稀土元素对Ti0.26Zr0.07V0.24Mn0.1Ni0.33贮氢合金微观结构和电化学性能的影响

本文研究了稀土元素对Ti0.26Zr0.07V0.24Mn0.1Ni0.33合金的微观结构和电化学性能的影响。结果表明,Ti0.26Zr0.07V0.24-xMn0.10Ni0.33REx(RE=Ce,Nd,Gd;x=0.01)合金均有V基固溶体相和C14型Laves相两相组成。合金中两相的晶格参数随加入稀土元素的不同而发生变化。稀土元素部分取代可改善合金电极的活化性能。然而,对合金电极的其他性能影响因元素种类不同而各异。Ce取代增大了合金电极的最大放电容量,Nd元素可以有效改善合金的高倍率放电性能。工作温度对合金电极的放电容量影响较大,Nd和Gd在333 K最大放电容量可达426和465 mAh.g-1。过高的温度使其循环容量衰减加剧。

Effect of Rare Earth Element Substitution for Vandium on Microstructures and Electrochemical Properties of Ti0.26Zr0.07V0.24Mn0.1Ni0.33 Alloy

The effect of rare earth element substitution on microstructures and electrochemical properties of Ti_0.26Zr_0.07V_0.24Mn_0.1Ni_0.33 alloys was studied. It is found that these alloys are composed of V-based solid solution with BCC structure and C14 Laves phase with hexagonal structure. The cell volumes of BCC phase and C14 Laves phase are different with the amount and type of rare earth elements substitution. Rare earth elements substitution can improve the activation characteristics of the Ti_0.26Zr_0.07V_0.24Mn_0.1Ni_0.33 alloy electrode. However, the effect on the other performances of the alloy electrode is different with the different rare-earth elements substitutions. Cerium substitution can enhance the maximum discharge capacity of the alloy electrode with charge-discharge current density of 60 mA·g^-1, and neodymium can improve the high-rate discharge ability(HRD) of the alloy electrode. The discharge capacity of the alloys is quite sensitive to temperature. The maximum value of the discharge capacity for the alloy electrodes with rare-earth elements neodymium and gadolinium substitution is 426 mAh·g^-1 and 465 mAh·g^-1, respectively, and then the discharge capacity degrades at excessively high temperature.