Electrochemical hydrogenation of Mg76Li12Al12 solid solution phase

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The electrochemical hydrogenation of Mg-based solid solution phase with Mg76Li12Al12 composition was studied by various electrochemical methods. The Mg76Li12Al12Hx (0 < x < 74) hydride has a hexagonal crystal structure (P-6m2, a = 3.1485(1), c = 5.1111(2) A) in which the hydrogen atoms insert to octahedral voids. The reversible hydrogen storage capacity of these compounds reached 3.2 wt% H, corresponding to 865 mAh/g. After final charging/discharging cycles, the initial Mg76Li12Al12 solid solution phase was recovered, indicating that the electrochemical reactions are reversible. These observations are confirmed by X-ray powder diffraction (XRPD) method and scanning electron microscopy (SEM).