A modified graphite anode with high initial efficiency and excellent cycle life expectation

A new procedure was developed to prepare surface-modified graphite. First, spherical graphite (SG) particles were prepared through milling natural flake graphite (NFG). Then, surface-modified spherical graphite (MSG) was obtained by coating SG with a nanolayer of nongraphitic carbon. The SG exhibits better electrochemical performance than NFG, since there are significant decreases in the surface area and the probability of getting graphite basal planes parallel to the copper foil. It is also demonstrated that a nanolayer of nongraphitic carbon evenly covers the surface of SG. MSG with a core-shell structure shows higher initial coulombic efficiency and better cycle stability than SG because the carbon coating layer has improved its compatibility with electrolytes and protected the graphite against exfoliation.