【作者】 张秀飞；

【导师】 赵增祺； 闫慧忠；

【作者基本信息】 内蒙古科技大学 ， 材料学， 2010， 硕士

【摘要】 新型La-Fe-B系贮氢合金是一种“绿色”环保的稀土功能材料,具有较好的贮氢特性和较低的成本,综合电化学性能与传统LaNi₅型合金相当,可以不用价值较高的Co,同时含有价值低廉的Fe元素,成本比商品LaNi₅型贮氢合金低10-40%,可以开发出满足电池不同需求的各种贮氢电极材料。La-Fe-B系贮氢电极材料有着广阔的市场前景和显著的经济社会效益预期,具有重大的开发价值。元素替代法是改善贮氢合金性能的主要途径之一。本文研究了Nd部分替代La15Fe14Ni64Mn5B2合金中的La对材料结构和性能的影响。采用中频感应熔炼-快淬法制备了La_15-xNd_xFe₁₄Ni₆₄Mn₅B₂（x=0、2、4、6）贮氢合金,在一定的温度和压力下退火处理。X射线衍射（XRD）分析表明,合金由LaNi₅相、（Fe,Ni）相和La₃Ni₁₃B₂相组成。Nd替代La没有改变相组成,但衍射峰略向高角度方向位移。扫描电镜（SEM）及能谱（EDS）分析结果与XRD分析的相组成结果一致。适量的Nd替代La能够改善P-C-T的平台性能。电化学测试表明,La_15-xNd_xFe₁₄Ni₆₄Mn₅B₂ （x=0、2、4、6）贮氢合金的放电容量、高倍率放电能力（HRD）随x值的增大先增加后减小,x=2合金电极的放电容量最大(302 mAh·g^-1),HRD也最大（65.6%）。Nd替代La对合金的循环性能有所改善。退火热处理改善了La_15-xNd_xFe₁₄Ni₆₄Mn₅B₂（x=0、2、4、6）贮氢合金电极的活化性能,提高了放电容量和高倍率放电性能,但电极循环稳定性下降。更多还原

【Abstract】 La-Fe-B system hydrogen storage alloys with an good electrochemical performance like LaNi5 type alloys are a new type of rare earth function material, which adopts Fe,. Compared with LaNi5, La-Fe-B system hydrogen storage alloys have a cost lower 10-40% due to the Co-free. Various hydrogen storage electrode materials could be developed to meet different demands. With a promising market and remarkably economical and social anticipation, this new type of La-Fe-B hydrogen storage electrode material deserves deeper research.Element substitution is a one of the methods for further research aiming to ameliorate hydrogen storage material’s electrochemical performance. In this paper, La₁₅Fe₁₄Ni₆₄Mn₅B₂ is substituted its La by Nd so as to observe element Nd’s effect on the alloy’s phase structure and electrochemical performance.Hydrogen storage alloys La_15-xNd_xFe₁₄Ni₆₄Mn₅B₂（x=0,2,4,6） were prepared by medium frenquency induction melting and quick-quenching. The alloys were tested by X-ray diffraction to identify their phases. There is no new phase although La is partly replaced by Nd except for slightly movement of diffraction peaks to high angle direction. Alloys’Surfaces are also observed by SEM and compositions are determined by EDS. Results show there are three phases in alloys: LaNi₅, （Fe,Ni） and La3Ni13B2. La_15-xNd_xFe₁₄Ni₆₄Mn₅B₂（x=0,2,4,6） alloys electrodes were tested for eletrochemical performances. The highest capacity appears when x equals 2, then maximum capacity declines with increasing x. Small amount of Nd substitution for La could broaden plateau of discharge curve and improve electrode’s P-C-T curve plateau. Nd substitution for La also provides some improvement for electrode’s cycle performance. Alloy has a better HRD performance when x=2, but it declines as x increases. Generally speaking, small amount of Nd substitution for La has a positive effect on properties of La₁₅Fe₁₄Ni₆₄Mn₅B₂ alloy electrode.Anealing reduces numbers of activating, increases highest capacity, distinct enhances high rate discharge ability. But anealing also causes adverse effect on cycling performance.更多还原