The influence of alloy elements on the hydrogen storage properties in vanadium-based solid solution alloys

The effects of vanadium content and alloy elements (Mn and Ni) on the microstructure and hydrogen absorption/desorption properties in vanadium-based solid solution alloys were studied. The results showed that vanadium content had an obvious effect on hydrogen storage capacity. With the increase of vanadium content from 5 to 10 to 35 to 77.8 at.%, the hydrogen absorption capacity increased gradually from 1.30 to 1.55 to 2.88 to 3.11 mass%, and the hydrogen desorption capacity first increased from 0.52 to 0.70 to 1.79 mass%, but then decreased to 1.34 mass%. The reversible hydrogen storage capacities in these alloys were 40, 45, 62 and 43%, respectively. Furthermore, with the increase of vanadium content the pressure plateau became more distinctive and shifted steadily to a lower pressure level. The kinetics of hydrogen absorption in these alloys was relatively quick except in the case of the 35% vanadium alloy, which could not reach equilibrium even after 90 min. A small quantity of alloy elements Mn and Ni was able to increase the pressure plateau in the 35% vanadium content alloy and the hydrogen absorption capacity in the 5% vanadium content alloy, respectively, but had little effect on the hydrogen absorption kinetics. The microstructures in these alloys were also examined in order to provide a reasonable explanation of the results discussed.