Abstract: Correlation among preparation method, crystal structure, morphology and electrochemical performance of graphite with a slightly expanded interlayer were investigated. The structure and morphology of the samples were characterized by XRD and SEM analysis, respectively. The specific surface area (BET) and tap density were tested by the related equipments, The electrochemical behavior of the samples was studied using galvanostatic charge/discharge test, cyclic voltammograms, and electrochemical impedance spectra. The results indicate that average interlayer distance d₀₀₂ of modified graphite expands slightly, and average in-plane crystallite size La and Lc decrease, while spherical graphite particles become smoother. Electrochemical measures show that the initial columbic efficiency of graphite increases from 91.6% to 92.7%, and reversible capacity increases from 345.5 mAh/g to 379.8 mAh/g, while both cycling performance and rate discharge capacity are improved. The intercalation potential of modified graphite is mild increased, lithium-ion can deintercalate from graphite more easily, and the electrochemical reversibility of graphite is improved, compared with that of the raw graphite. The improvement can be ascribed to the reduction of activation energy of deintercalation reaction for modified graphite.

Key words: anode material, flake graphite, electrochemical performance, rate capacity, graphite intercalation compounds