为了改善La-Mg-Ni基贮氢合金的循环稳定性和综合电化学性能, 研究了电镀镍-钴合金对La0.88Mg0.12Ni2.95Mn0.10Co0.55Al0.10贮氢合金粉末表面形貌和电极电化学性能的影响. FESEM表明, 电镀处理后合金粉末表面沉积了球状的镍-钴合金颗粒. 电化学性能测试表明, 贮氢合金电极的放电容量、高倍率放电性能和循环稳定性均得到了显著改善. 200周循环时合金电极的容量保持率从未处理合金电极的60%提高到镀覆镍-钴合金的80%, 在放电电流密度1080mA/g下的高倍率放电性能提高了23%. 线性极化曲线和电化学阻抗分析结果显示, 包覆镍-钴合金后贮氢合金电极表面的电荷转移速率加快, 电催化活性提高.
丁慧玲1
,
2
,
蒿建生1
,
3
,
朱惜林2
,
3
,
李 媛2
,
韩树民1
,
2
,
张静武1
. 电镀镍-钴合金对La-Mg-Ni基贮氢合金电化学性能的影响[J]. 无机材料学报, 2010
, 25(6)
: 647
-652
.
DOI: 10.3724/SP.J.1077.2010.00647
In order to improve cycling stability and overall electrochemical properties of La-Mg-Ni-based hydrogen storage alloys, an electroplating treatment was applied on La0.88Mg0.12Ni2.95Mn0.10Co0.55Al0.10 alloy powders. The effect of cobalt-nickel coating on the morphological and electrochemical properties was studied. FESEM results show that spherical nickel-cobalt alloy particles are deposited on the surface of the alloys. Electrochemical tests indicate that the maximum discharge capacity, the cycling stability and the high rate dischargeability (HRD) are remarkably improved. After 200 charge/discharge cycles, the capacity retention rate increases from 60% (uncoated) to 80% (nickel-cobalt coated). The HRD at 1080mA/g rises by 23% for the nickel-cobalt coated alloy electrodes. Linear polarization and Electrochemical Impedance Spectroscope (EIS) results reveal that the surface of alloy electrodes with cobalt-nickel coatings is more catalytic for the electrochemical charge transfer reactions.
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