Theoretical Model for Nanoporous Carbon Supercapacitors

Journal Article · Tue Jan 01 04:00:00 EST 2008 · Angewandte Chemie International Edition

OSTI ID:951284

Sumpter, Bobby G ^[1]; Meunier, Vincent ^[1]; Huang, Jingsong ^[1]

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1. ORNL

The unprecedented anomalous increase in capacitance of nanoporous carbon supercapacitors at pore sizes smaller than 1 nm [Science 2006, 313, 1760.] challenges the long-held presumption that pores smaller than the size of solvated electrolyte ions do not contribute to energy storage. We propose a heuristic model to replace the commonly used model for an electric double-layer capacitor (EDLC) on the basis of an electric double-cylinder capacitor (EDCC) for mesopores (2 {50 nm pore size), which becomes an electric wire-in-cylinder capacitor (EWCC) for micropores (< 2 nm pore size). Our analysis of the available experimental data in the micropore regime is confirmed by 1st principles density functional theory calculations and reveals significant curvature effects for carbon capacitance. The EDCC (and/or EWCC) model allows the supercapacitor properties to be correlated with pore size, specific surface area, Debye length, electrolyte concentration and dielectric constant, and solute ion size. The new model not only explains the experimental data, but also offers a practical direction for the optimization of the properties of carbon supercapacitors through experiments.

• Research Organization: Oak Ridge National Laboratory (ORNL); Center for Nanophase Materials Sciences; Center for Computational Sciences
• Sponsoring Organization: ORNL LDRD Director's R&D
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 951284
• Journal Information: Angewandte Chemie International Edition, Journal Name: Angewandte Chemie International Edition Journal Issue: 3 Vol. 47; ISSN 0570-0833
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
36 MATERIALS SCIENCE
CAPACITORS
CARBON
DEBYE LENGTH
DENSITY FUNCTIONAL METHOD
MATHEMATICAL MODELS
NANOSTRUCTURES
PERMITTIVITY
PORE STRUCTURE
SPECIFIC SURFACE AREA