Microstructural evolution and performance of hydrogen storage and electrochemistry of Co-added La0.75Mg0.25Ni3.5−xCox (x = 0, 0.2, 0.5 at%) alloys
Microstructural evolution and performance of hydrogen storage and electrochemistry of Co-added La0.75Mg0.25Ni3.5−xCox (x = 0, 0.2, 0.5 at%) alloys
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DOI：
10.1016/j.pnsc.2017.07.004
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发表时间：
2017-08
期刊：
影响因子：
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通讯作者：
W. Lv;Yufang Shi;Wanpeng Deng;Jianguang Yuan;Youhua Yan;Ying Wu
中科院分区：
文献类型：
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作者：
W. Lv;Yufang Shi;Wanpeng Deng;Jianguang Yuan;Youhua Yan;Ying Wu
研究了共掺La0.75Mg0.25Ni3.5−xCox（x = 0,0.2, 0.5 at%）合金的显微组织、储氢性能和电化学性能。XRD和rietveld细化结果表明，样品主要由（LaMg）Ni3、（LaMg） 2ni7和lani5相组成，Co取代Ni改变了相丰度，但没有改变相组成。随着Co含量的增加，（LaMg） 2ni7相的数量减少，而lani5相的数量增加，而（LaMg） ni3相的数量先增加后减少。该合金在298k时能平稳地可逆吸氢和解吸氢。当Co含量为0.2 at%时，吸氢容量达到最大值1.14 H/M，在298 K和323 K时，吸氢容量在第1分钟分别达到1.09 H/M和1.03 H/M。电化学性能测试结果表明，La0.75Mg0.25Ni3.5−xcox合金在2次循环内被完全激活，经过100次充放电循环后，la0.75 mg0.25 ni3.3 co0.2合金的循环稳定性接近63.7%，高于la0.75 mg0.25 ni3.0 co0.5合金的循环稳定性（S100= 60%）。因此，la0.75 mg0.25 ni3.3 co0.2合金具有最佳的储氢和电化学综合性能。
Microstructure, hydrogen storage and electrochemical performances of Co-added La0.75Mg0.25Ni3.5−xCox(x = 0, 0.2, 0.5 at%) alloys are studied. XRD and rietveld refinement results suggest that the samples are mainly composed of (LaMg)Ni3, (LaMg)2Ni7and LaNi5phases, Co substitution for Ni changes the phase abundance, but not the phase composition. With the rising of Co content, the amount of (LaMg)2Ni7phase decreases, but the amount of LaNi5phase increases, while the amount of (LaMg)Ni3phase firstly increases and then decreases. The alloys reversibly absorb and desorb hydrogen at 298 K smoothly. When Co content is 0.2 at%, the hydrogen absorption capacity reaches the maximum value of 1.14 H/M, and the absorption capacities reach 1.09 H/M and 1.03 H/M in the first minute at 298 K and 323 K, respectively. Electrochemical performance measurement results show that La0.75Mg0.25Ni3.5−xCoxalloys are completely activated within 2 cycles, and the cyclic stability of La0.75Mg0.25Ni3.3Co0.2alloy approaches 63.7% after 100 charge/discharge cycles, which is higher than that (S100= 60%) of La0.75Mg0.25Ni3.0Co0.5alloy. Thus, the La0.75Mg0.25Ni3.3Co0.2alloy exhibits optimum comprehensive properties of hydrogen storage and electrochemistry.