Secondary battery and secondary battery manufacturing method

摘要

In a secondary battery, for providing a structure which can enable a welding operation even when a gap is formed between a current collecting plate and a winding assembly, recessed portions 8 are formed in a positive current collecting plate 6. The recessed portions 8 are disposed opposite to the winding assembly 5. A laser beam is irradiated to welding protrusions 9 located between the recessed portions 8 to melt the welding protrusions. Here, since the end surface of a positive electrode foil 1 is uneven in height, the positive electrode foil 1 does not contact the positive current collecting plate 6 necessarily. The welding operation is performed by heating, melting, and dropping the welding protrusions 9 by the use of a YAG laser under the welding condition of a laser power of 900 W and a welding speed 2 m/min.