Synthesis and characterization of sulfur-doped carbon decorated LiFePO4 nanocomposite as high performance cathode material for lithium-ion batteries

This is the first report where crystalline sulfur-doped carbon decorated LiFePO4 nanocomposite are employed as cathode material for lithium-ion batteries. The electrode has been synthesized via a sol-gel route, in which benzyl disulfide and oxalic acid are used as the sulfur and carbon source, respectively. Meanwhile, the as-synthesized sample is characterized by XRD, SEM, EDS mapping, TEM, Raman spectra, XPS and electrochemical techniques. The results reveal that the sulfur-doped carbon is uniformly coated on the surface of LiFePO4 without destroying the crystal structure of the bulk material. Moreover, both the electronic conductivity and defect level of the carbon clearly increase, as a consequence, the electron and Li-ion diffusion of the electrode is further improved. As a cathode material for lithium-ion batteries, it exhibits a more outstanding electrochemical performance, especially the rate capability and long cyclic performance. Thus, it can be drawn a conclusion that the sulfur-doped carbon coating approach is an effective method to improve the electrochemical performance of LiFePO4 and could be extended to modify other electrode materials for lithium-ion batteries.