Chemical oxidation: A route to enhanced capacity in Li-ion graphite anodes

Chemical oxidation of graphite powder by the strong oxidative agents ammonium peroxysulfate and hot, concentrated nitric acid was examined as a way to enhance the capacity of graphite anodes in Li-ion cells. Chemical oxidation increased the reversible capacity obtained during cycling from 370 to 430 mAh/g, whereas the irreversible capacity accompanying the first intercalation cycle was reduced. Fourier transform infrared spectroscopy was used to investigate the effects of chemical oxidation on the surface of the graphite. Slow-scan cyclic voltammetry was applied in order to detect the origin of the extra capacity (where x > 1 in LixC6) associated with oxidized graphite powder.