Improving the reversibility of the H2-H3 phase transitions for layered Ni-rich oxide cathode towards retarded structural transition and enhanced cycle stability

Although the layered Ni-rich LiNi x Co y Mn 1-x-y O 2 (0.7 <  x  < 1, 0 <  y  < 0.3) cathode materials are expected to deliver high capacity, their moderate cycle lifetime and thermal stability still hinder practical applications. There's often a tradeoff between high capacity and structure stability since more Li + ions delithiated during charging will leave the structure of the layered Ni-rich materials more vulnerable. Herein, we propose that improving the reversibility of H2-H3 phase transition for Ni-rich materials is effective to tackle this challenge. It has been confirmed that the generation of microcracks and structural transformations have been suppressed since the H2-H3 phase transition becomes reversible, while which shows little effect on capacity delivery. Consequently, using Ni-rich LiNi 0.9 Co 0.1 O 2 as the cathode material, the 100 th capacity retention cycling at 38 mA g −1 has been improved remarkably from 69.7% to 97.9% by adopting this strategy. Hence, it should be a novel solution to realize both high capacity and stable cyclability for the Ni-rich cathodes.