Organic coating strategy with oxidized oxygen anion capture to suppress lattice oxygen evolution of Ni-rich cathode materials at high voltage

Ni-rich layered oxide has attracted widespread attention due to its high capacity of over 200 mAh<middle dot>g(-1) at 4.5 V. However, how to solve its lattice oxygen evolution problem during high-voltage cycling remains the major challenge nowadays. It is still important to design stable and efficient Ni-rich layered oxides. Herein, an organic coating strategy was proposed for this challenge. Specifically, (C3H3N)(n) (PAN) was employed as a proof-of-concept organic coating with better electro-negativity on LiNi0.8Co0.1Mn0.1O2 to inhibit the lattice oxygen evolution. The CN functional groups in the PAN coating can adsorb O alpha- (alpha < 2) and provide it with electrons for its reduction to stable O2-, thus inhibiting the continuous outward migration. As expected, in a voltage range of 2.7-4.5 V, the modified Ni-rich electrode displayed a high-capacity retention of 86.3 % after 200 cycles at 1C, 75.1 % after 350 cycles at 5C, and 83.1 % after 100 cycles at 1C and 55 degrees C. Furthermore, it also exhibited a high discharge specific capacity of 235.3 mAh<middle dot>g(-1) with a capacity retention of 75.5 % after 200 cycles under a cut-off voltage of 4.7 V. This innovative organic coating strategy presents new insights into suppressing the lattice oxygen evolution under high-voltage cycling by manipulating the surface chemistry of Ni-rich materials.