Smooth and uniform black Mg-Ni hydrogen storage alloy films are successfully electrodeposited from N,N-dimethylformamide (DMF) solution with proper complexing agent and additive agent at potentiostatic electrolysis. And the mechanism of co-deposition is discussed. XRD results show that there is amorphous Mg-Ni phase and microcrystalline Mg phase in the electrodeposits. SEM images of the deposit and the EDS analysis show that grains of the alloy exist as glomeration. AAS analysis indicates that the molar fraction of Mg is up to 27.3%, and the maximum discharge specific capacity of the deposit is up to 172.4 mAh/g.

Key words: Mg-Ni alloy, hydrogen storage alloy, electrodeposition, N,N-dimethylformamide