Department of Chemistry, Faculty of Natural Sciences, Imperial College London, SW7 2AZ, UK.
J Phys Condens Matter. 2011 Jan 19;23(2):022201. doi: 10.1088/0953-8984/23/2/022201. Epub 2010 Dec 9.
In recent experiments (Chmiola et al 2006 Science 313 1760; Largeot et al 2008 J. Am. Chem. Soc. 130 2730) an anomalous increase of the capacitance with a decrease of the pore size of a carbon-based porous electric double-layer capacitor has been observed. We explain this effect by image forces which exponentially screen out the electrostatic interactions of ions in the interior of a pore. Packing of ions of the same sign becomes easier and is mainly limited by steric interactions. We call this state 'superionic' and suggest a simple model to describe it. The model reveals the possibility of a voltage-induced first order transition between a cation(anion)-deficient phase and a cation(anion)-rich phase which manifests itself in a jump of capacitance as a function of voltage.
在最近的实验中（Chmiola 等人，2006 年，《科学》313 卷 1760 页；Largeot 等人，2008 年，《美国化学会志》130 卷 2730 页），观察到一种反常的现象，即在基于碳的多孔电双层电容器中，随着孔径的减小，电容会异常增加。我们通过电象力解释了这一现象，电象力呈指数衰减，从而屏蔽了离子在孔内的静电相互作用。同种电荷的离子的堆积变得更容易，主要受到空间位阻的限制。我们称这种状态为“超离子态”，并提出了一个简单的模型来描述它。该模型揭示了在电压诱导下，阳离子（阴离子）缺乏相与阳离子（阴离子）富相之间可能发生一级相变的可能性，这种相变表现为电容随电压的跳跃。
