LAUSR

Self-discharge effects on the performance of an asymmetric electrochemical capacitors (ECs) was studied by incorporating a combination of different applicable self-discharge mechanisms into the capacitors mass transfer and charge conservation equations during charging and discharging. Key self-discharge parameters are the concentration of impurity ions and oxidized species, and the separator and the total thickness of the anode. The storable and deliverable energies of ECs with self-discharge were higher than those of a similar device without self-discharge and redox electrolyte when an insoluble redox product was used and the key self-discharge parameters were tuned. When the asymmetric ECs were charged and discharged rapidly, the rate of self-discharge was reduced, compared with when they were charged and discharged slowly. The shuttle self-discharge contributed the majority of the self-discharges in the asymmetric ECs. The charging and discharging time of the ECs was significantly dependent on the self-discharge rate, and this model gives a more practical evaluation of potential/energy decay exhibited during self-discharge. A theoretical explanation for a unique redox electrolyte that is convertible into insoluble species during the device charging to suppress self-discharge, as reported in the literature, was obtained.