High‐Voltage Stability of Ionic‐Liquid‐Based Electrochemical Double Layer Capacitors with a Bimodal Porous Carbon Electrode,ChemElectroChem

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High‐Voltage Stability of Ionic‐Liquid‐Based Electrochemical Double Layer Capacitors with a Bimodal Porous Carbon Electrode
ChemElectroChem ( IF 3.5 ) Pub Date : 2018-09-19 , DOI: 10.1002/celc.201801044
Amir Reza Aref ₁ , Ramakrishnan Rajagopalan _{2,

3} , Clive A. Randall _{3,

4}

Affiliation

Micropores (<2 nm) and small mesopores (width between 2 and 10 nm) in the structure of carbon play an important role in determining both the charge storage properties and voltage stability of ionic‐liquid‐based electrochemical double layer capacitors (EDLCs). We demonstrate that the use of bimodal porous carbon electrodes results in excellent voltage stability and good capacitance retention (>90 %), as determined by using voltage holding tests at 3.5 V over 250 h. Furthermore, a three‐electrode split cell study showed that the voltage stability in bimodal carbon was achieved because of more symmetric potential distribution and similar electrode capacitances between the positive and negative electrodes as compared to purely microporous carbon electrode. The presence of larger mesopores (5–10 nm) in the bimodal carbon facilitates the access and rearrangement of the bulkier cations at the electrode/electrolyte interface, whereas this is severely hindered in purely microporous carbon electrode. By using a lumped transmission line model, we delineated the contribution of both smaller and larger pores in the bimodal carbon towards the impedance performance of EDLCs.

中文翻译：

具有双峰多孔碳电极的基于离子液体的电化学双层电容器的高压稳定性

碳结构中的微孔（<2 nm）和小中孔（宽度在2到10 nm之间）在决定离子液体基电化学双层电容器（EDLC）的电荷存储性能和电压稳定性方面起着重要作用。我们证明使用双峰多孔碳电极可产生出色的电压稳定性和良好的电容保持率（> 90％），这是通过在250个小时内在3.5 V下进行电压保持测试确定的。此外，三电极分裂电池研究表明，与纯微孔碳电极相比，双峰碳具有更高的电压稳定性，这是因为正电极和负电极之间的电势分布更对称且电极电容相似。双峰碳中较大的中孔（5–10 nm）的存在有利于电极/电解质界面处较大阳离子的进入和重排，而在纯微孔碳电极中则严重受到阻碍。通过使用集总传输线模型，我们描述了双峰碳中较小和较大的孔对EDLC阻抗性能的贡献。

更新日期：2018-09-19

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