Improvement of the electrochemical hydrogen storage performance of magnesium based alloys by various additive elements

Abstract

Mg1.5Ti0.3Zr0.1M0.1Ni (M = Al, B, C, Fe, Pd) type alloys were synthesized by mechanical alloying and their electrochemical hydrogen storage characteristics were investigated. While Al deteriorated the alloy initial discharge capacity, it improved the alloy cyclic stability. The reversibility in the presence of B was very poor. Addition of B increased the alloy initial discharge capacity but reduced the alloy capacity retention rate. The cyclic stability of Fe-including alloy was much better than that of C-including alloy, although both of them have almost the same initial discharge capacities. Both the alloy initial discharge capacity and the alloy cyclic stability were improved significantly in the presence of Pd. The analysis by the electrochemical impedance spectroscopy revealed that Fe increased the corrosion resistance of the alloy without degrading the capacity retention rate. The hydroxide barrier layer in the presence of Al was predicted to be more porous due to the possible high rate selective dissolution of the disseminated Al-oxides.