Hydrogen desorption properties of MgH2/LiAlH4 composites

•Low milling time considerably improved desorption kinetics of composites.•Significantly improved desorption kinetics by adding LiAlH4.•Desorption mechanism changing Avrami–Erofeev n = 4 to Avrami–Erofeev n = 3.•Surface activation of sample is crucial for good desorption properties.

The hydrogen desorption properties of MgH2–LiAlH4 composites obtained by mechanical milling for different milling times have been investigated by Thermal Desorption Spectroscopy (TDS) and correlated to the sample microstructure and morphology analysed by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The MgH2–LiAlH4 composites show improved hydrogen desorption properties in comparison with both as-received and ball-milled MgH2. Mixing of MgH2 with small amount of LiAlH4 (5 wt.%) using short mechanical milling (15 min) shifts, in fact, the hydrogen desorption peak to lower temperature than those observed with both as-received and milled MgH2 samples. Longer mixing times of the MgH2–LiAlH4 composites (30 and 60 min) reduce the catalytic activity of the LiAlH4 additive as revealed by the shift of the hydrogen desorption peak to higher temperatures.