Cap assembly for secondary battery, secondary battery and battery module

Abstract

The present disclosure provides a cap assembly for a secondary battery, a secondary battery and a battery module. The cap assembly for the secondary battery includes a cap plate, a first electrode terminal, and a sealing member, wherein: the cap plate has an electrode lead-out hole; the first electrode terminal includes a first terminal board and a second terminal board connected with the first terminal board, wherein the first terminal board is located at a side of the second terminal board away from the cap plate, the second terminal board covers the electrode lead-out hole, and the material of the first terminal board and the material of the second terminal board have different base metals; the sealing member surrounds the electrode lead-out hole and is disposed between the cap plate and the first electrode terminal to seal the electrode lead-out hole.

What is claimed is: 
     
         1 . A cap assembly for a secondary battery, comprising a cap plate, a first electrode terminal, a sealing member, a fixing member and a connecting member, wherein:
 the cap plate has an electrode lead-out hole;   the first electrode terminal comprises a first terminal board and a second terminal board connected with the first terminal board, wherein the first terminal board is located at a side of the second terminal board away from the cap plate, the second terminal board covers the electrode lead-out hole, and the material of the first terminal board and the material of the second terminal board have different base metals;   the sealing member surrounds the electrode lead-out hole and is disposed between the cap plate and the first electrode terminal to seal the electrode lead-out hole; and   the fixing member is fixed to the cap plate through the connecting member, and an outer peripheral surface of the first electrode terminal is at least partially surrounded by the fixing member to fix the first electrode terminal to the fixing member.   
     
     
         2 . The cap assembly of  claim 1 , wherein the sealing member is in close contact with the cap plate and the second terminal board. 
     
     
         3 . The cap assembly of  claim 1 , wherein the first terminal board and the second terminal board form a composite board strip. 
     
     
         4 . The cap assembly of  claim 1 , wherein the second terminal board further comprises an extension portion extending into the electrode lead-out hole. 
     
     
         5 . The cap assembly of  claim 1 , wherein the first terminal board and the second terminal board are joined together by a cold rolling method, a hot rolling method, an explosion compound method, or an explosion rolling method. 
     
     
         6 . The cap assembly of  claim 1 , wherein one of the first electrode terminal and the fixing member has a convex portion, and the other has a concave portion that accommodates the convex portion, and the convex portion is fitted with the concave portion. 
     
     
         7 . The cap assembly of  claim 6 , wherein the convex portion is provided on the outer peripheral surface of the first electrode terminal, the concave portion is provided on an inner wall surface of the fixing member corresponding to the convex portion, and a surface of the first electrode terminal away from the cap plate protrudes from a surface of the fixing member away from the cap plate. 
     
     
         8 . The cap assembly of  claim 7 , wherein the convex portion is provided on an outer peripheral surface of the first terminal board. 
     
     
         9 . The cap assembly of  claim 1 , wherein the fixing member is a hard plastic member, a portion of the fixing member is located between the cap plate and the first electrode terminal. 
     
     
         10 . The cap assembly of  claim 1 , wherein the connecting member comprises a nail body and a limiting portion which are connected with each other, and wherein an outer peripheral surface of the limiting portion protrudes from an outer peripheral surface of the nail body, an end of the nail body away from the limiting portion is fixed on the cap plate, and the limiting portion is engaged with the fixing member. 
     
     
         11 . The cap assembly of  claim 1 , wherein the connecting member comprises a first connecting plate, and wherein a portion of the first connecting plate is embedded into the fixing member and engaged with the fixing member, and another portion of the first connecting plate is welded with the cap plate. 
     
     
         12 . The cap assembly of  claim 1 , further comprising a second electrode terminal, a deformable sheet and a conductive sheet, wherein the second electrode terminal is electrically connected with the cap plate, the first electrode terminal is insulated from the cap plate, the deformable sheet is attached to cap plate, the conductive sheet is electrically connected with the first electrode terminal,
 wherein when a pressure within the secondary battery exceeds a predetermined pressure value, the deformable sheet deforms and is electrically connected with the conductive sheet.   
     
     
         13 . The cap assembly of  claim 12 , wherein the conductive sheet and the first electrode terminal are located on the same side of the cap plate, a surface of the conductive sheet away from the cap plate protrudes from a surface of the first electrode terminal away from the cap plate. 
     
     
         14 . The cap assembly of  claim 12 , wherein the material of the first terminal board and the material of the conductive sheet have a same base metal. 
     
     
         15 . A secondary battery, comprising:
 a shell having an opening;   an electrode assembly accommodated in the shell; and   the cap assembly of  claim 1 , wherein the cap assembly covers the opening of the shell to enclose the electrode assembly in the shell   
     
     
         16 . A battery module, comprising:
 a busbar; and   the secondary battery of  claim 15 , wherein the busbar is welded to the first terminal board.   
     
     
         17 . The battery module of  claim 16 , wherein the material of the busbar and the material of the first terminal hoard have a same base metal.