Battery monomer, battery and electric equipment

The embodiment of the invention provides a battery monomer, a battery and electric equipment. The battery monomer comprises a shell, an electrode terminal and a protection piece, the shell comprises a first end wall, the electrode terminal is arranged on the first end wall, the protection piece covers the outer surface of the first end wall, the protection piece is provided with a first through hole, and the first through hole is used for exposing the electrode terminal. A cavity used for storing liquid is formed between the protection piece and the first end wall. The battery monomer has relatively high reliability.