Effects of Mg on the structures and cycling properties of the LaNi3.8 hydrogen storage alloy for negative electrode in Ni/MH battery
Effects of Mg on the structures and cycling properties of the LaNi3.8 hydrogen storage alloy for negative electrode in Ni/MH battery
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DOI：
10.1016/j.jallcom.2014.09.117
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发表时间：
2015-01
影响因子：
6.2
通讯作者：
Zhewen Ma;Ding Zhu;Chaoling Wu;C. Zhong;Qiannan Wang;Wanhai Zhou;Linshan Luo;Yucheng Wu;Yun-gui Chen
中科院分区：
文献类型：
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作者：
Zhewen Ma;Ding Zhu;Chaoling Wu;C. Zhong;Qiannan Wang;Wanhai Zhou;Linshan Luo;Yucheng Wu;Yun-gui Chen
采用高频感应熔炼(HFIM)工艺制备了LaNi3.8型LaNi3.8和La0.8Mg0.2Ni3.8储氢合金。这两种合金主要由三方相Ce5Co19型(R-3 mm)和六方相Pr5Co19型(P63/MMC)组成。La0.8Mg0.2Ni3.8合金中Ce5Co19型相和Pr5Co19型相的晶胞体积均小于LaNi3.8合金。与LaNi3.8相比，含镁La0.8Mg0.2Ni3.8合金具有较低的吸/脱附平台、较小的滞后和较高的储氢容量。La0.8Mg0.2Ni3.8合金电极表现出良好的活化能力，放电容量(373.1 mA/h g−1)高于LaNi3.8合金电极(184.0 mA/h g−1)。La0.8Mg0.2Ni3.8合金电极的容量衰减率(0.88 mA/h(g/次循环)−1)远低于LaNi3.8合金电极(1.32 mA/h(g/次循环)−1)，这归因于镁的加入抑制了LaNi3.8合金的氢致非晶化。此外，在含镁合金电极的充放电循环过程中，由于镁的牺牲，可以显著抑制La和Ni在碱性溶液中的溶解，从而使La0.8Mg0.2Ni3.8合金电极具有较好的循环稳定性和耐腐蚀能力。
The LaNi3.8-type LaNi3.8and La0.8Mg0.2Ni3.8hydrogen storage alloys were prepared by high frequency induction melting (HFIM) under helium atmosphere followed by annealing treatment. Either alloy mainly consists of a rhombohedral Ce5Co19-type phase (R-3 m) and a hexagonal Pr5Co19-type (P63/mmc) phase. The unit cell volume of either Ce5Co19-type or Pr5Co19-type phase in the La0.8Mg0.2Ni3.8alloy is smaller than that in LaNi3.8. The Mg-containing La0.8Mg0.2Ni3.8alloy has a lower absorption/desorption plateau, smaller hysteresis and a higher hydrogen storage capacity than those of LaNi3.8. The La0.8Mg0.2Ni3.8alloy electrode shows an excellent activation capability and a higher discharge capacity (373.1 mA h g−1) than those of the LaNi3.8alloy electrode (184.0 mA h g−1). The capacity decay rate of the La0.8Mg0.2Ni3.8alloy electrode (0.88 mA h (g cycle)−1) is much lower than that of the LaNi3.8alloy electrode (1.32 mA h (g cycle)−1), which is attributed to that the addition of Mg suppresses the hydrogen-induced amorphization of the LaNi3.8alloy. Moreover, during the charge–discharge cycling of the Mg-containing alloy electrode, the dissolutions of La and Ni in the alkaline solution can be suppressed remarkably due to the sacrifice of Mg, which correspondingly results in preferable cycling stability and an anti-corrosion capability of the La0.8Mg0.2Ni3.8alloy electrode.