Abstract:
Graphite is a host material for lithium intercalation and can be used as an active anode material in rechargeable lithium cells. The battery
performances and cycling depends on the type and morphology of graphite. The advantage of natural graphite is the possibility of enhancing the
electrochemical intercalation by simple mechanical or chemical treatments. Sri Lanka natural graphite is found in various morphologies with
different structural and physical characteristics. The most abundant morphology, the shiny–slippery–fibrous graphite found in
Kahatagaha/Kolongaha mines, has a very high purity of over 98% and high crystallinity. Lithium has been electrochemically intercalated into
different morphologies of pure natural graphite as well as into treated graphite. The ball milling facilitates partial conversion of hexagonal into
rhombohedral phase, which increases structural defects lowering the tendency to solvent co-intercalation and exfoliation and increasing the
reversible capacity. Chemical treatments on graphite show improvements in reversible capacity. The mechanical ball milling and the chemical
oxidation in air and (NH4)2S2O8 are simple and effective methods to enhance the electrochemical intercalation of lithium ions into natural
graphite.
