Secondary battery having cap assembly

Abstract

A secondary battery having a cap assembly, including an electrode assembly; a case in which the electrode assembly is located; a cap assembly having a cap plate coupled to and hermetically sealing the case. A terminal member has a head with a stepped protrusion penetrating the cap plate and insulated from the cap plate by an insulating member. The stepped protrusion presses the insulating member in multiple steps. The terminal member is connected to a positive or negative electrode terminal of the electrode assembly.

What is claimed is: 
     
       1. A secondary battery having a cap assembly, comprising:
 an electrode assembly having a negative electrode and a positive electrode; 
 a case in which the electrode assembly is located; and 
 a cap assembly having a cap plate coupled to the case and hermetically sealing the case, a terminal member having a head and a stepped protrusion, penetrating the cap plate, and an insulating member insulating the terminal member from the cap plate, wherein the stepped protrusion presses the insulating member in multiple steps and contacts with the insulating member at a plurality of parallel surfaces, wherein the parallel surfaces are not co-planar, and the terminal member is connected to a terminal of the electrode assembly. 
 
     
     
       2. The secondary battery according to  claim 1 , wherein the head has one of a non-circular and rectangular shape. 
     
     
       3. The secondary battery according to  claim 1 , wherein the stepped protrusion is no wider than the head. 
     
     
       4. A secondary battery having a cap assembly, comprising:
 an electrode assembly having a plurality of negative and positive electrode plates; 
 a rectangular case in which the electrode assembly is located; and 
 a cap assembly having a cap plate, coupled to the case and hermetically sealing the case, a gasket positioned on an outside surface of the cap plate, an insulating plate and a terminal plate positioned on an inside surface of the cap plate, and a terminal member having a head with a stepped protrusion, wherein the stepped protrusion penetrates aligned throughholes in the cap plate, the gasket, and the insulating plate, and the terminal plate member is riveted at the stepped protrusion., so the head presses against the gasket in multiple steps at a plurality of parallel surfaces, wherein the parallel surfaces are not co-planar. 
 
     
     
       5. The secondary battery according to  claim 4 , wherein the head has one of a non-circular and rectangular shape. 
     
     
       6. The secondary battery according to  claim 4  wherein the stepped protrusion is no wider than the head. 
     
     
       7. The secondary battery according to claim 1, wherein the head and a stepped portion of the stepped protrusion contact with the insulating member. 
     
     
       8. The secondary battery according to claim 1, wherein a stepped portion of the stepped protrusion comprises a flat surface. 
     
     
       9. The secondary battery according to claim 1, wherein a portion of the stepped protrusion penetrates the cap plate and the insulating member. 
     
     
       10. The secondary battery according to claim 1, wherein the terminal member is riveted. 
     
     
       11. The secondary battery according to claim 1, where bottom surfaces of the head and the stepped portion contact with the insulating member. 
     
     
       12. The secondary battery according to claim 1, wherein the stepped protrusion has a width smaller than or equal to a smaller width of the head. 
     
     
       13. The secondary battery according to claim 1, wherein a bottom surface of the stepped protrusion is flat. 
     
     
       14. The secondary battery according to claim 1, wherein the extension of the stepped protrusion penetrates the cap plate and the insulating member. 
     
     
       15. The secondary battery according to claim 14, wherein an end of the extension is riveted. 
     
     
       16. The secondary battery according to claim 4, wherein the stepped protrusion has a width smaller than or equal to a smaller width of the head. 
     
     
       17. The secondary battery according to claim 4, wherein the bottom surface of the protrusion is flat. 
     
     
       18. The secondary battery according to claim 4, wherein an extension of the stepped protrusion penetrates aligned through holes in the cap plate, the gasket, and the insulating plate. 
     
     
       19. The secondary battery according to claim 18, wherein an end of the extension is riveted.