摘要
La0.7Mg0.3Ni3.4-xCo0.6Mnx(x=0.0-0.5)合金主要由(La,Mg)Ni3相和LaNi5相构成,各相的晶胞参数和晶胞体积均随Mn含最的增加而增大。随Mn含量的增加,合金的放氢平衡压力从0.128MPa(x=0.0)下降到0.067MPa(x=0.5),导致最大吸氢量从x=0.0时的1.19%(质量分数,下同)逐渐增加到x=0.4时的1.38%。合金的最大放电容量随Mn含量的增加首先从330.4mAh/g(x=0.0)增加到360.6mAh/g(x=0.4),然后减小到346.9mAh/g(x=0.5)。随Mn替代量的增加,合金电极的高倍率放电能力先改善后降低,合金电极的表面反应阻抗先降低后升高,而氢的扩散系数先增加后减小,说明合金的电化学动力学性能首先提高然后降低。
La0.7Mg0.3Ni3.4-xCo0.6Mnx (x=0.0-0.5) hydrogen storage alloys are mainly consisted of the (La, Mg)Ni3 phase and the LaNi5 phase. The lattice parameters and cell volumes of the component phases increase with increasing Mn content. P-C-T curves show that the equilibrium pressure for hydrogen desorption decreases from 1.28 atm (x=0.0) to 0.67 atm (x=0.5) with increasing x, and the hydrogen storage capacity increases from 1.19 wt% (x=0.0) to 1.38 wt% (x=0.4). The electrochemical studies show that the maximum discharge capacity increases first from 330.4 mAh/g to 360.0 mAh/g with increasing x from 0.0 to 0.4, and then decreases to 346.9 mAh/g when for x of 0.5. The HRD and the hydrogen diffusion coefficient D of the alloy electrodes increases firstly, then decrease with increasing Mn content, but the charge-transfer reaction resistant Rct decreases firstly, then increases. They imply that the electrochemical kinetics property of the La0.7Mg0.3Ni3.4-xCo0.6Mnx hydrogen storage alloys increases firstly and then decreases with increasing x from 0.0 to 0.5.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2005年第6期867-871,共5页
Rare Metal Materials and Engineering
基金
国家自然科学基金重点项目(50131040)资助
关键词
贮氢合金
元素替代
结构特性
P-C-T曲线
电化学性能
hydrogen storage alloy
element substitution
structure characteristics
P-C-T curves
electrochemical properties
