Nonstoichiometric amorphous Mg 2 Ni 1.3 alloys were synthesized by mechanically milling crystalline Mg 2 Ni alloy with Ni powders. In comparison with the stoichiometric material, the nonstoichiometric Mg 2 Ni 1.3 phase showed a higher discharge capacity because of the amorphization of the alloy. Surface modification with graphite was also carried out for further improvement of its electrode performance. The coated powders showed a better cyclic stability because the graphite protected the Mg from oxidation. The rate capability (RC) and discharge capacity of electrodes was also markedly improved with graphite coating due to the excellent electrical conductivity and electrocatalytic activity of graphite.