Abstract: A battery with no roll groove comprising a cap, an outer washer, a casing and a rolled core, wherein the rolled core is accommodated in the casing, and the cap is electrically connected to the rolled core; a top portion of the casing is bent inward and tightly presses the outer washer against the cap, thereby fixing the rolled core in the casing; the casing has no roll groove structure. The outer washer comprises an outer washer top portion, the outer washer top portion being an annular structure, and the cap being exposed through a central round opening; and an outer washer bottom portion, disposed between the cap and the casing.

Abstract: A battery cap and a battery including the battery cap. The battery cap comprises a top cover; an anti-explosion valve plate, the anti-explosion valve plate being arranged below the top cover and electrically connected to the top cover, and an outer periphery dimension of the anti-explosion valve plate being smaller than an outer periphery dimension of the top cover; an orifice plate, the orifice plate being arranged below the anti-explosion valve plate, and the orifice plate and the anti-explosion valve plate being electrically connected at a central position, and being separated at a peripheral position with a gap; and an internal washer, the internal washer being used for sealing the gap between the outer peripheries of the anti-explosion valve plate and the orifice plate. The present invention may effectively seal electrolyte under normal operating conditions, and quickly and effectively relieve pressure in an emergency situation.