Carbon-coated Ni20Si80 alloy-graphite composite as an anode material for lithium-ion batteries

A carbon-coated Ni20Si80 alloy-graphite composite has been studied as the anode for lithium-ion batteries. The composite is prepared by simple heat-treatment of a mixture of coal tar pitch and a Ni20Si80-graphite composite at 900 deg C and under argon. The Ni20Si80 alloy powders are synthesized by mechanical alloying. The composite demonstrates promising electrochemical properties such as high reversible capacity, excellent cycle performance, and sufficiently high initial charge-discharge coulombic efficiency. This suggests buffering and conductive actions on the main active material, viz., Ni20Si80 alloy, of the graphite. These two effects are strongly enhanced by the carbon coating treatment.