Carbon Coating of Magnesium via Thermal Plasma

Magnesium is a material of considerable interest for electrochemical as well as thermal energy storage. Carbon coated magnesium or magnesium nanopartciles emebedded in a graphitic matrix could provide solutions to some of the problems currently faced in these application areas. The current study was undertaken to develop Mg-C composites at a variety of length scales. The synthesis was achieved by co-feeding magnesium and methane into an RF thermal plasma reactor. This yielded carbonaceous material with magnesium particles 5-10 nm in size embedded in graphitic matrix. A further reduction down to 2-3 nm was possible but required reductions in the precursor feed rate. It was found that 2 wt.% carbon was sufficient to fully protect magnesium particles of approx. 260 nm in size. Light milling, however, disrupts the continuity of graphitic envelop and the particles then react both with oxygen and hydrogen. The potential of carbon coated magnesium as electrodes in rechargeable batteries are discussed.