ABSTRACT

Cycling stability of electrodes is a key performance index that determines the working life of supercapacitors. However, unlike specific capacitance and coulombic efficiency, nearly all researches in the literature report the cycling performance of electrodes with only one cyclic voltammetry (CV) scan rate/galvanostatic charge/discharge (GCD) current density, which is highly likely to overestimate the cycling stability. In this work, we investigate the dependence of cycling stability on CV scan rate, with polyaniline electrodes as examples. Our systematic experimental measurements show that scan rate has a marked effect on capacitance retention of the electrodes. A low scan rate leads to unsatisfactory cycling performance, while a high scan rate gives excellent data. The results can be understood with the aid of scanning electron microscope images. It is recommended that cycling performance of the PANi electrodes should be tested at relatively low CV scan rate/GCD current density, so as not to report an overestimation.

摘要

电极的循环稳定性是决定超级电容器工作寿命的关键性能指标。然而，与比电容和库仑效率不同，几乎所有文献研究都报告了只有一种循环伏安法 (CV) 扫描速率/恒电流充电/放电 (GCD) 电流密度的电极的循环性能，这很可能高估了循环稳定。在这项工作中，我们以聚苯胺电极为例研究了循环稳定性对 CV 扫描速率的依赖性。我们的系统实验测量表明，扫描速率对电极的电容保持率有显着影响。低扫描速率会导致循环性能不令人满意，而高扫描速率会提供出色的数据。借助扫描电子显微镜图像可以理解结果。