Catalytically graphitized glass-like carbon examined as anode for lithium-ion cell performing at high charge/discharge rates

The influence of a long-time heat treatment of hard carbon in the presence of iron catalyst on its structural properties and electrochemical performance is concerned in terms of potential application as anode material for lithium-ion cell. Glass-like carbon spheres obtained by carbonization of phenol resin were catalytically graphitized by heat treatment at temperature 1000 °C in argon atmosphere for 20 h and 100 h. After this process iron was completely removed from the product of reaction. The original carbon was entirely useless as anode for Li-ion cell because of its extremely poor reversible capacity (54 mAh g−1). Due to heat treatment composite materials consisting of microcrystalline graphite admixed with turbostratic carbon were produced. Modified carbons were tested as anode materials using gradually increasing current density. Based on electrochemical measurements a mixed intercalation/insertion mechanism for storage of lithium ions was concluded. Discharge capacity of carbon heat treated for 100 h attained value of 276 mAh g−1 and its reversible capacity appeared to be better than that of flaky graphite upon discharging at current density in the range 50–250 mA g−1.