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Volume 199, 2017
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Underscreening in concentrated electrolytes

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Abstract

Screening of a surface charge by an electrolyte and the resulting interaction energy between charged objects is of fundamental importance in scenarios from bio-molecular interactions to energy storage. The conventional wisdom is that the interaction energy decays exponentially with object separation and the decay length is a decreasing function of ion concentration; the interaction is thus negligible in a concentrated electrolyte. Contrary to this conventional wisdom, we have shown by surface force measurements that the decay length is an increasing function of ion concentration and Bjerrum length for concentrated electrolytes. In this paper we report surface force measurements to test directly the scaling of the screening length with Bjerrum length. Furthermore, we identify a relationship between the concentration dependence of this screening length and empirical measurements of activity coefficient and differential capacitance. The dependence of the screening length on the ion concentration and the Bjerrum length can be explained by a simple scaling conjecture based on the physical intuition that solvent molecules, rather than ions, are charge carriers in a concentrated electrolyte.

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Publication details

The article was received on 05 Dec 2016, accepted on 27 Jan 2017 and first published on 27 Jan 2017


Article type: Paper
DOI: 10.1039/C6FD00250A
Citation: Faraday Discuss., 2017,199, 239-259
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    Underscreening in concentrated electrolytes

    A. A. Lee, C. S. Perez-Martinez, A. M. Smith and S. Perkin, Faraday Discuss., 2017, 199, 239
    DOI: 10.1039/C6FD00250A

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