Li-rich layered oxide single crystal with Na doping as a high-performance cathode for Li ion batteries

Although Li-rich layered oxides (LLOs) have high specific capacity over 250 mAh g−1, their large scale applications are hindered because of the release of oxygen and structural change during cycling. In this paper, Na-doped LLOs single crystal, Li1.1Na0.1Ni0.13Co0.13Mn0.54O2 (N-LLNCMO), has been prepared to combine the advantages of Na doping and single crystal structure. As cathode in Li ion batteries, N-LLNCMO shows a higher discharge capacity of 278.5 mAh g–1 at 0.2 C and capacity retention of 87.0% after 100 charge and discharge cycles. More importantly, N-LLNCMO cathode delivers a superior rate capability (150.1 mAh g–1 at 10 C) and the discharge capacity of undoped analog is only 122.4 mAh g–1. The improved electrochemical performances are closely related to single crystal structure and Na doping which possess more stable structure, pinning effect and enlargement of the channels for Li ions diffusion. This strategy with synergistic effect of single crystal structure and Na doping can be developed to next generation Li ion batteries with high performance.