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 coating the inner core, the inner core comprises LimAxMn (1-y) ByP (1-z) CzO (4-n) Dn, the shell comprises pyrophosphate MP2O7, borate XaBbOc and carbon, the shell comprises one or more coating layers, and each coating layer independently comprises one or more of pyrophosphate MP2O7, borate XaBbOc and carbon. According to the positive electrode active material disclosed by the invention, the secondary battery has relatively high energy density and also has improved cycle performance, safety performance and/or rate capability. 本申请提供一种正极活性材料、其制备方法以及包含其的正极极片、二次电池及用电装置。所述正极活性材料包括内核及包覆所述内核的壳，所述内核包括LimAxMn1-yByP1-zCzO4-nDn，所述壳包括焦磷酸盐MP2O7、硼酸盐XaBbOc和碳，并且所述壳包括一层或多层包覆层，各层包覆层分别独立地包括焦磷酸盐MP2O7、硼酸盐XaBbOc和碳中的一种或多种。本申请的正极活性材料能使二次电池具有较高的能量密度以及兼顾改善的循环性能、安全性能、和/或倍率性能。