固液空间比对粘结式Ni(OH)2电极放电行为的影响

采用恒电流充放电法、交流阻抗法、循环伏安法研究了固液空间比对粘结式Ni(OH)2电极放电行为的影响,通过扫描电镜(SEM)观察了电极的表面形貌.结果表明:在单位面积活性物质载量一定的条件下,电极较厚,则活性物质颗粒之间的间隙较多;随着固液空间比的不断下降,Warburg扩散区的扩散速度加快,但电极的充电效率降低,放电容量减少,活性物质利用率减小,电荷转移电阻增大,填充密度增大到一定程度时,液相传质已经不容忽略.

Effect of solid-to-liquid space ratio on discharging behavior of pasted Ni(OH)2 electrodes

The effect of solid-to-liquid space ratio on the discharging behavior of pasted Ni(OH)_2 electrodes were investigated by galvanostatic charge-discharge, electrochemical impedance spectroscopy, cyclic voltammetry. The morphologies of the electrodes were observed by SEM. The more clearances were found between the active material grains for the thicker electrodes when the active material loading per unit area was a constant. Experimental results show the faster diffusion rate at Warburg zero, but, lower charge efficiency, less discharge capacity, smaller active material utilization, larger charge transfer resistance with the decrease of the solid-to-liquid space ratio for the Ni(OH)_2 electrodes. The mass transfer of the solution phase could not be ignored when the active material loading density was increased to some extent.