Boron and magnesium ions co-doping synergistically enhances the electrochemical performance of nickel-rich cathode materials

Abstract

Nickel-rich ternary materials still suffer from defects of poor structure stability, fast capacity decay and poor rate performance, which inhibits their practical application in power batteries. Herein, a novel nickel-rich LiNi0.74Co0.14Mn0.12O2 cathode material co-doped with metallic and non-metallic ions was designed and prepared. The doped Mg2+ ions enter the lithium layers, reducing the Li+/Ni2+ cation mixing of the material; act as pillars, stabilizing the layered framework. While the doped B3+ ions occupy the tetrahedral sites, which expand the interlayer spacing and accelerate the diffusion of lithium ions. Furthermore, B3+ ions change the microstructure of the primary particles, alleviate the structural strain during the long cycle process and maintains the stability of the layered structure. Owing to the synergistic effect of Mg2+ and B3+ doping, the co-doped material exhibits superior electrochemical performance. A discharge capacity of 127.6 mAh·g−1 at 10 C, as well as a capacity retention of 91.33% after 100 cycles at 1C rate was achieved in the co-doped material. This metallic and non-metallic ion co-doping ternary material demonstrates its superiority compared with the single-element modified material.