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在氩气气氛和1173 K保温条件下对La0.63Gd0.2Mg0.17Ni3.1Co0.3Al0.1储氢合金进行不同时间(t=8～168 h)的热处理,采用电感耦合等离子发射光谱(ICP)、X射线衍射(XRD)、电子探针显微分析方法(EPMA)和电化学测试分析方法对比研究了退火时间对合金显微组织演化和电化学性能的影响。研究结果表明,铸态合金组织由Ce2Ni7型、Gd2Co7型、Pr5Co19型、PuNi3型和CaCu5型相组成,其Ce2Ni7型相的丰度为78.9%,随退火时间的延长,退火合金中Ce2Ni7型相的丰度逐渐增加,当退火时间t=168 h时其相丰度达到94.5%,Ce2Ni7型相结构的晶胞参数和晶胞体积随退火时间增加而减小。电化学测试分析表明,退火合金电极的电化学性能与Ce2Ni7型相的丰度有密切关系,退火时间对合金电极的活化性能影响不大,但合金电极放电容量随退火时间的延长逐渐提高,当t=168 h时,合金电极放电容量达到最大值386.8mAh.g-1;退火时间对合金电极循环稳定性的提高和改善有不同程度的影响,当退火时间t=16～168 h时,经100次充放电循环后,其电极容量保持率S100=90.3%～91.5%。热处理能有效改善合金电极电化学反应的动力学性能,但不同退火时间对合金电极的高倍率放电性能影响不明显。
La0.63Gd0.2Mg0.17Ni3.1Co0.3Al0.1 hydrogen storage alloys were heat-treated at different time (t = 8 ~ 168 h) under argon atmosphere and 1173 K heat preservation. Inductively coupled plasma atomic emission spectrometry (ICP) , X-ray diffraction (XRD), electron probe microanalysis (EPMA) and electrochemical test methods were used to study the effect of annealing time on the microstructure evolution and electrochemical performance of the alloy. The results show that the as-cast alloy consists of Ce2Ni7, Gd2Co7, Pr5Co19, PuNi3 and CaCu5 phases, and the abundance of Ce2Ni7 phase is 78.9%. With the increase of annealing time, the as-cast Ce2Ni7 phase The abundance gradually increases. When the annealing time is 168 h, the phase abundance reaches 94.5%. The unit cell parameters and cell volume of Ce2Ni7 phase decrease with the increase of annealing time. Electrochemical tests show that the electrochemical properties of the annealed alloy electrode are closely related to the abundance of the Ce2Ni7 phase. The annealing time has little effect on the activation performance of the alloy electrode. However, the discharge capacity of the alloy electrode gradually increases with the annealing time. When At 168 h, the discharge capacity of the alloy electrode reached the maximum value of 386.8 mAh.g-1. The annealing time had an effect on the improvement and improvement of the cycling stability of the alloy electrode. When the annealing time was between 16 and 168 h, After 100 cycles of charging and discharging, the electrode capacity retention S100 = 90.3% -91.5%. Heat treatment can effectively improve the electrochemical performance of the alloy electrode kinetic performance, but different annealing time on the high rate discharge alloy electrode performance is not obvious.