合金化与Ti基储氢合金容量及活化性能关联

针对Ti-Zr基多元多相储氢电极合金,实验研究了Ni、Cr、V替代Mn对Ti基AB2型储氢合金容量和活化性能的影响.研究表明:在合金中增加Ni含量能够提高放电容量,但Ti-Ni相的过剩会降低合金容量;Ni的高活性和导电性加速氢扩散和电荷转移,改善合金活化性能;随Cr含量增加,合金容量先增后减,而活化性能先恶化后改善;V取代Mn提高合金容量,但当V超过一定计量后,将导致合金容量降低;V的高导电性改善合金电极的活化性能.

Relation of element substitution to discharge capacity and activation of Ti -Zr based AB2-type hydrogen storage electrode alloys

For Ti-Zr based AB2-type alloys with muti-composition and muti-phase, the effects of Ni, Cr and V on discharge capacity and activation property were experimentally studied. C14 Laves phase and its catalytic activation and phase proportion decide the changing trend of discharge capacity of the alloy electrodes. The capacity increased with increasing Ni and Ti-Ni phase contents, while the surplus Ti-Ni phase with low hydrogen storage capability led to the decrease of discharge capacity. Meanwhile, the high activation and electronic conductivity of Ni accelerated the hydrogen diffusion and charge transfer, which ameliorated the activation property of the alloys. Adding a small amount of Cr in the alloys produced protective oxide layer on the surface of alloy grains and reduced the consumption of hydrogen absorbing elements, which maintained the integrity of hydrogen storage phases and increased discharge capacity. But further increasing Cr content thickened the oxide layer, which hampered hydrogen diffusion and charge transfer and decreased discharge capacity. In addition, the existence of Cr oxide layer deteriorated the kinetic characteristics of electrode reaction and was not beneficial to the activation property of the alloy electrodes. Partial replacement of V to Mn increased discharge capacity , which was related to the formation of V-based solid solution phase with high hydrogen capacity and the dissolution of V into electrolyte on the interface of reaction. And while V content exceeded a certain stoichiometric value, discharge capacity of the alloys decreased due to the insufficient proportion of C14 phase that catalyzed V-based solid solution phase. Meanwhile, the high electronic conductivity of V improved activation property of the alloy electrodes.