The formation mechanism and electrochemical cyclic stability of the single-phase PrnMgNi5n-1(n = 2, 3, 4) hydrogen storage alloy
The formation mechanism and electrochemical cyclic stability of the single-phase PrnMgNi5n-1(n = 2, 3, 4) hydrogen storage alloy
复制标题
单相PrnMgNi5n-1(n=2,3,4)储氢合金的形成机理及电化学循环稳定性
DOI：
10.1149/2.0621610jes
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发表时间：
2016
影响因子：
3.9
通讯作者：
Han Shumin
中科院分区：
文献类型：
--
作者：
Ding Yanqiao;Zhang Lu;Li Yuan;Zhao Yumeng;Yang Shuqin;Ma Chunping;Liu Baozhong;Han Shumin
本工作以PrMgNi4和PrNi5为前驱体，通过严格控制分带烧结和退火工艺，制备了Pr2-MgNi9、Pr3-MgNi14和Pr4-MgNi19单相合金，并系统地研究了该合金的形成机理和容量衰退原因。结果表明，AB3、A2B7和A5B19型相间发生了连续的包晶反应，初始合金相为熔融的PrMgNi4相和固相PrNi5，包晶反应的形成温度分别为900℃、925℃和950℃。在深放电条件下，Pr4-MgNi19合金第100次循环的容量保持率达80.3%，优于Pr2-MgNi9(73.7%)和Pr3-MgNi14(77.5%)。通过计算[PrNi5]和[PrMgNi4]亚单位在充放电循环前后的体积差来研究合金颗粒的粉碎度，结果表明：Pr4-MgNi19合金的失配度较低(22.04%)，小于100次循环时Pr2-MgNi9(48.61%)和Pr3-MgNi14(30.00%)。X-射线粉末衍射结果表明，Pr(OH)3和Mg(OH)2的相丰度均随[PrNi5]/[PrMgNi4]的增加而降低，PrNiNi5 n−1(n=2，3，4)中Pr(OH)3和Mg(OH)2的相丰度均随[PrNi5]/[PrMgNi4]的增加而减小。
In this work, we prepared the single-phase Pr 2 MgNi 9, Pr 3 MgNi 14 and Pr 4 MgNi 19 alloys via strictly controlling the zoning sintering and annealing process with PrMgNi 4 and PrNi 5 precursors, and systematically studied the formation mechanism and capacity degradation causes of the alloys. It is found that the successive peritectic reactions, of which the initial alloy phases are the molten PrMgNi 4 phase and the solid phase PrNi 5, occurred among the AB 3, A 2 B 7 and A 5 B 19-type phases, and the peritectic reaction formational temperatures for the three single-phases are 900 C, 925 C and 950 C, respectively. Under deep discharge, the capacity retention rate for Pr 4 MgNi 19 alloy is up to 80.3% at the 100 th cycle, which is superior than Pr 2 MgNi 9 (73.7%) and Pr 3 MgNi 14 (77.5%). The pulverization degree of the alloy particle is studied by calculating the difference of the volume for [PrNi 5] and [PrMgNi 4] subunits before and after charge/discharge cycling, and the results indicate that the Pr 4 MgNi 19 alloy has lower mismatch degree (22.04%), which is smaller than Pr 2 MgNi 9 (48.61%) and Pr 3 MgNi 14 (30.00%) at the 100 th cycle. X-Ray Powder Diffraction (XRD) results suggest that the phase abundances of the hydroxides, Pr (OH) 3 and Mg (OH) 2 both decrease with increasing [PrNi 5]/[PrMgNi 4] in Pr n MgNi 5 n− 1 (n= 2, 3, 4).