SECONDARY BATTERY, METHOD FOR MANUFACTURING SECONDARY BATTERY, ELECTRONIC DEVICE, AND ELECTRIC TOOL

A secondary battery including an electrode wound body having a structure in which a band-shaped positive electrode and a band-shaped negative electrode are stacked and wound with a separator interposed therebetween, an electrolyte solution, a battery can that accommodates the electrode wound body and the electrolyte solution, a battery lid that closes an open end portion of the battery can, and a safety valve mechanism provided between the battery lid and the electrode wound body, wherein the safety valve mechanism includes at least a safety cover, an outer peripheral portion of the battery lid and an outer peripheral portion of the safety cover are joined, and an area of a region where the outer peripheral portion of the battery lid and the outer peripheral portion of the safety cover are joined is 18.1% or more and 25.0% or less of a sectional area of the battery in a radial direction.