Electrochemical charge and discharge properties for the formation of magnesium and aluminum hydrides

The electrochemical properties of Mg + 2LiH and Al + 3LiH are investigated by applying a Li-ion insertion and extraction system to form magnesium and aluminum hydrides. For MgH2 formation, the voltage–composition (VC) curve for Mg + 2LiH during charging exhibits a plateau voltage at 0.58 V, then the final composition is obtained with 1.05 mol Li extraction at 3.0 V. After the charging, the MgH2 phase is observed by XRD measurement. Therefore, MgH2 is produced from Mg and LiH by electrochemical charging. With respect to AlH3 formation, Al + 3LiH is charged at a plateau voltage of 0.81 V, which corresponds to the reaction of Al with hydrogen in LiH to form AlH3. And the final composition at 3.0 V is 0.6 mol Li. In the XRD profile after charging, the AlH3 phase is not detected.

Research highlights▶ Metal and lithium hydride are electrochemically charged to synthesis metal hydride. ▶ MgH2 is produced from Mg and LiH by the electrochemical charging. ▶ For the synthesis of AlH3, Al + 3LiH is charged at a plateau voltage of 0.81 V. ▶ For the decomposition of AlH3, AlH3 is discharged with the formation of LiH and Al.