Ti0.10Zr0.15V0.35Cr0.10Ni0.30+5wt％ LaNi5复合储氢合金的电化学性能与协同效应

摘要

为了改善钛钒基固溶体合金的电化学性能,利用两步电弧熔炼法制备复合储氢合金Ti0.10Zr0.15V0.35Cr0.10Ni0.30+5wt％ LaNi5,X-射线衍射(XRD)和场发射扫描电镜-能谱(FESEM-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C14 Laves相,复合过程中生成了第二相.电化学测试结果表明:复合合金电极的P-C-T特征、活化性能、最大放电容量、循环稳定性、低温放电性能和动力学特性均较母体合金有显著改善.复合合金电极的活化周期数为5,最大放电容量为353.9 mAh·g-1,233 K时低温放电能力为50.26％.该复合合金电极的最大储氢容量、平台压、电荷转移电阻和交换电流密度均存在协同效应;在任意循环、在高/低温下以及在高倍率放电过程中,该复合合金电极的放电容量均存在协同效应.%Ti0.10Zr0.15V0.35Cr0.10Ni0.30+5wt% LaNi5 composite hydrogen storage alloy was prepared by two-step arc melting in order to improve performance of Ti-V-based solid solution alloy. X-ray diffractometry (XRD) and field emission scanning electron microscopy-energy dispersive spectroscopy (FESEM-EDS) show that the main phase of the composite alloy is composed of V-based solid solution phase with a BCC structure and C14 Laves phase with hexagonal structure, while secondary phase also exists in the composite alloy. Electrochemical test shows that P-C-T properties, activation performance, maximum discharge capacity, cyclic stability, low temperature dischargeability and kinetics properties of the composite alloy are significantly improved. The activation cycle number and the maximum discharge capacity of the composite alloy are 5 cycles and 353.9 mAh·g-1, respectively,and the low temperature discharge ability is 50.26% at 233 K. Synergetic effect appears in the maximum hydrogen absorption capacity, plateau pressure, the charge-transfer resistance and the exchange current density. The synergetic effect of the discharge capacity appears in cycles, high/low temperature and high rate discharge process.