SECONDARY BATTERY, BATTERY PACK, ELECTRIC VEHICLE, ELECTRIC POWER STORAGE SYSTEM, ELECTRIC POWER TOOL, AND ELECTRONIC APPARATUS

A secondary battery includes a battery element including a positive electrode, a negative electrode, and an electrolytic solution, a housing member having an open end and configured to accommodate the battery element, and a safety valve mechanism attached to the housing member and configured to close the open end. The safety valve mechanism includes a closing member and a coupling member disposed between the battery element and the closing member. The coupling member is electrically coupled to both of a wound electrode body and the closing member, and has a coupling portion physically coupled to the closing member, and a groove is provided in at least part of a peripheral region of the coupling portion.