Surface modification of natural graphite particles for lithium ion batteries

The surface of natural graphite particles for the anode of dry-type polymer lithium ion batteries was modified by means of carbon coating and polyethyleneoxide (PEO) grafting. Carbon coating on graphite particles was achieved by a simple mixing of graphite particles with polyvinylchloride powders and heating up to 500°C under a nitrogen gas flow. The graphite particles obtained were coated with carbon homogeneously. The carbon layer was oxidized by heating at 400°C in static air to form carboxyl group and then PEO was grafted by esterification of the carboxyl group with terminal hydroxyl group of PEO. The dispersibility of the PEO-grafted particles in water was improved compared to that of untreated graphite particles.