Confinement, Desolvation, And Electrosorption Effects on the Diffusion of Ions in Nanoporous Carbon Electrodes

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• 作者：Clarisse Pean ; Barbara Daffos ; Benjamin Rotenberg ; Pierre Levitz ; Matthieu Haefele ; Pierre-Louis Taberna ; Patrice Simon ; Mathieu Salanne
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：October 7, 2015
• 年：2015
• 卷：137
• 期：39
• 页码：12627-12632
• 全文大小：456K
• ISSN：1520-5126

文摘

Supercapacitors are electrochemical devices which store energy by ion adsorption on the surface of a porous carbon. They are characterized by high power delivery. The use of nanoporous carbon to increase their energy density should not hinder their fast charging. However, the mechanisms for ion transport inside electrified nanopores remain largely unknown. Here we show that the diffusion is characterized by a hierarchy of time scales arising from ion confinement, solvation, and electrosorption effects. By combining electrochemistry experiments with molecular dynamics simulations, we determine the in-pore conductivities and diffusion coefficients and their variations with the applied potential. We show that the diffusion of the ions is slower by 1 order of magnitude compared to the bulk electrolyte. The desolvation of the ions occurs on much faster time scales than electrosorption.