Two kinds of novel materials, Mg-1.6mol%Ni-0.4mol%NiO-2mol%MF (MF=NbF5, CrF3), along with Mg-1.6mol%Ni-0.4mol%NiO for comparison, were examined for their potential use in hydrogen storage applications, having been fabricated via cryomilling. The effects of NbF5 and CrF3 on hydrogen storage performance were investigated. A microstructure analysis showed that, aside from the main phase Mg, Ni and NiO phases, NbO, MgF2 and Mg2Ni were present in all samples after ball milling, MgH2 and NbH2 were observed in all samples after absorption. The CrF3-containing composite exhibited a good PCT results and a low onset desorption temperature under 0.1 MPa. The NbF5-containing composite exhibited a low absorption temperature of 323 K, a high hydrogen storage capacity of 4.03wt% at 373 K under the hydrogen pressure of 4.0 MPa, and it absorbed 90% of its full hydrogen capacity in 2700 sec and 100% in 5100 sec, it desorbed more than 1.8wt% in 3600 sec under vacuum environment. The CrF3-doped sample exhibited a low onset desorption temperature of 543 K under 0.1 MPa, and a low hysteresis coefficient of 0.25 at 573 K, and lower than 0.2 when temperature was 623 K. NbO and NbH2 played an important role in improving the absorption and desorption performance.
Recent advances on the thermal destabilization of Mg-based hydrogen storage materials
