| 摘要 |
PROBLEM TO BE SOLVED: To provide a square secondary battery capable of enhancing reliability of welding in an electrode external terminal when a battery pack is configured by, for example, jointing a bus bar to the electrode external terminal and connecting a plurality of secondary batteries via the bus bar.SOLUTION: On the surface of a negative electrode external terminal 151, metal powder is accumulated which is made of a material different from a formation material of this negative electrode external terminal 151 and excellent in weldability with the formation material of a positive electrode external terminal 141, and a connection layer 151a is formed by combining the metal powder and the negative electrode external terminal 151 in metallic bond. The surface processing treatment for reducing surface roughness is applied onto the surface of the connection layer 151a. |
