Self-discharge in Manganese Oxide Electrochemical Capacitor Electrodes in Aqueous Electrolytes with Comparisons to Faradaic and Charge Redistribution Models
Self-discharge in Manganese Oxide Electrochemical Capacitor Electrodes in Aqueous Electrolytes with Comparisons to Faradaic and Charge Redistribution Models
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DOI：
10.1016/j.electacta.2014.03.104
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发表时间：
2014-09-10
影响因子：
6.6
通讯作者：
Oickle, Alicia A.
中科院分区：
文献类型：
--
作者：
Andreas, Heather A.;Black, Jennifer M.;Oickle, Alicia A.
测试了氧化锰薄膜的自放电曲线，以确定这些伪电容薄膜的自放电过程。将轮廓形状与四种自放电模型进行了比较：仅受活化控制的法拉第反应；仅限于电阻的电荷再分配；仅限于扩散的电荷再分配；或仅受活化控制的法拉第反应与电荷再分配的耦合。硬件电路模型(例如传输线)被用来模拟激活控制的反应和电阻受限的电荷再分布。Ru_2O_3被用作扩散限制电荷再分配的实验模型，而经历表面氧化的高孔炭则模拟了活化受控的法拉第反应和电荷再分配。氧化锰自放电与这些模型的比较表明，氧化锰表面发生了激活控制的法拉第反应，塔菲尔斜率为67+/-5 mV。此外，首次在这些薄膜中发现了电荷再分布的存在。在自放电过程中，激活受控的反应会将氧化锰表面放电，从而在表面和本体之间建立电位差--在表面电位较低的地方。这种电位差的结果是，在电荷再分配过程中，块状氧化锰为表面提供电荷，有效地减缓了自放电。(C)2014爱思唯尔有限公司。保留所有权利。
The self-discharge profiles of manganese oxide films were examined to identify the self-discharge processes for these pseudocapacitive films. The profile shape was compared to four self-discharge models: an activation-controlled Faradaic reaction only; resistance-limited charge redistribution only; diffusion-limited charge redistribution only; or an activation-controlled Faradaic reaction coupled with charge redistribution. Hardware circuitry models (e.g. a transmission line) were used to model the activation-controlled reaction and resistance-limited charge redistribution. Ruthenium oxide was used as an experimental model for diffusion-limited charge redistribution, while highly porous carbon undergoing surface oxidation modelled the activation-controlled Faradaic reaction coupled with charge redistribution. Comparison of the manganese oxide self-discharge to these models showed an, as yet unidentified, activation-controlled Faradaic reaction on the manganese oxide surface, with a Tafel slope of 67 +/- 5 mV. Additionally, the presence of charge redistribution was indicated in these films for the first time. During self-discharge, the activation-controlled reaction discharges the manganese oxide surface, setting up a potential differential between the surface and the bulk - where the surface has a lower potential. The result of this potential differential is that during charge redistribution the bulk manganese oxide provides charge to the surface, effectively slowing self-discharge. (C) 2014 Elsevier Ltd. All rights reserved.