Battery monomer, battery and electric device

The utility model provides a single battery, a battery and a power utilization device, the single battery comprises an electrode assembly, at least one positive pole piece and at least one negative pole piece are stacked to form a straight area, and at least one part of the positive pole piece and at least one part of the negative pole piece are stacked in the straight area along a first direction; the shell comprises a first wall part provided with a pressure relief part and two second wall parts, the two second wall parts are located on the two sides of the straight area in the first direction respectively, and the first wall part is located on one side of the electrode assembly in the second direction; a thickness dimension of the first wall portion in the second direction is greater than a thickness dimension of the second wall portion in the first direction. In the technical scheme of the embodiment of the invention, the pressure relief part is arranged on the first wall part, and the thickness of the first wall part is relatively increased, so that on one hand, the strength of the first wall part is favorably improved, the risk that the pressure relief part is damaged is reduced, the probability of liquid leakage is further reduced, and the reliability of the battery monomer is improved; and on the other hand, the shell can be formed by stamping through a die during manufacturing, the thickness of the first wall part is larger than that of the second wall part, the shell can be formed by stamping a plate with the same thickness as that of the first wall part, and the manufacturing difficulty of the shell is reduced.