Improving the Cyclic Stability of V–Ti–Mn bcc Alloys Using Interstitial Elements

Abstract

The effect of nitrogen interstitial atoms on the cyclic stability of V_0.37Ti_0.33Mn_0.3 was investigated. V_0.37Ti_0.33Mn_0.3 with and without nitrogen were hydrogenated and dehydrogenated for 100 times. During hydrogen cycling, the hydrogen absorption plateau pressure of both samples decreased significantly but the desorption plateau pressure stayed the same resulting in smaller hysteresis at higher cycle. Their reversible hydrogen storage capacity progressively diminished with increasing cycle number. At the first cycle, V_0.37Ti_0.33Mn_0.3 without nitrogen absorbed more hydrogen than V_0.37Ti_0.33Mn_0.3 with nitrogen but at the 100th cycle the situation was reversed; V_0.37Ti_0.33Mn_0.3 with nitrogen showed a higher reversible hydrogen storage capacity. This result strongly suggests that nitrogen interstitial atoms somehow retard the degradation of the hydrogen storage capacity of V_0.37Ti_0.33Mn_0.3.