LaNi_(2.5)Co_(0.5)储氢合金在充放电循环过程中的电化学性能研究

以感应熔炼法制备的LaNi_(2.5)Co_(0.5)合金为研究对象,对该合金及其氢化物的相结构进行了分析,并对合金电极的放电容量保持率、高倍率放电性能、氢扩散系数及极化电流密度等电化学性能进行了研究.结果表明:吸氢后的合金会产生明显的非晶化现象,造成合金吸放氢能力和氢化物稳定性下降.随着循环次数的增加,合金的放电容量和高倍率放电性能均表现出先快速下降到逐渐缓慢降低的趋势,而合金的氢扩散系数和极化电流密度却呈现出不同的变化趋势.高倍率放电性能的下降主要与合金表面反应活性相关,说明表面劣化现象是造成合金电化学性能衰退的主要因素.

Study on Electrochemical Performance of LaNi_(2.5)Co_(0.5) Hydrogen Storage Alloy during Charge and Discharge Cycles

The phase structures of LaNi_(2.5)Co_(0.5) alloy and its hydride which was prepared by induction melting methodwere analyzed,and the electrochemical properties such as discharge capacity retention,high rate discharge performance,hydrogen diffusion coefficient and polarization current of the alloy electrode were also investigated.The results showed that the amorphous phenomena occurred after charging for the alloy,which resulted in the decrease of hydrogen concentration and hydride stability.The discharge capacity and high rate of dischargeability of the alloy decreased first fast and then slowly by increasing cycles,but the hydrogen diffusion coefficient and polarization current density of the alloys showed different variation trend.The high rate dischargeability was mainly controlled by the surface reactivity,which indicated that the surface degradation was the main factor on electrochemical performances of the alloy electrode.