Improved Absorption and Desorption Kinetics of Mg–Ni–Ce Alloy Activated under Elevated Hydrogen Pressure

Abstract

The large-scale application of Mg as a hydrogen storage material has been limited by its slow absorption and desorption kinetics at moderate temperatures. Refining the microstructures is an effective way to improve the hydrogen storage performance. Aiming at improving the de-/absorption kinetics of Mg-based alloys by in situ formed superfine catalysts, Mg–7Ni4Ce (mass%) alloy has been prepared and activated by controlling the activation hydrogen pressure. The phase components, microstructure and hydrogen storage properties have been systematically investigated. It is found that an 18R-type long-period stacking ordered (LPSO) phase is formed in the eutectic region of as-cast Mg–Ce–Ni ternary alloy. The observed LPSO structure is a variant of Mg₁₂Ce rather than Mg. Abundant secondary phase particles are obtained in the as-activated alloy. For the sample which is activated at 300°C under 7.5 MPa hydrogen pressure, the particle size of secondary phase is much finer than that of the sample activated under 3 MPa hydrogen pressure. The sample activated under higher hydrogen pressure shows superior absorption and desorption kinetics.