活性碳堆积密度对双电层超级电容器性能的影响

Stacking density of active carbon and its impact on edlc capacity behavior

极片活性物质堆积密度对于超级电容器初期的活化过程极为重要,研究了极片辊压过程中堆积密度对电容性能的影响,测量了扣式超级电容器充放电5 000次循环的比电容、充放电特性曲线、放电中压和电化学阻抗谱。结果表明:比电容随极片活性碳的堆积密度提高而先升高后降低,扫描电镜结果表明较高的极片堆积密度可以压缩活性物质层的堆积孔,阻抗实验结果表明较高的极片堆积密度可以促使导电剂形成更有效的导电网络,从而降低极片内阻。但是,过高堆积密度反而会增大离子的传导阻力而增大内阻,导致比电容降低,优化的堆积密度为529×10^(–3)g/cm^3。

The stacking density of active material is very important to the super capacitor cycle.The effects of stacking density of sheet during rolling process on capacity behavior were researched through the measurement of the specific capacitance,the charge and discharge characteristic curves,half discharge voltage and electrochemical impedance spectroscopy during the5000cycles.The results show that the specific capacitance of active carbon electrode increases firstly and then decreases with bulk density increasing.The SEM results show that the high density compresses the large stacking hole of active material layer.Electrochemical impedance tests show that higher conductive agent promotes the formation of conductive network more effectively,thereby reducing the sheet resistance.However,higher stacking density would increase the ion diffusion resistance,which increase the cell resistance,resulting in reduced capacitance.The optimization of the bulk density is529×10–3g/cm3.