Surface Wettability Effect on Energy Density and Power Density of Supercapacitors

Many attempts have been made to improve the energy density of supercapacitors toward their large-scale applications in storing renewable energy. Herein, the surface wettability effect is unraveled with the combination of static and dynamic density functional theories through which the energy densities and power densities of electrochemical supercapacitors are analyzed with different sets of pore sizes, surface voltages, and bulk ion concentrations. We demonstrate that tuning the surface wettability of electrodes may improve the energy density but simultaneously reduce the power density, and an optimal energy density with a relatively small cost of power density can be achieved by adopting highly confined pores. In addition, increasing ion bulk concentration and/or surface voltage can enhance both the energy density and power density. This work provides a complementary dynamic insight into the surface wettability effect on the performance of supercapacitors.