BATTERY COVER PLATE ASSEMBLY, BATTERY CELL, BATTERY AND ELECTRIC DEVICE

The present application provides a battery cover plate assembly, including: a cover plate provided with a filling port; and a sealing pin for sealing the filling port; wherein the sealing pin includes a main body portion and a welding portion, and the welding portion is located at a periphery of the main body portion and extends from the main body portion toward an outer circumferential side; and the cover plate is provided with a second recess and a first recess, which are sequentially arranged from the inside to the outside at a periphery of the filling port, the main body portion is located in the second recess, and the welding portion is welded to a bottom surface of the first recess. According to the present application, the main body portion is located in the second recess, and the welding portion is welded to the bottom surface of the first recess. The second recess is configured to receive the electrolyte, so as to reduce the residual electrolyte on the bottom surface of the first recess, and the bottom surface of the first recess is welded to the welding portion of the sealing pin, so as to prevent the sealing pin from being welded to the side wall of the filling port, thereby improving the welding sealing performance between the sealing pin and the filling port.