Effect on the Pore-Size Dependence of an Organic Electrolyte Supercapacitor

Journal Article · Sun Jan 01 04:00:00 EST 2012 · Journal of Physical Chemistry Letters

DOI:https://doi.org/10.1021/jz3004624· OSTI ID:1049824

Jiang, Deen ^[1]; Jin, Zhehui ^[2]; Henderson, Douglous ^[3]; Wu, Jianzhong ^[2]

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1. ORNL
2. University of California, Riverside
3. Brigham Young University

Organic electrolytes such as tetraethylammonium tetrafluoroborate dissolved in acetonitrile (TEA-BF{sub 4}/ACN) are widely used in commercial supercapacitors and academic research, but conflicting experimental results have been reported regarding the dependence of surface-area-normalized capacitance on the pore size. Here we show from a classical density functional theory the dependence of capacitance on the pore size from 0.5 to 3.0 nm for a model TEA-BF{sub 4}/ACN electrolyte. We find that the capacitance-pore size curve becomes roughly flat after the first peak around the ion diameter, and the peak capacitance is not significantly higher than the large-pore average. We attribute the invariance of capacitance with the pore size to the formation of an electric double-layer structure that consists of counterions and highly organized solvent molecules. This work highlights the role of the solvent molecules in modulating the capacitance and reconciles apparently conflicting experimental reports.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1049824
• Journal Information: Journal of Physical Chemistry Letters, Journal Name: Journal of Physical Chemistry Letters Journal Issue: 13 Vol. 3; ISSN 1948-7185
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ACETONITRILE
CAPACITANCE
ELECTROLYTES
FUNCTIONALS
SOLVENTS