Nano-LiFePO4/MWCNT cathode materials prepared by room-temperature solid-state reaction and microwave heating

The precursors of LiFePO4 were prepared by room-temperature solid-state reaction using CH3COOLi, NH4H2PO4, FeC2O4 center dot 2H(2)O as raw materials. Citric acid was added to reduce the particle size of LiFePO4, and multiwalled carbon nanotubes (MWCNTs) were adopted to improve the electrical conductivity. The LiFePO4 samples were synthesized for a few minutes by microwave heating. X-ray diffraction and transmission electron microscope were used to characterize their structures and morphologies. The results showed that all samples had the same olivine phase structure. When both citric acid and MWCNTs were added, nanoparticles of LiFePO4 homogeneously coated on the MWCNTs. An electrochemical test showed that LiFePO4, with both citric acid and MWCNTs addition, demonstrated an excellent electrochemical capacity of 145 mAh/g at C/2 and stable cycle ability. Citric acid expansion reduced the particle size, thus reducing the length of diffusion or improving the reversibility of the lithium ion intercalation/deintercalation. MWCNTs functioned as a lead to connect the LiFePO4 particles and enabled active materials to transport lithium ions and electrons at fast rates.