Synthesis of high-performance LiFePO4/C composite with a grape hunch structure through the hydrothermal method

摘要

The LiFePO4/C composite with a grape bunch structure was synthesized through the hydrothermal method at 170 °C for 7 h and followed by being fired at 750 °C for 4 h. Commercial Li2CO3, (NH4)2Fe(SO4)2·6H2O, and (NH4)2HPO4 were used as raw materials. Glucose was used as in situ coating carbon source, and the hydroxylated MWCNTs were used as connecting carbon wires which could be embedded into the carbon coating to form a uniform grape bunch structure. The resultant samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), energy dispersive spectrometry (EDS), elementary analysis (EA), Raman spectroscopy, and electrochemical tests. The results show that the grape bunch structure with a low disordered/graphene (D/G) ratio was found to be well dispersed in the LiFePCVC composite, and a three-dimensional carbonaceous network was formed which could enhance the electronic conductivity of the LiFePO4/C composite remarkably. The resultant LiFePCVC composite shows a high discharge capacity of 160.3 mAh g~(-1) at 0.1 C and 110.9 mAh g~(-1) even at 10 C, and the cycling capacity retention rate reaches 99.6 % over 60 cycles. Besides, it also exhibits high conductivity, good reversibility, and excellent stability in EIS and CV tests.