Carbon-coated graphite for anode of lithium ion rechargeable batteries: Graphite substrates for carbon coating

Abstract

Anode performance in lithium ion rechargeable batteries (LIBs) was studied on four kinds of graphite powders, including synthetic graphite. Carbon-coated synthetic graphite gave a smaller irreversible capacity of about 20 mAh g −1 and a better cyclic performance in an electrolyte solution of EC/DMC than natural graphite, though its discharge capacity of about 300 mAh g −1 is a little smaller than natural graphite. Even in a PC-containing solution as EC/PC = 3/1, carbon-coated synthetic graphite had almost the same anode performance as in the solution without PC. Carbon coating of above 5 mass% on graphite particles was found to be effective to improve the anode performance at a low temperature of −5 °C, high retention in discharge capacity of about 90% being obtained. On both natural and synthetic graphite powders, carbon coating by the amount of 3–10 mass% at a temperature of 700–1000 °C was found to be optimum for the improvement of anode performance in LIBs, to have a lower irreversible capacity and higher retention in discharge capacity at −5 °C than without carbon coating.