Hollow Structured LiFePO4/C Microspheres in situ Prepared by a One-Pot Template-Free Method as Cathode for LithiumIon Batteries

The effective control of the nanostructure is recognized as an effective method for improving the electrochemical performance of the LiFePO4 cathode; nevertheless, it is still a great challenge to simultaneously achieve high tap density and excellent electrochemical performance. Herein, we develop a hydrothermal method combined with a sintering process to synthesize monodispersed LiFePO4/C microspheres with an open channel interior. The microsphere assembled of ultrathin nanosheets shows a unique hollow structure with open channel which endows the hollow LiFePO4/C with a good balance of high specific surface area (28.9 m(2) g(-1)) and tap density (1.2 g cm(-3)), revealing prospect of the promising application. This sample with 2.6 wt% in-situ carbon coating exhibits a superior reversible capacity. At high current densities of 5 and 10 C, discharge capacities of 115 and 93.5 mAh g(-1) could be obtained, respectively, indicating excellent rate performance of the as-prepared hollow LiFePO4/C sample. The superior lithium storage performance should originate from the accelerated charge transfer and Li-ion diffusion from the unique hierarchical hollow microsphere structure, as well as from the improved electronic conductivity ascribed from the in-situ carbon coating. This work highlights that the structure-based design is an effective approach to achieve superior lithium storage performance together with high tap density for LiFePO4 cathode material.