SECONDARY BATTERY HAVING CASE WITH RECESSED PORTION AND MANUFACTURING METHOD THEREOF

A secondary battery including a case having a bottom surface, the bottom surface including a recessed portion and a non-recessed portion, the recessed portion being recessed into an interior of the case, and the non-recessed portion being flat, and an upper surface facing the bottom surfaces, the upper surfaces including a cap assembly, and an electrode assembly accommodated in the case.