Secondary battery, method for manufacturing secondary battery, electronic device, and electric tool

A method for manufacturing a secondary battery, the secondary battery comprising:

• providing 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;
• providing an electrolyte solution;
• providing a battery can that accommodates the electrode wound body and the electrolyte solution;
• providing a battery lid that closes an open end portion of the battery can;
• and
• providing 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 by a welding method, 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.