Characteristics of carbon-coated graphite prepared from mixture of graphite and polyvinylchloride as anode materials for lithium ion batteries

A carbon-coated graphite is investigated as the negative electrode for Li-ion batteries. The carbon-coated graphite particles are prepared by simple heat-treatment of mixtures of graphite and poly(vinyl chloride), PVC, at 800–1000°C in an argon flow. The carbon coating reduces significantly the initial irreversible capacity of the graphite in a propylene carbonate-based electrolyte, by suppressing the solvated lithium ion intercalation, and also improves the initial charge–discharge coulombic efficiency. By carbon coating, the specific surface area of graphite particles is greatly increased. These findings can be explained by assuming that a turbostratic structure of PVC-carbon resists irreversible side-reactions which are controlled predominantly by active, edge surface sites.