非化学计量比贮氢电极合金的电化学性能和结构及热力学研究  

Electrochemical Properties and Structural Analysis of Non-Stoichiometric Hydrogen Storage Alloys

作　　者：江建军[1] 雷永泉[2] 孙大林[2] 吴京[2] 王启东[2] 

机构地区：[1]华中理工大学 [2]浙江大学

出　　处：《稀有金属材料与工程》1997年第3期14-19,共6页Rare Metal Materials and Engineering

基　　金：国家"863"高技术资助

摘　　要：在分别优化稀土Ａ组元和过渡族Ｂ组元基础上，研究了ＡＢγ合金中化学计量比γ值对其电化学性能的影响。结果表明，超化学计量比（γ＝５．３）的合金具有较高的放电容量（２９５ｍＡ·ｈ／ｇ）和较小的循环容量衰退（电化学容量在２５０次循环后为８３．６％），但其大电流放电能力有所降低。经ＸＲＤ分析，γ＝５．３的合金具有最大的晶胞体积。从放电容量和循环寿命来看，超化学计量比合金优于化学计量比合金和欠化学计量比合金，但其高倍率放电能力有所降低。用Ｓｉｅｖｅｒｔ固——气吸放氢（ｐ－Ｃ－Ｔ）法求得吸放氢反应的ΔＨ和ΔＳ表明，超化学计量比合金ＡＢ５．３的生成热较负，形成的氢化物比较稳定，氢原子扩散困难，且使氢原子发生电化学氧化反应阻力增大，因而使电极合金的大电流放电能力降低。The effects of stoichiometric ratio (r value) on the properties of AB γ -type hydrogen-storage alloys have been studied The results show that the discharge capacity and capacity persistence after 250 cycles are 295 mA·h/g and 83 6% respectively, for the hyper-stoichiometric (γ=5 3) alloy, although its high-rate-discharge ability is lower than that of stoichometric alloy (γ=5) The higher capacity is due to the larger unit cell volume of the alloy with γ=5 3, as determined by X-ray diffraction analysis The thermodynamic functions Δ H and Δ S of the alloys were determined by the Sievert Methods through the P-C-T curve For the hyperstoichiometric(γ=5 3) alloy They are more negative value than for the stoichiometric alloy(γ=5) The high-rate-discharge ability of the hyper-stoichiometric alloy is lower than that of the stoichiometric alloy

关 键 词：贮氢合金 化学计量比 电极 电化学性能 热力学 

分 类 号：TG139.7[一般工业技术—材料科学与工程]