Improved electrochemical properties of amorphous Mg65Ni27La8 electrodes: Surface modification using graphite

Amorphous Mg65Ni27La8 alloy is prepared by melt-spinning. The alloy surface is modified using different contents of graphite to improve the performances of the Mg65Ni27La8 electrodes. In detail, the electrochemical properties of (Mg65Ni27La8) + xC (x = 0–0.4) electrodes are studied systematically, where x is the mass ratio of graphite to alloy. Experimental results reveal that the discharge capacity, cycle life, discharge potential characteristics and electrochemical kinetics of the electrodes are all improved. The surface modification enhances the electrocatalytic activity of the alloy, reduces the contact resistance of the electrodes and obstructs the formation of Mg(OH)2 on the alloy surface. An optimal content of graphite has been obtained. The (Mg65Ni27La8) + 0.25 C electrode has the largest discharge capacity of 827 mA h g−1, which is 1.47 times as large as that of the electrode without graphite, and the best electrochemical kinetics. Further increasing of graphite content will lead to the increase of contact resistance and activation energy for charge-transfer reaction of the electrode, resulting in the degradation of electrode performance.