Supercapacitors
are electrochemical devices which store energy
by ion adsorption on the surface of a porous carbon. They are characterized
by high power delivery. The use of nanoporous carbon to increase their
energy density should not hinder their fast charging. However, the
mechanisms for ion transport inside electrified nanopores remain largely
unknown. Here we show that the diffusion is characterized by a hierarchy
of time scales arising from ion confinement, solvation, and electrosorption
effects. By combining electrochemistry experiments with molecular
dynamics simulations, we determine the in-pore conductivities and
diffusion coefficients and their variations with the applied potential.
We show that the diffusion of the ions is slower by 1 order of magnitude
compared to the bulk electrolyte. The desolvation of the ions occurs
on much faster time scales than electrosorption.
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