Synthesis and hydrogen sorption properties of TiV(2−x)Mnx BCC alloys

• New activation process was investigated for TiV2−xMnx samples (0.2 ⩽ x ⩽ 0.9).
• Samples crystallize with a BCC structure and turn into FCC upon hydrogenation.
• Samples activated with new activation process absorb up to 3.4 wt.% of hydrogen.

We report here the effect of activation process of TiV2−xMnx samples (x = 0.2, 0.4, 0.6, 0.8 , 0.9). Crystal structures are investigated for the as-cast, hydrogenated and desorbed states. The as-cast samples crystallise with a Body Centered Cubic (BCC) structure, and the lattice parameter decreases as x increases in the TiV2−xMnx series. Upon hydrogenation, the BCC structure expands and turns into a Body Centered Tetragonal (BCT) structure for the monohydride phase and into a Face Centered Cubic (FCC) for the dihydride phase. Pressure–Composition-Isotherms (P–C–I) measurements were performed to study the thermodynamic of TiV2−xMnx alloys and their hydrogen capacities. The maximum hydrogen uptake is observed for TiV1.2Mn0.8 composition, which store 3.4 wt.% of hydrogen at 100 °C. The effect of a new activation process on the hydrogen storage capacities of these alloys is discussed.