  The asymmetric behaviors of capacitance and dynamics features in the cathode
and anion are universal at porous supercapacitors. Understanding that is
important to design optimal supercapacitors. In this work, we performed
constant-potential molecular dynamics simulations to reveal asymmetric features
of porous supercapacitors and their effects on capacitance and charging
dynamics. Results revealed the capacitance and charging dynamics are correlated
strongly with asymmetric response of the cation and anion in cathode and anode,
and symmetrizing ion response could boost the charging dynamics.
Counterintuitively, the charging dynamics of negatively charged narrow pore is
slow, although its in-pore ions diffuse fast, which could be attributed to
longer and roundabout motion paths for co-ion desorption caused by ion
overfilling. Compared with the electrode with single size pore, the ion
overfilling also occurs in the electrode with multiple pore sizes, while co-ion
desorption is accelerated, associated with over-charging phenomenon, thus
enhancing the charging dynamics.
