A method for coating an active material with carbon to form an electrode material is disclosed, comprising: exposing olivine or nasicon to a carbon source gas in a furnace; and heating the carbon source gas to deposit carbon thereon. The carbon source gas, which may be mixed with an inert gas, generally decomposes between 100.degree. C. and 1300.degree. C. to generate carbon material. The amount of coated carbon on the olivine or nasicon is preferably <15 wt %, and more preferably about 4 wt % or less. Also disclosed is a battery comprising: a positive electrode comprising the inventive electrode material; a negative electrode; and an electrolyte.