US Patent 9923186 Rectangular secondary battery

A square secondary battery includes a can housing a power generation element, a lid sealing an opening of the can, an external terminal arranged on the lid, a current collector connected to each of the electrodes of the power generation element, and a connection terminal connecting the current collector and the external terminal by passing through the lid. The external terminal has a flat plate shape arranged along the lid and is made of a clad material in which two flat plate portions made of mutually dissimilar metals are clad-joined on wide-width surfaces and the connection terminal is joined by welding with, of the two flat plate portions of the external terminal, the flat plate portion arranged on a side of the lid.