Patent ID: 8906545

Claim:
A prismatic secondary battery comprising: a prismatic outer casing having a mouth; an electrode assembly housed inside the prismatic outer casing and having a positive electrode plate and a negative electrode plate; a positive electrode collector electrically connected to the positive electrode plate; a negative electrode collector electrically connected to the negative electrode plate; a sealing body sealing the mouth of the outer casing; a positive electrode external terminal containing an aluminum-based metal and a negative electrode external terminal containing a copper-based metal, each inserted into a through-hole provided in the sealing body while being electrically insulated from the sealing body with an insulating member interposed therebetween; and a positive electrode terminal plate and a negative electrode terminal plate arranged on the positive electrode external terminal and the negative electrode external terminal, respectively, the positive electrode collector and the negative electrode collector being electrically connected to the positive electrode terminal plate and the negative electrode terminal plate, respectively, the positive electrode terminal plate and the negative electrode terminal plate each having a through-hole having a tapered portion formed on the upper end side thereof, the positive electrode external terminal and the negative electrode external terminal each having an upper end portion inserted into the through-holes of the positive electrode terminal plate and the negative electrode terminal plate, respectively, from the lower end side thereof, the upper end portions of the positive electrode external terminal and the negative electrode external terminal being crimped on the upper end side to be mechanically and electrically connected to the positive electrode terminal plate and the negative electrode terminal plate, respectively, the crimped portions of the positive electrode external terminal and the negative electrode external terminal each having a plurality of weld spots formed adjacent to the positive electrode terminal plate and the negative electrode terminal plate, respectively, by application of high energy beams, and the contact area between the positive electrode terminal plate and the crimped portion of the positive electrode external terminal being smaller than the contact area between the negative electrode terminal plate and the crimped portion of the negative electrode external terminal, and the volume of the crimped portion of the positive electrode external terminal being larger than that of the crimped portion of the negative electrode external terminal.