摘要
The effects of substitution of Sn for Co on the microstructure, hydrogen storage and electrochemical discharge capacity of La0.7Mg0.3Al0.3Mn0.4Co0.5-xSnxNi3.8 （x=0, 0.1, 0.2, 0.3 and 0.5） alloys were investigated using X-ray diffraction （XRD）, pressure composition isotherm （PCT） and electrochemical discharge cycle. XRD, scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS） tests showed that all of alloys are mainly composed of LaNi5 and MgNi2 phases, but when increasing the content of Sn in alloys, the LaNiSn phase appears and microstructure is refined. The PCT showed that increasing substitution of Sn for Co results in decrease of the maximum hydrogen storage capacity from 1.48% （x=0） to 0.85% （x=0.5）. The electrochemical tests indicated that the maximum discharge capacity decreases from 337.1 mA-h/g （x=0） to 239.8 mA.h/g （x=0.5）; however, the discharge capacity retention at the 100th cycle increases from 70.2% （x=0） to 78.0% （x=0.5）.
采用X射线衍射方法、压力-成分等温线、电化学放电循环研究了AB5型La0.7Mg0.3Al0.3Mn0.4Co0.5-xSnxNi3.8(x=0,0.1,0.2,0.3,0.5)合金中用Sn替换Co对其显微结构、储氢性能和电化学放电容量的影响。XRD、SEM及EDS测试结果表明,所有的合金都主要由La Ni5和Mg Ni2相组成,但随着合金中Sn含量的逐渐增加,出现LaNiSn相且显微结构得到细化。压力-成分等温线表明,随着合金中Sn含量的增加,合金的最大储氢容量从1.48%(x=0)降低到0.85%(x=0.5)。电化学测试结果表明,随着合金中Sn含量的增加,合金的最大放电容量从337.1 mA·h/g(x=0)降低到249.8 mA·h/g(x=0.5);充放电循环100次的放电容量保持率从70.2%(x=0)增加到78.0%(x=0.5)。
基金
Institute for Superconducting and Electronic Materials (ISEM)
University of Wollongong and Institute Nuclear and Energy Research (IPEN)
University of Sao Paulo for the financial support
National Council for Scientific and Technological Development – CNPQ – Brazil for the scholarships
financial support (CNPQ 472504/2010-0) granted to Julio Cesar Serafim CASINI
