Surface Ni-rich engineering towards highly stable Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials

Li-rich layered oxide cathode materials (LLOs) are regarded as promising next-generation cathode candidate in high-energy-density lithium ion batteries due to their high specific capacity over 250 mA h g−1. However, LLOs always suffer from a series of severe issues, such as rapid voltage fading, fast capacity decay and bad cycling stability. In this work, Li1.2Mn0.54Ni0.13Co0.13O2-Li1.2Mn0.44Ni0.32Co0.04O2 (LLO-111@111/811) hybrid layered-layered cathode is constructed via facilely increasing surface Ni content. Profiting from this special design, the prepared LLO-111@111/811 cathode exhibits a remarkable specific capacity of 249 mA h g−1 with a high capacity retention of 89.3% and a high discharge voltage of 3.57 V with a voltage retention of 83.0% after cycling 350 times at 0.5 C. As a result, the specific energy of LLO-111@111/811 cathode is 887 Wh Kg−1 at 0.5 C and it keeps as high as 658 Wh Kg−1 after 350 cycles. LLO-111@111/811 also exhibits an initial high capacity of 169 mA h g−1 at a high rate of 5 C and maintains a good capacity retention of 90.0% after 200 cycles. This strategy can successfully improve structural stability, suppress capacity decay and restrain voltage fading of LLOs, which is beneficial for their practical application.