Superior De/Hydriding Kinetics and Cycling Stability of Mg-Ceal3@Ceh2 Nanocomposites

Efficient hydrogen storage is essential for the practical applications of hydrogen energy. Mg has been regarded as one of the most promising hydrogen storage materials to address this issue. However, the sluggish kinetics and high working temperature severely hinder its large-scale applications. Here, we facilely constructed Mg-CeAl3@CeH2 nanocomposites by ball-milling to improve the hydrogen storage kinetics and decrease the working temperature of Mg. X-ray diffraction analysis, along with selected area electron diffraction, revealed the formation of intermetallic compound Ce3Al during the de/hydriding process. Nano Ce3Al, CeAl3, and CeH2 modified Mg/MgH2 exhibit superior hydrogen absorption and desorption performance. For Mg-20wt.% CeAl3@CeH2 nanocomposite, the activation energies were reduced to 70.8kJ/mol H2 for hydriding and 84.6kJ/mol H2 for dehydriding, respectively. The hydrogen desorption peak temperature was lowered by about 77K for the Mg-20wt.% CeAl3@CeH2 nanocomposite compared with Mg. The addition of CeAl3@CeH2 composite also inhibits the growth of Mg/MgH2 grains. Mg-CeAl3@CeH2 nanocomposites exhibited robust nanostructure and superior hydrogen absorption and desorption cycling stability. The hydrogen capacity retention remained above 96% without de/hydriding kinetics degradation after over 20 cycles. This work provides a facile strategy to create catalyzed Mg-based nanocomposites to achieve superior hydrogen storage performance.