Microstructure and electrochemical properties of LaNi_(4-x)FeMn_x (x=0-0.8) hydrogen storage alloys
来源期刊：JOURNAL OF RARE EARTHS2009年第5期
论文作者：TAO Mingda CHEN Yungui YANG Heng WU Chaoling
Key words：hydrogen storage materials; electrochemical properties; Co-free AB5-type alloy; rare earths;
Abstract: In order to reduce the cost of LaNi5 based hydrogen storage alloys, effect of substitution of Mn for Ni on structural and electro-chemical properties of LaNi_(4-x)FeMn_x(x=0-0.8) hydrogen storage alloys was studied systematically. X-ray diffraction (XRD) and scanning electron microscope (SEM) showed that LaNi5 and La_2Ni_7 phases were invariably present in all alloy samples, and when x≥0.4, (Fe,Ni) phase was observed. Electrochemical studies revealed that the discharge capacity reached a maximum value of 306.4 mAh/g when x=0.2 and the cycling stability decreased with the increase of x.With the increase of Mn content, hydrogen diffusion coefficient decreased, whereas high rate discharge-ability (HRD) and exchange current density first increased slowly when x≤0.2 and then decreased markedly when x=0.8,indicating that electrochemical reaction on the surface of alloy electrodes had strong influence on kinetic property.
TAO Mingda1，CHEN Yungui1，YANG Heng1，WU Chaoling1
(1.College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China)
Abstract:In order to reduce the cost of LaNi5 based hydrogen storage alloys, effect of substitution of Mn for Ni on structural and electro-chemical properties of LaNi_(4-x)FeMn_x(x=0-0.8) hydrogen storage alloys was studied systematically. X-ray diffraction (XRD) and scanning electron microscope (SEM) showed that LaNi5 and La_2Ni_7 phases were invariably present in all alloy samples, and when x≥0.4, (Fe,Ni) phase was observed. Electrochemical studies revealed that the discharge capacity reached a maximum value of 306.4 mAh/g when x=0.2 and the cycling stability decreased with the increase of x.With the increase of Mn content, hydrogen diffusion coefficient decreased, whereas high rate discharge-ability (HRD) and exchange current density first increased slowly when x≤0.2 and then decreased markedly when x=0.8,indicating that electrochemical reaction on the surface of alloy electrodes had strong influence on kinetic property.
Key words:hydrogen storage materials; electrochemical properties; Co-free AB5-type alloy; rare earths;
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