Secondary battery

Abstract

A positive electrode terminal is inserted into a current-collector through hole formed in a positive electrode current collector and riveted in a spot-faced hole formed in the positive electrode current collector. A protrusion is formed on a bottom surface of the spot-faced hole so as to extend around the current-collector through hole, and a riveted portion of the positive electrode terminal covers the protrusion. The riveted portion of the positive electrode terminal is weld-connected to an edge of the spot-faced hole.

What is claimed is: 
     
         1 . A secondary battery comprising:
 an electrode body that includes a positive electrode plate and a negative electrode plate;   an exterior body that has an opening and accommodates the electrode body;   a sealing plate that has a terminal mounting hole and seals the opening;   a current collector that is electrically connected to the positive electrode plate or the negative electrode plate; and   a terminal that is connected to the current collector and inserted in the terminal mounting hole,   wherein the current collector has a current-collector through hole,   wherein a spot-faced hole is formed around the current-collector through hole,   wherein the spot-faced hole has a bottom surface and a side surface, the side surface connects to an outer periphery of the bottom surface,   wherein the terminal is inserted in the current-collector through hole and has a riveted portion which is bent outward from the current-collector through hole in a radial direction of the current-collector through hole,   wherein a protrusion is formed on the bottom surface in such a manner as to extend around the current-collector through hole, the protrusion being located between the current-collector through hole and the side surface in the radial direction of the current-collector through hole,   wherein a gap is formed between the protrusion and the side surface,   wherein the riveted portion of the terminal covers the protrusion,   wherein a portion of the riveted portion is located nearer to the side surface than to a top of the protrusion in the radial direction of the current-collector through hole,   wherein an end of the riveted portion of the terminal is in contact with the side surface,   wherein the riveted portion of the terminal is weld-connected to the side surface of the spot-faced hole, and   wherein in a thickness direction of the sealing plate, a dimension of the side surface is larger than a dimension between the bottom surface and a distal end of the protrusion.   
     
     
         2 . The secondary battery according to  claim 1 ,
 wherein a surface of the protrusion has a curved surface portion.   
     
     
         3 . The secondary battery according to  claim 1 ,
 wherein a height of the protrusion is 0.1 times to 0.5 times a depth of the spot-faced hole.   
     
     
         4 . The secondary battery according to  claim 1 ,
 wherein a corner at an edge of the current-collector through hole has a radius of curvature of 0.05 mm or smaller.   
     
     
         5 . The secondary battery according to  claim 1 ,
 wherein the riveted portion overlaps the protrusion when viewed in a direction in which the terminal is inserted in the current-collector through hole.   
     
     
         6 . The secondary battery according to  claim 1 , wherein the protrusion has a ring-like shape.