Abstract
Using molecular dynamics simulations, we show that charge storage in subnanometer pores follows a distinct voltage-dependent behavior. Specifically, at lower voltages, charge storage is achieved by swapping co-ions in the pore with counterions in the bulk electrolyte. As voltage increases, further charge storage is due mainly to the removal of co-ions from the pore, leading to a capacitance increase. The capacitance eventually reaches a maximum when all co-ions are expelled from the pore. At even higher electrode voltages, additional charge storage is realized by counterion insertion into the pore, accompanied by a reduction of capacitance. The molecular mechanisms of these observations are elucidated and provide useful insight for optimizing energy storage based on supercapacitors.
Original language | English |
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Pages (from-to) | 1732-1737 |
Number of pages | 6 |
Journal | Journal of Physical Chemistry Letters |
Volume | 3 |
Issue number | 13 |
DOIs | |
State | Published - Jul 5 2012 |