非晶态Mg-Ni系贮氢电极合金的结构与循环稳定性

The amorphous Mg-Ni system hydrogen storage alloys having high initial capacity are a new candidates of the negative electrodes materials for Ni/MH battery. However, their cycling capacity deterioration rate is too high to meet the requirement for practical applications so far. In this research project, the influence of the phase structure, chemical composition and corrosion behavior of the amorphous Mg-Ni system alloys on their cycling stability have been extensively studied in order to obtain a clearer understanding on the mechanism of the cycling capacity deterioration of the alloys, and find some alloys with better overall electrode properties by means of multi-component alloying. It is confirmed that the structure stability of the amorphous Mg-Ni system alloys is good during charge/discharge cycling, and the main factor controlling the cycling stability of the alloys was the oxidation and corrosion of the hydrogen-absorbing element of Mg. By partial substitution of Mg in the A side of amorphous Mg-Ni alloys with Ti, Zr, Cu, Fe, Al, Y, Cr, V, and the optimization of the Ni content in the B side of the alloys, it is found that the characteristics of the passivation layer on the alloy surface (including compactness and chemical stability in 6MKOH, etc.) played an important role on the preservation of Mg from further oxidation during cycling, and the partial substitution of Mg with Ti and Zr(Cr) together showed a good synergistic effect on the suppression of the alloy corrosion rate。 Among the alloys studied, the Mg35Ti5Zr5Ni55 alloy showed better overall electrode properties (with initial capacity of 332mAh/g and capacity retention rate of 64% after 50 cycles). Furthermore, based on the experiment data of corrosion current and capacity decay rate of the alloy electrodes versus cycling time, a mathematic formula representing the cycling capacity retention rate against cycling time was formulated, which can be used for calculation and expectation of the cycling stability of the amorphous Mg-Ni system hydrogen storage electrodes..

本项目拟着重就非晶态Mg-Ni系贮氢合金的结构稳定性、腐蚀行为及多元合金化对合金电化徘馓匦约把啡萘克ネ说挠跋旎平邢低车氖匝檠芯浚袢”匾幕∈荩⑾喙氐睦砺勰Ｐ停徊教岣叻蔷琈g-Ni系贮氢电极合金的综合性能奠定基础。本项目对于深化非晶态贮氢合金的研究有普遍意义、具有重要的学术价值和良好的应用前景。