Synthesis of layered xLi2MnO3·(1 − x)LiMnO2 nanoplates and its electrochemical performance as Li-rich cathode materials for Li-ion battery

Layered xLi2MnO3·(1 − x)LiMnO2 (x = 0.57, 0.48, and 0.44) nanoplates are firstly prepared by pyrolysis reducing the electrochemically inactive monoclinic Li2MnO3 nanoplates, which is synthesized via a solid-state reaction by using home-made MnO2 nanoplates as self-template. The obtained xLi2MnO3·(1 − x)LiMnO2 nanoplates have a diameter of ∼200 nm and thickness of ∼60 nm with high crystallinity and the transition metal layers parallel to the plate's radial direction. Although these xLi2MnO3·(1 − x)LiMnO2 nanoplates cause a longer Li+ diffusion distance, and then a lower reversible capacity as compared to the nanoparticle-like counterpart, the nanoplate-like morphology of these xLi2MnO3·(1 − x)LiMnO2 (especially with x < 0.5) are beneficial for retarding the layer-to-spinel phase transformation during the charge/discharge processes, and resulting in significant improvement of the cyclic stability. Moreover, the reduced reversible capacity caused by the longer Li+ diffusion distance of the nanoplate-like morphology can be offset by decreasing the x value, and the xLi2MnO3·(1 − x)LiMnO2 nanoplates with x = 0.44 performs a maximum reversible capacity as high as 270 mAh g−1 with a well cyclic performance. The present findings indicate that the cyclic performance and reversible capacity of xLi2MnO3·(1 − x)LiMnO2 can be improved by tailoring the particle's morphology and composition, and demonstrate a simple and effective strategy for the development of the Co/Ni-free Mn-based layered Li-rich cathode materials with good cyclic and high reversible capacity.