Battery monomer, battery and electric device

The utility model provides a battery monomer, a battery and a power utilization device, the battery monomer comprises an electrode assembly and a shell, the shell comprises a first wall part and two second wall parts, the first wall part is provided with a pressure relief part, the pressure relief part is provided with a nick groove recessed in a second direction, the pressure relief part is configured to be cracked along at least one part of the nick groove when the battery monomer is subjected to pressure relief, and the nick groove is provided with a second direction; in the first direction, the nick groove and the outer surface of any one of the two second wall parts are arranged at intervals. In the technical scheme of the embodiment of the invention, the nick groove is separated from the outer surface of the second wall part, so that when the electrode assembly expands and the second wall part deforms, the probability that the weak area of the pressure relief part is directly broken due to deformation of the second wall part is reduced, the probability of liquid leakage at the pressure relief part is reduced, and the reliability of the electrode assembly is improved. The reliability of the battery monomer is improved.