Abstract
Supercapacitors composed of slit-shaped micropores ranging in size from
0.67 to 1.8 nm in a room-temperature ionic liquid were studied to investigate the
dependence of capacitance (C) on the pore size (d) using molecular dynamics
simulations. The capacitance versus pore size (i.e., the Cd curve) was found to
exhibit two peaks located at 0.7 and 1.4 nm, respectively. Specifically, as the pore shrinks
from 1.0 to 0.7 nm, the capacitance of the micropore increases anomalously, in good
agreement with experimental observations. We report herein that the second peak
within 1.0 to 1.8 nm is a new feature of the Cd curve. Furthermore, by analogy to the
wave interference, we demonstrate that the interference of two electrical double layers
near each slit wall does not only explain the entire Cd curve, including the anomalous
character, but also predicts the oscillatory behavior of Cd curve beyond 1.8 nm.