(浙江大學(xué) 材料科學(xué)與工程系, 杭州 310027)
摘 要: 系統(tǒng)研究了溫度對(duì)La0.7Mg0.3Ni2.875Co0.525Mn0.1貯氫合金電化學(xué)性能尤其是電化學(xué)動(dòng)力學(xué)性能的影響。結(jié)果表明： La0.7Mg0.3Ni2.875Co0.525Mn0.1合金由 (La, Mg)Ni3相和LaNi5相構(gòu)成。 合金的最大放電容量隨著溫度升高從-20℃時(shí)的277.5mAh/g增加到30℃時(shí)的406.2mAh/g。 隨著溫度升高， 合金放電平臺(tái)電位逐漸變負(fù)， 放電過電位逐漸減小，合金電極的極化減弱。 高倍率性能、 交換電流密度、 氫的擴(kuò)散系數(shù)研究表明合金的電化學(xué)動(dòng)力學(xué)性能隨著溫度升高不斷提高。 該合金的氫擴(kuò)散活化能為17.6kJ/mol。
關(guān)鍵字: 貯氫合金; 溫度特性; 電化學(xué)性能; 動(dòng)力學(xué)
La-Mg-Ni-Co-Mn hydrogen storage electrode alloy
LI Shou-quan,GE Hong-wei, LEI Yong-quan
（ Department of Materials Science and Engineering,
Zhejiang University, Hangzhou 310027, China）
Abstract: Effects of temperature on the electrochemical properties of the La0.7Mg0.3Ni2.875Co0.525Mn0.1 hydrogen storage electrode alloy were systematically investigated, particularly for the electrochemical kinetic properties. The results indicate that the La0.7Mg0.3Ni2.875Co0.525Mn0.1 alloy consists of the (La, Mg)Ni3 phase and the LaNi5 phase. The maximum discharge capacity of the La0.7Mg0.3Ni2.875Co0.525Mn0.1alloy increases from 277.5mAh/g to 406.2mAh/g with increasing temperature from -20℃ to 30℃. Moreover, with increasing temperature, the discharge plateau potential is more negative, the discharge overpotential declines, and the polarization of the alloy electrode decreases. The high rate dischargeability, exchange current density and hydrogen diffusion coefficient of the alloy electrode all increase with increasing temperature, which indicates that the electrochemical kinetic property of the alloy electrode is improved. The activation energy for hydrogen diffusion in the alloy electrode is calculated to be 17.6kJ/mol.
Key words: hydrogen storage alloy; temperature characteristic; electrochemical properties; kinetics
