The natural graphite was processed with technology of intercalation compounds (GIC), coated with precursor of soft carbon, and heated under inert gas. The interlayer space of the sample was increased, and the room for expanding of the sample was reserved. The improving method of increasing the interlayer space and reserving room for expanding has been found successfully, on condition that the changes of the diameter of carbon hexagonal layer and the particle size were not obvious. The analysis showed that there were a lot of oxygen-containing functional groups on the surface of GIC. In the process of GIC being coated with soft carbon, the recovery of the interlayer space and room for expanding was blocked by the reaction between those functional groups and petroleum pitch, and by the gas emission resulted from GIC pyrogenation. Using this sample as anode material of lithium-ion batteries, the reversible capacity changed little, but the rate discharge performance and cycle performance were improved remarkably. This was because of the increasing of the interlayer space and reserving room for expanding resulted in the enlargement of Li-ion diffusion path and the decrease of the coating layer damage.

Key words: interlayer space, lithium storage, natural graphite, graphite intercalation compound, carbon coating