METHOD FOR PRODUCING SECONDARY BATTERY

A secondary battery production method is provided, with which deformation of a current collector is reduced. The method produces a secondary battery including: an electrode assembly having positive and negative electrode plates; and a positive electrode current collector. The positive electrode plate includes a positive electrode core and a positive electrode active material layer, and the electrode assembly includes a positive electrode core-stacked portion. The method includes: an electrode assembly production step of producing the electrode assembly; and an ultrasonic bonding step of ultrasonically bonding the positive electrode current collector to the positive electrode core-stacked portion. The positive electrode current collector has a thin-walled portion. In the ultrasonic bonding step, the thin-walled portion and the positive electrode core-stacked portion are sandwiched between a horn and an anvil, and the thin-walled portion and the positive electrode core-stacked portion are ultrasonically bonded together.