Positive electrode active material, preparation method thereof, positive electrode plate containing positive electrode active material, secondary battery and electric device

The invention provides a positive active material, a preparation method thereof, a positive pole piece containing the positive active material, a secondary battery and an electric device. The positive electrode active material comprises an inner core and a shell wrapping the inner core, the inner core comprises LimAxMnI-yByP1-zCzO4-nDn, and the shell comprises crystalline pyrophosphate LiaMP2O7 and/or Mb (P2O7). The invention relates to a catalyst comprising a shell comprising one or more coating layers, each coating layer independently comprising one or more of a crystalline pyrophosphate LiaMP2O7 and/or Mb (P2O7) c, a crystalline phosphate XPO4, a crystalline borate YpBqOr, and carbon, and the shell comprising one or more coating layers, each coating layer independently comprising one or more of a crystalline pyrophosphate LiaMP2O7 and/or Mb (P2O7) c, a crystalline phosphate XPO4, a crystalline borate YpBqOr, and carbon. According to the positive electrode active material disclosed by the invention, the secondary battery can have relatively high energy density, and improved cycle performance, safety performance and/or rate capability are taken into consideration.