Secondary battery monomer, secondary battery, formation method of secondary battery and power utilization device

The invention provides a secondary battery monomer, a secondary battery, a formation method of the secondary battery and a power utilization device, and relates to the field of lithium batteries. The secondary battery comprises a positive pole piece, a positive active material of the secondary battery comprises LiMPO4, and M comprises Mn and non-Mn elements; the formation method comprises the following steps: charging the secondary battery to a preset voltage, maintaining the preset voltage, and carrying out constant-voltage charging for a preset time, wherein the preset voltage is not lower than 3.9 V. The method can relieve the problems that the secondary battery containing LiMPO4 is easy to swell, low in battery capacity, short in service life and the like in the actual use process.