battery includes: a cylindrical can having a circular bottom portion, a side portion extending from the bottom portion, a beading part concavely formed inwardly at one end of the side portion, and a crimping part formed by bending a distal end of the side portion; an electrode assembly in the can; and a cap assembly sealing the can. The cap assembly includes a gasket for insulation from the can, and an upper portion of the gasket in a direction away from the electrode assembly has a smaller thickness than a lower portion of the gasket.
1 . A cylindrical secondary battery comprising:
a cylindrical can having a circular bottom portion, a side portion extending from the bottom portion, a beading part concavely formed inwardly at one end of the side portion, and a crimping part formed by bending a distal end of the side portion;
an electrode assembly in the can; and
a cap assembly sealing the can, the cap assembly comprising:
a gasket for insulation from the can, an upper portion of the gasket in a direction away from the electrode assembly having a smaller thickness than a lower portion of the gasket;
a cap-up between the crimping part and the beading part; and
a safety vent below the cap-up,
wherein the gasket has an inclined surface that is chamfered on an inner circumferential surface thereof, the inclined surface beginning at an edge of the cap-up, and
wherein a lower surface of an edge of the safety vent is in contact with an upper surface of the cap-up.
2 . The cylindrical secondary battery of claim 1 , wherein the thickness of the upper portion of the gasket decreases toward its end portion.
3 . The cylindrical secondary battery of claim 2 , wherein the gasket has a ring-shaped body, a connection portion extending from the body, and an extension portion extending downwardly from the connection portion, and
wherein a thickness of the body decreases toward its end portion.
4 . The cylindrical secondary battery of claim 3 , wherein the cap assembly further comprises
a cap-down below the safety vent and electrically connected to the electrode assembly, and
wherein the gasket insulates the safety vent and the cap-up from the can.
5 . The cylindrical secondary battery of claim 4 ,
wherein the gasket is bent to surround the edge of the safety vent.
6 . The cylindrical secondary battery of claim 5 , wherein the inclined surface of the gasket is in contact with an upper surface of the edge of the safety vent.
7 . The cylindrical secondary battery of claim 6 , wherein the safety vent is bent to extend over the upper surface of the cap-up, and
wherein a bending position at where the safety vent is bent is at where the inclined surface of the gasket begins.