The reversible hydrogen storage performances of Mg₅₀Co₅₀ and Mg₅₀Co₄₅Pd₅ alloys with body-centered cubic phase in electrochemical system

The Mg₅₀Co₅₀ and Mg₅₀Pd₅Co₄₅ alloys with nano-crystalline body-centered cubic (BCC) structure were confirmed by means of XRD and TEM/SAED analyses. They are available in the anode of Ni-MH battery system, which can be reversibly charged and discharged with maximum capacity of 458 mAh g^-1. They exhibit greatly enhanced reversible hydrogen storage, differing from their tough dehydrogenation performances in solid-gas system [Y. Zhang et al., Journal of Alloys and Compounds 393 (2005) 147-153]. This phenomenon can be ascribed to the structural stability of Mg₅₀Co₅₀-based binary and ternary BCC alloys in the electrochemical reactions, and also the electro-catalysis activity. Introducing Pd into Mg₅₀Co₅₀ alloy lifts not only the initial discharge capacity, but also the high-rate discharge-ability. The exchange current density and hydrogen diffusion mobility can also be improved by the Pd additive in the ternary electrode alloys.