A1、Cr元素对Mg2Ni储氢合金的协同改性研究：（Ⅱ）对电化学储氢性质的影响

The synergistic effect of AI and Cr addition on Mg2Ni Alloy： （Ⅱ） The electrochemical hydrogen storage property

采用烧结-机械球磨二步法制备了Mg2Ni、Mg1.7Al0.3Ni、Mg2Ni0.8Cr0.2、Mg0.8Al0.2Ni0.8Cr0.2储氢合金材料，研究了Al、Cr元素的加入对Mg2Ni储氢合金电化学储氢性质的影响。研究结果表明，适量Al元素的加入能改善储氢合金电极的电化学储氢性质，cr元素的加入能较好地改善循环稳定性，Al元素和cr元素同时加入会产生协同改性作用。认为Al、Cr元素协同改性作用的机理是：Cr元素的加入使得元素在合金化过程中避免形成A13Ni2非吸氢相，而形成Mg3A1Ni2吸氢相，因此储氢合金容量没有下降反而增加；A1元素能降低合金电极腐蚀的原因是形成了保护性表面氧化物Al2O3，Cr元素能大幅度提高合金电极吸傲氢循环稳定性的原因是由于cr原子半径比Ni原子半径大，发生取代后会引起晶格参数增大，增强了储氢合金抗粉化能力。

The Mg-based hydrogen storage alloys of Mg2Ni （A2B）, Mg1.7Al0.3Ni, Mg2Ni0.8Cr0.2 and Mgl.8Al1.2Ni0.8Cr0.2 were successfully prepared by sintering and mechanical alloying. Effects of A1 and Cr addition on electrochemical hydrogen storage property of Mg2Ni alloy were investigated. The results indicated that the addition of A1 improved the electrochemical hydrogen storage property of the hydrogen storage alloy electrode, and the addition of Cr improved the cyclic stability of the electrode, the synergistic effect was occurred when the elements of A1 and Cr was added simultaneous. The mechanism of the synergistic effect as follows： Cr could inhibit the formation of non -hydrogen-adsorption phase of A13Ni2, in addition, it will promote the formation of hydrogen-adsorption phase of Mg3AINi2, the discharge capability of electrode was increased instead of decreasing in theory; the reason for addition of A1 decreased the corrosion of electrode surface was that A12O3 was formed on its surface, Cr could dramatically improve the adsorption-desorption of hydrogen cyclic stability by reason of the diameter of Cr atom is bigger than Ni atom, crystal lattice was increased when the substitution occurring, subsequently, the anti-pulverization capability of hydrogen storage alloy was enhanced.