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Capacitance dependence on the pore size of an organic electrolyte supercapacitor

ORNL Image
The capacitance of an organic-electrolyte supercapacitor inside a nanoslit shows a peak for the pore size around the ion-diameter, but becomes roughly flat beyond twice the ion diameter. This invariance is due to an electric double layer insensitive to the pore size. Inset shows the distribution of the anions and solvent dipoles (arrows) inside positively charged slit walls.

For the first time, the pore size dependence of the capacitance of an organic-electrolyte supercapacitor and the underlying electric double layer structure has been rationalized by classical density functional theory (CDFT)

Significance and Impact:

This new understanding reconciles previous conflicting experimental reports, and seeks further experiments to characterize the predicted structure of the electric double layer which suggests alignment of the polar solvents

Research Details:

  • CDFT calculations showed the capacitance dependence on the pore size from 0.5 to 3.0 nm for an organic electrolyte, bridging the micro- to the mesopore
  • The capacitance shows a clear peak around the ion diameter and insensitivity beyond ~1.0 nm.

For more information, please contact David Wesolowski, [email protected].