Effect of SiO2-doped on microstructural evolution and hydrogen storage performances of AB2 type alloy

The influence of impurities (such as Si, O) on the properties of hydrogen storage alloys in industrial processes received extensive attention, yet the role of Si and O coexisting on the hydrogen absorption and desorption properties of AB2-type hydrogen storage alloys remains to be clarified. We investigated the doping of SiO2 on the microstructure and hydrogen storage properties of Ti-Mn based AB2-type hydrogen storage alloy. When a small amount of SiO2 (<1.0 wt%) was added, the hydrogen storage properties of the alloy did not change much and still maintained excellent cyclic stability, and the only difference was the plateau pressure of the alloys doped with SiO2 decreased. However, when excessive SiO2 (∼2.0 wt%) was added, the hydrogen storage plateau slope of the alloy increased sharply, and the hydrogen storage capacity decreased. It is ascribed that the formation of ZrO2 phase and the doping of Si with the SiO2 content increase, resulting in the lattice constant of the alloy increasing and the plateau pressure decreasing. These findings hold promising reference prospects for practical production.