摘要
以钒基合金(Ti Cr)0.497V0.42Fe0.083为基体,添加30%(w)稀土系A2B7型合金(LaRMg)(NiCoAl)3.5为电催化活性材料,采用机械球磨改性制备了储氢合金复合电极材料,研究其储氢特性和电化学性能.X射线衍射(XRD)、扫描电镜(SEM)和透射电子显微镜(TEM)分析结果表明,随球磨时间增加(t=0,0.5,1,3,5,10h),复合材料颗粒逐渐细化,A2B7型合金颗粒分散并包覆在钒基合金表面上;当球磨时间t≥5h时,复合材料形成明显的复合纳米晶组织并伴有部分非晶化倾向,同时钒基合金BCC相结构的晶胞参数a和晶胞体积V均明显减小.合金储氢特性及电化学性能分析测试结果表明,铸态纯钒基合金的吸氢量为3.11%(w),而球磨复合材料的储氢量随球磨时间增加呈减小的规律,其最大储氢量为2.47%(w);球磨改性后,复合材料电极的电催化性能得到明显改善,当球磨时间t≥3h时最大放电容量达到425.8mAh·g-1,经100次充放电循环后该电极的容量保持率(C100/Cmax)为97%,表现出良好的电极循环稳定性.
Changes in phase structure,hydrogen storage and electrochemical properties of the（Ti Cr）0.497V0.42Fe0.083＋ 30%（w）（LaRMg）（NiCoAl）3.5 alloy after treatment by ball-milling for different time（t=0,0.5,1,3,5,10 h） were investigated systematically.X-ray diffraction（XRD）,scanning electron microscopy（SEM）,and transmission electron microscopy（TEM） showed that the particle size of the milled composite samples decreased gradually and the powder appears aggregated.The A2B7 alloy particles were uniformly dispersed and encapsulated on the surface of the V based alloy particles that were formed after increasing the ball-milling time.It was found that nanocrystalline composites were formed and partial amorphization occurred when the milling time was more than 5 h.The crystal parameter a and the cell volume V of the BCC phase structure in the composite both showed a decrease.Hydrogen storage capacity of the single V based alloy was 3.11%（w）,with an increase in milling time hydrogen storage capacity of the milled composites decreased and the maximum hydrogen absorption capacity at room temperature approached 2.47%（w）.Electrochemical studies showed that the electrochemical properties of the milled composite were enhanced and the maximum discharge capacity was 425.8 mAh·g-1.The cyclic stability of the composite electrode improved noticeably.After 100 charge-discharge cycles the discharge capacity retention rate C100/Cmax of the milled composite electrode was 97%,and it had a better cycle life than that of the A2B7 type alloy electrode.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2010年第9期2397-2404,共8页
Acta Physico-Chimica Sinica
基金
兰州理工大学博士基金资助项目~~
