SECONDARY BATTERY

An embodiment of the present disclosure provides a secondary battery, including: a case including an opening; an electrode assembly disposed within the case, the electrode assembly including a main body and two tabs, the two tabs respectively extending outwards from both sides of the main body in an axial direction of the main body, the two tabs being both disposed facing the case; and a cap assembly including a cap plate, a lower insulating member and an explosion-proof valve, the cap plate sealing the opening, the explosion-proof valve being disposed on the cap plate, the lower insulating member being disposed on a side of the cap plate close to the electrode assembly, the lower insulating member including an inner side surface facing the main body, an outer side surface facing the cap plate, and a concave portion recessed from the inner side surface toward the outer side surface, the concave portion being in position corresponding to the explosion-proof valve, and the concave portion being used to buffer expansion and deformation of the main body. The secondary battery can buffer the expansion of the electrode assembly by the lower insulating member, resulting in the lower insulating member being not prone to deform to squeeze the explosion-proof valve, ensuring the preset bursting pressure of the explosion-proof valve being maintained in a normal state, and improving safety of the secondary battery in use. ( Fig. 1 )