Ti-V基固溶体/AB_5型镧镁基合金复合储氢材料的结构与电化学性能

Structure and Electrochemical Characteristics of Ti-V-based Solid Solution/AB_5-type La-Mg-based Alloy Composite Hydrogen Storage Material

两步电弧熔炼法制备Ti0.10Zr0.15V0.35Cr0.10Ni0.30+5wt%La0.85Mg0.25Ni4.5Co0.35Al0.15复合储氢合金,X射线衍射(XRD)和扫描电镜能谱(SEM-EDS)显示:复合储氢合金的主相是体心立方结构的钒基固溶体相和六方结构的C14Laves相,复合过程中生成了第二相.电化学研究表明:复合过程中存在明显的协同效应;在303 K时,复合合金电极的实际最大放电容量为361.8 mAh/g;在233 K时,复合合金电极的低温放电能力(LTD)是母体合金电极的4.05倍.与母体合金电极相比,复合合金电极的高倍率放电性能(HRD)提高了26.87%,电荷转移电阻(Rct)减小了37.25 m,同时交换电流密度(I0)增大了115.45 mA/g,合金体内氢的扩散系数(D)增大了6.13×10 10cm2/s.

Composite hydrogen storage alloy Tio.10Zr0.15V0.asCr0.10Ni0.30 ＋ 5wt% Lao.85Mg0.25Ni4.sCo0.35A10.15 was pre- pared by two-step arc melting. X-ray diffractometry （XRD） and scanning electron microscope-energy dispersive spec- troscopy （SEM-EDS） show that the main phase of the composite alloy consists of V-based solid solution phase with BCC structure and C14 Laves phase with hexagonal structure, while secondary phase also exists in the composite alloy Electrochemical studies show that distinct synergetic effect appears during the composite process. The real maximum discharge capacity of the composite alloy electrode is 361.8 mAh/g at 303 K, and the low temperature dischargeability （LTD） of the composite alloy electrode is 4.05 times as high as that of the matrix alloy electrode at 233 K. The high rate dischargeability （HRD）, the charge-transfer resistance （Rot） and the exchange current density （I0） of the composite alloy electrode are 26.87 % bigger, 37.25 mΩ lower and 115.45 mA/g higher than that of the matrix alloy electrode, respectively. The hydrogen diffusion coefficient （D） in the bulk of the composite alloy is 6.13×10-10cm2/s bigger than that of the matrix alloy.