研究了铸态及退火（940℃、8h）La0.75Mg0.25Ni3.5Si0.10储氢合金相结构,及在30、45、55和70℃环境温度下电化学性能,包括放电容量、寿命、高倍率和自放电行为。X射线衍射分析表明,两合金均为La-Ni5、（La,Mg）2Ni7和（La,Mg）Ni3相组成的多相结构,退火处理使LaNi5和（La,Mg）Ni3相减少,（La,Mg）2Ni7相增多,但两合金主相均为LaNi5。研究发现,铸态和退火态合金活化性能都较优异,最大放电容量均随测试温度升高而减小,并且退火处理能提高每个温度点的放电容量,70℃高温下最为显著,合金放电容量从238.4mAh/g增加到342.5mAh/g。随温度升高,铸态合金的高倍率放电性先增大后减小,而退火合金高倍率放电性随温度升高单调增加。合金的荷电保持率随温度升高而降低,退火处理可提高各个温度点的荷电保持率。
The discharge capacity,the cycle life,the high-rate dischargeability and the self-discharge characteristics of the as-cast and annealed（940℃,8h） La0.75Mg0.25Ni3.5Si0.10 alloys were investigated at 30,45,55 and 70℃,respectively.The results analyzed by X-ray diffraction（XRD） showed that both alloys had multiphase structures containing LaNi5,（La,Mg）2Ni7 and（La,Mg）Ni3 phases.The LaNi5 and（La,Mg）Ni3 phases decreased while the（La,Mg）2Ni7 phases increased after annealing treatment,but the main phases of both alloys were all LaNi5.It is found that the activation characteristics obtained at every test temperature were all excellent in both alloys,but for each alloy the maximum discharge capacity decreased with the temperature increasing,and annealing treatment can improve this,especially at 70℃,the maximum discharge capacity increased from 238.4 to 342.5mAh/g.The high-rate dischargeability of the as-cast alloy increased first and then decreased.However,the high-rate dischargeability of the annealing alloy increased monotonously with the temperature increasing.The charge retention of both alloys decreased with the temperature increasing,and the annealing treatment improved the charge retention at every test temperature.
参考文献
| [1] | Hu WK.;Jeon SW.;Lee JY.;Kim DM. .Effect of annealing treatment on electrochemical properties of Mm-based hydrogen storage alloys for Ni/MH batteries[J].Journal of Alloys and Compounds: An Interdisciplinary Journal of Materials Science and Solid-state Chemistry and Physics,1998(1/2):255-264. |
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