Horn-like Pore Entrance Boosts Charging Dynamics and Charge Storage of Nanoporous Supercapacitors

Abstract

Optimizing the synergy between nanoporous carbons and ionic liquids can significantly enhance the energy density of supercapacitors. The highest energy density has been obtained as the size of porous carbon matches the size of ionic liquids, while it may result in slower charging dynamics and thus reduce the power density. Enhancing energy storage without retarding charging dynamics remains challenging. Herein, we designed porous electrodes by introducing an optimized horn-like entrance to the nanopore, which can concurrently improve supercapacitors’ charging dynamics and energy storage. Our results revealed the mechanism of improved charging lies in the gradual desolvation process and optimized ion motion paths: the former expedites the adsorption of the counterion by reducing the transitional energy barrier for ions entering the pores, and the latter accelerates the co-ion desorption and eliminates ion overfilling. Meanwhile, the enhancement of energy density could be attributed to the multi-ion coordinated migration.