Influences of Mild Oxidation Treatment on the Structure and Electrochemical Behavior of Spherical Graphite

The effects of mild oxidation treatment on the crystal structure,morphology and electrochemical behavior of spherical graphite were investigated.The structure and morphology of the samples were characterized by XRD,Raman spectra and SEM analysis,respectively.The electrochemical behavior of the samples was studied using galvanostatic charge/discharge test,powder cavity microelectrode technique and slow scan rate cyclic voltammograms.The results indicate that structural defects in graphite particles and disordered degree of near surface region of graphite increase after modification,while the average in-plane crystallite domain size La and content of rhombohedral phase decrease.The graphite particles present irregular flake shape and some graphene sheets show flexual and sculptural margin.Electrochemical measures show that reversible capacity of modified graphite increases from 345.5 mAh/g to 381.4 mAh/g,and cycling performance is improved.During deintercalation process of the modified graphite,stage transformation from stage 1 Li-GICs(lithium-graphite intercalation compounds) to stage 2 Li-GICs begins to happen at lower voltage,compared with that of the raw graphite.