A battery cell, a battery, and an electric device are provided. The battery cell includes: a housing having a first wall; a pressure relief mechanism provided on the first wall; an electrode leading-out portion provided on the housing; an electrode assembly provided in the housing and provided with tabs; and an adapter connected to the electrode leading-out portion and the tabs, wherein the adapter is provided with a reinforcing portion, and in the thickness direction of the first wall, the projection of the reinforcing portion on the first wall at least partially covers the pressure relief mechanism.