Hydrogen absorption–desorption behavior of zirconium-substituting Ti–Mn based hydrogen storage alloys

Hydrogen storage properties of zirconium substituting Ti–Mn based Laves phase alloys with the formula Ti1−XZrXMn1.4 (X=0, 0.1, 0.2, 0.3 and 0.4) were evaluated by pressure-composition (PC) isotherm tests. Their crystallographic structures were identified by X-ray diffraction (XRD). The experimental results showed that their maximum hydrogen storage capacity (H/M, M=Ti1−XZrXMn1.4) increased with increasing X. The value of H/M for X=0.4 reached up to 2.916 which corresponds to 2.05 wt.% of hydrogen in the hydride, while the maximum reversible hydrogen storage capacity of the alloys appeared at X=0.1. The introduction of zirconium into the alloy did not cause any change in the phase constitution. C-14 type Laves phase was still predominant in the alloy while the lattice parameters a and c increased with increasing content of zirconium substituting for titanium. The introduction of zirconium increased the changes of entropy and enthalpy of hydrogen absorption. Activation tests showed that Ti0.9Zr0.1Mn1.4 alloy could react with hydrogen quickly under the condition of 273K and 9 atm of hydrogen.