退火对低钴贮氢合金的影响

Effects of annealing treatment on low-Co hydrogen storage alloy

研究了850℃与1 050℃两种温度退火对多元替代低钴贮氢合金MlNi3.8Al0.27Mn0.36Co0.24Cu0.15Cr0.1Zn0.05Fe0.05的微观结构、组织以及电化学性能的影响。XRD分析表明退火降低了合金的晶格应力和缺陷,同时使得合金的单胞体积增大。电化学测试结果表明,退火合金的放电容量明显提高,其中1 050℃退火后合金的最大放电比容量达到315.3 mAh/g,比铸态合金提高25.9 mAh/g。退火使得合金的高倍率放电性能略有降低,但仍保持在96%以上。退火可获得与铸态合金不同的微观结构是合金循环稳定性提高的主要原因。

The effects of 850 ℃ and 1050 ℃ annealing treatments on the phase structure,microstructures and electrochemical properties of low-Co MINi3.8Al0.27Mn0.36Co0.24Cu0.15Cr0.1Zn0.05Fe0.06 hydrogen storage alloys were investigated. The results of XRD analyses indicate that annealing treatment reduces the lattice train and defects of the as-cast alloy, and improves the unit-cell volume. The electrochemical tests indicate that the annealed alloys, compared with as-cast alloy,show a higher discharge capacity,much better cycling stability, especially 1 050℃ annealed alloys whose discharge capacity increases to 315.3 mAh/g, 25.9 mAh/g more than as-cast alloy. High rate discharge property decreased a little after annealing but it could still reach to 96%. And the microstructures of annealed alloys are different from that of as-cast alloy, which is an important reason why the annealed alloys have good cycle stability.