稀土组成对贮氢合金La0．8（1-x）Ce0．8x（PrNd）0．2B5性能的影响

Effect of Rare Earth Composition on the Properties of the Hydrogen Storage Alloys La0.8(1-x)Ce0.8x(PrNd)0.2B5

摘要:

系统研究了A侧稀土元素中Ce含量对AB5犁贮氢合金La0．8（1-x)Ce0．8x(PrNd)0．2B5的结构、热力学性能、电化学性能和动力学性能的影响。结果表明：Ce含量对合金的结构基本上没有明显的影响，合金的晶胞参数a、c及晶胞体积与Ce的含量的变化呈线性关系；随着Ce含量增加，合金的吸放氢平台压力升高，滞后效应减小，吸氢量减小，合金氢化物的热力学稳定性变差：Ce含量的变化对合金的电化学活化速度影响很小，但Ce含量的增加可以明显提高合金的放电中值电位，改善合金的高倍率、高功率放电性能和动力学性能。

Abstract:

The effects of the Ce content on the structure, thermodynamics, electrochemical properties and kinetic performance of the AB5-type hydrogen storage alloys La0.8(1-x)Ce0.8x(PrNd)0.2B5 have been systematically studied. The results show that, the Ce content dependence of the alloy structure is negligible, though the cell parameters a, c and the cell volume change linearly with Ce content. With the increase of the Ce content, the equilibrium pressure for hydrogen absorbing-desorbing of the alloys increases, the hysteresis gets smaller, and the thermodynamic stability of alloy hydride becomes poorer. The Ce content has a little effect on the electrochemical activation property of the alloys, its increase could raise the charge-discharge voltage plateau of the alloys, could improve the high-rate discharge ability and power characteristics of the alloys, while the discharge capacity at low discharge current is decreased. The increase of the Ce content is beneficial to improving kinetic performance of the alloys, it could decrease charge transfer resistance of the electrode reaction and make it more reversible. Hydrogen in the alloys diffuses faster with the increase of the Ce content.