A green method for the preparation of anode materials for lithium ion batteries

Here we demonstrate for the first time that an anode material for lithium ion batteries can be satisfactorily prepared by a green method. By selecting benign and easily recycled oxidants, solutions of H₂O₂ and Ce(SO₄)₂, the electrochemical performance of a natural graphite anode material can be markedly improved. Through thermogravimetric analysis, differential thermal analysis, X-ray photoelectron spectroscopy, high resolution electron microscopy and measurements of lithium capacity it was found that the surface structure of the natural graphite was modified with a dense layer of oxides, which could prevent the co-intercalation of solvent molecules. In addition, the stability of the graphite crystal was improved and the decomposition of electrolyte molecules was prohibited. Furthermore, a large number of nano-channels were introduced by oxidation, which favored lithium intercalation and de-intercalation. The reversible lithium capacity was enhanced from 251 to >330 mA h g^-1, and no capacity fading was observed in the first 10 cycles. This green method is also highly efficient and economical, the process can be performed below 60°C.