Annealing effects on structural and electrochemical properties of (LaPrNdZr)0.83Mg0.17(NiCoAlMn)3.3 alloy
Annealing effects on structural and electrochemical properties of (LaPrNdZr)0.83Mg0.17(NiCoAlMn)3.3 alloy
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DOI：
10.1016/j.jallcom.2008.03.084
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发表时间：
2009-03
影响因子：
6.2
通讯作者：
F. Li;K. Young;T. Ouchi;M. Fetcenko
中科院分区：
文献类型：
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作者：
F. Li;K. Young;T. Ouchi;M. Fetcenko
对稀土镁镍基合金(La0.205Pr0.392Nd0.392Zr0.012)0.83Mg0.17Ni2.97Co0.1Al0.2Mn0.03were进行了不同退火条件的研究。用X射线衍射仪和Rietveld分析测试了电化学循环前后合金的相结构。合金主要由Ce2Ni7-、CaCu5-、Ce5Co19-或CeNi3型相组成。相丰度随退火温度的不同而变化较大。压力-浓度等温线表明，随退火温度的升高，储氢量先增大后减小。电化学测试也显示出类似的趋势，最大放电容量从339mAhg(1173K)开始，增加到345mAhg(1198K)，然后下降到312mAhg(1273K)。Pr和Nd的加入在热处理后形成了具有CeNi3结构的新的AB3相，由于表面/电解液界面具有较低的转移电阻和较高的体扩散系数，因此具有更好的高倍率放电性能。
Rare-earth magnesium nickel based alloys (La0.205Pr0.392Nd0.392Zr0.012)0.83Mg0.17Ni2.97Co0.1Al0.2Mn0.03were studied with various annealing conditions. The phase structures of the alloys before and after electrochemical cycling were examined by x-ray diffraction and Rietveld analysis. The alloys mainly consisted of two or more phases from the group of Ce2Ni7-, CaCu5-, Ce5Co19-, or CeNi3-type phases. Phase abundance drastically changed with different annealing temperatures. As the annealing temperature increased, hydrogen storage capacity first increased and then decreased as indicated by the pressure-concentration isotherms. The electrochemical test showed a similar trend, resulting in a maximum discharge capacity which started at 339mAh/g (1173K), increased to 345mAh/g (1198K) and then decreased to 312mAh/g (1273K). The addition of Pr and Nd created a new AB3 phase with a CeNi3structure after annealing, which contributed to better high rate dischargeability due to both a lower transferring resistance at the surface/electrolyte interface and a higher bulk diffusion coefficient.