热处理对La_(0.7)Mg_(0.3)Ni_(2.8)Co_(0.5)贮氢合金电化学性能的影响  

Effects of Heat Treatment on Electrochemical Properties of La_(0.7)Mg_(0.3)Ni_(2.8)Co_(0.5) Hydrogen Storage Alloy

作　　者：刘永锋[1] 金勤伟[1] 高明霞[1] 朱云峰[1] 张志鸿[1] 潘洪革[1] 

机构地区：[1]浙江大学,浙江杭州310027

出　　处：《稀有金属材料与工程》2003年第11期942-945,共4页Rare Metal Materials and Engineering

基　　金：国家自然科学基金重点项目资助(50131040)

摘　　要：La0.7Mg0.3Ni2.8Co0.5贮氢电极合金经过适当热处理后(1123K),最大放电容量、循环稳定性、高倍率放电性能(HRD)、交换电流密度(I0)以及极限电流密度(IL)都有明显改善,铸态合金电极的最大放电容量为392mAh/g,放电电流密度Id=2000mA/g时,HRD2000=74.0%,I0=266.7mA/g,IL=3425.5mA/g;经1123K保温8h退火的合金电极的最大放电容量提高到414mAh/g,HRD2000=76.2%,I0=407.9mA/g,IL=3753.6mA/g。X射线衍射(XRD)分析表明,衍射峰宽度随着退火温度的升高而变窄,其原因是合金经退火处理相结构的变化和成分的均匀化。The effects of heat treatment on the electrochemical properties and structure of La0.7Mg0.3Ni2.8Co0.5 hydrogen storage alloy were studied. It is found, by electrochemical studies, that the discharge capacity, cycle stability, high rate dischargeability (HRD), exchange cur-rent density I-0 and the limiting current density I-L of the alloy electrodes increase after annealing treatment. The discharge capacity of the alloy annealed at 1 123 K and the cycle life of the alloy annealed at 1 223 K are the highest and the best, respectively. In addition, the exchange current density I-0 and the limiting current density IL of the alloy electrode increase with annealing at 1 123 K and then decrease with increasing annealing temperature. Meanwhile, the improvement of the high rate dischargeability (HRD) of the annealing samples is consistent with the variation of the exchange current density I-0 and the limiting current density IL. Furthermore, it is found, by XRD analysis, that the peak positions and peak intensities change with increasing annealing temperature, which can be ascribed to the structural change and more homogeneous composition after annealing treatment.

关 键 词：热处理 La0.7Mg0.3Ni2.8Co0.5 贮氢合金 电化学特性 

分 类 号：TG139.7[一般工业技术—材料科学与工程] TG166[金属学及工艺—合金]