SECONDARY BATTERY, ELECTRONIC DEVICE, AND ELECTRIC TOOL

A secondary battery includes: an electrode wound body having a structure in which a strip-shaped negative electrode and a strip-shaped positive electrode opposing each other are laminated and wound with a separator interposed therebetween; a battery can accommodating the electrode wound body; and a battery lid provided over a cavity of the battery can, wherein the positive electrode has a positive electrode end that is located toward the battery lid, the battery can includes: a thick portion that is located toward the battery lid; a thin portion that is located toward a can bottom and has a thickness smaller than a thickness of the thick portion; and a thickness varying portion between the thick portion and the thin portion, and in a sectional view, the thick portion is disposed so as to overlap the positive electrode end.