Research on hydrogen storage properties of Mg-3Ni-2MnO₂(wt.%) milled with nickel powders of different particle sizes

In this work, the hydrogen storage properties of nanocrystalline composite of Mg-3Ni-2MnO₂(wt.%) produced by mechanical milling under hydrogen pressure with two kinds of nickel powders, whose particle sizes are 75-170 μm and 20-50 nm, respectively, have been investigated. The results show that the composite (sample 2) milled with Ni nano-particles has better hydrogen storage properties than that (sample 1) milled with Ni micro-particles. After milled for 90 h, both composites can absorb hydrogen completely to its maximum value of 6.49 and 6.31 wt.%, respectively. Under 0.1 MPa hydrogen pressure, it takes 300 s for sample 2 to desorb 6.36 wt.% (98% of its maximum value) hydrogen in the temperature range of 285-310 °C, and it takes about 800 s for sample 1 to desorb 6.18 wt.% hydrogen in the temperature range of 300-310 °C.