硼添加对La-Mg-Ni-Co系贮氢电极合金的微结构及电化学性能的影响

Effects of Boron Addition on Structural and Electrochemical Properties of La-Mg-Ni-Co System Hydrogen Storage Electrode Alloys

摘要:

系统研究了贮氢电极合金La0.7Mg0.3Ni2.65Co0.75Mn0.1Al0.2Bx (x=0，0.02，0.04，0.08)的微结构与电化学性能。XRD结果显示，所有合金均由(La, Mg)Ni3相与LaNi5相组成，B含量的增加导致(La, Mg)Ni3相的丰度不断增加，相应地LaNi5相的丰度逐渐下降。此外，合金的晶格参数与晶胞体积均随B含量的增加而减小。电化学测试分析表明，B的添加可以显著改善合金电极的高倍率放电性能，当B含量为0.04时达到最佳。微量B的加入对合金的循环稳定性能与活化性能影响很小，但降低合金电极的最大放电容量。此外还采用线性极化与阳极极化对合金电极的动力学性能进行了进一步研究

Abstract:

The structural and electrochemical properties of La0.7Mg0.3Ni2.65Co0.75Mn0.1Al0.2Bx (x=0-0.08) hydrogen storage electrode alloys were investigated systematically. The results from XRD show that all of the alloys consist of a (La, Mg)Ni3 phase and a LaNi5 phase. With the increase of B content, the abundance of the (La, Mg)Ni3 phase increases, accordingly that of the LaNi5 phase decreases, and the cell volumes of the two phases decrease. Electrochemical studies indicate that B addition can effectively improve the high rate dischargeability (HRD) of the alloy electrode, and the optimal value of HRD1000 reaches 57.1% as x being 0.04. With the addition of small amount of B, the cycling stability and activation properties of the alloy electrodes keep almost unchanged, but the maximum discharge capacity (Cmax) decreases. In addition, the electrochemical kinetics investigations including the linear polarization and anodic polarization were also performed in detail