Single-Layered Mesoporous Carbon Sandwiched Graphene Nanosheets for High Performance Ionic Liquid Supercapacitors

Abstract

Ionic liquid based supercapacitors generally using nanoporous carbon as electrode materials hold promise for future energy storage devices with improved energy density, but their power performances are limited by the high viscosity and relatively large size of ionic liquid electrolytes. Understanding the relationship between the pore size of nanoporous carbon, the ionic liquid electrolyte diffusivity, and the energy/power density is critical for the development of ionic liquid based supercapacitors with high performance. Herein, we report the synthesis of single-layered mesoporous carbon sandwiched graphene nanosheets (sMC@G) with mesopore-dominant (82% ∼89%) high surface area and tunable mesopore sizes (4.7, 6.8, 9.4, 10.6, and 13.9 nm). When using 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) as the electrolyte with a cation size of 0.76 nm, it is demonstrated that the ion diffusion coefficient increases a little when the mesopore size is not larger than 6.8 nm, and then jumps dramatically in ...