LaNi_(5-x)Fe_x(x=1～1.8)合金相结构及电化学性能

Phase Structure and Electrochemical Properties of LaNi_(5-x)Fe_x(x=1～1.8) Alloy

研究了LaNi5-xFex(x=1.0,1.2,1.4,1.6,1.8)合金中Fe部分代替Ni对LaNi5型电极合金相结构及电化学性能的影响。结果表明:当x=1.0时,合金由LaNi5和La2Ni7相组成;当x=1.2时,开始出现(Fe,Ni)相;当x=1.6时,还开始出现La2Ni3相。随x增大LaNi5相逐渐减少、La2Ni7和(Fe,Ni)相逐渐增多。随Fe含量的增大,电极合金放电容量减小,扩散系数减小,交换电流密度呈先减小后增大的趋势,当x=1.4时,电极合金的交换电流密度达到最小值。Fe含量对合金电极高倍率放电性能HRD值的影响与对合金电极交换电流密度的影响趋势一致,这表明电极合金表面的电化学反应对合金的动力学性能影响更大。

The effect of Fe replacing Ni on the phase structure and electrochemical properties of LaNi5-xFex（x=1.0,1.2,1.4,1.6,1.8） alloy electrodes was studied. The results shows that the main phase LaNi5 decreases and the La2Ni7 phase increases when x increases from 1.0 to 1.8, in which （Fe, Ni） phase appears when x=1.2, and La2Ni3 phase appears when x=1.6. The increase of Fe content leads to the change of phase structure and the phase component, which results in the difference of electrochemical properties. The discharge capacity and the diffusion coefficient decrease with the increase of Fe content. But the exchange current density increases first and then decreases when Fe content increases. When x=1.4, the exchange current density of alloy reaches to the lowest. The high rate discharge ability （HRD） has a change tendency as the same as the exchange current density, which implies that the electrochemical reaction on the surface of alloy electrodes has a great influence on the kinetic property.