LiMnPO4 nanoplates with optimal crystal orientation in situ anchored on the expanded graphite for high-rate and long-life lithium ion batteries

Abstract

LiMnPO4 as a positive electrode material for lithium ion batteries has been considered as a potential replacement material for LiFePO4 because of its 20% higher redox potential than that of LiFePO4. However, its low electron and lithium ion migration rate make this material an unsatisfactory rate performance and cycle stability. In this work, we report a simple solvothermal route to synthesize a novel “face-to-face” structure for LiMnPO4/expanded graphene composites, which compose of LiMnPO4 nanoplatelets with (010) preferential crystal plane in situ grown on expanded graphite. It can be found that the expanded graphite effects on the preferential orientation and morphology of the LiMnPO4 nanoparticles. In the composites, the “face-to-face” contact structure between the LiMnPO4 nanoplatelets and expanded graphite sheets provides pathways for rapid electron transfer, meanwhile, the LiMnPO4 nanoplatelets with (010) preferential crystal plane improve the active sites and shorten the Li ion diffusion distances, resulting in excellent electrochemical performance. It displays an initial discharge capacity of 130 mAh g−1, and capacity retention of 100% after 200 cycles at 1 C. Even at a high rate of 10 C, it still shows a high discharge capacity (102 mAh g−1) and long-life cycle stability (∼72% capacity retention over 1000 cycles).