Hierarchical Micro‐ and Mesoporous Carbide‐Derived Carbon as a High‐Performance Electrode Material in Supercapacitors

Abstract

Ordered mesoporous carbide‐derived carbon (OM‐CDC) materials produced by nanocasting of ordered mesoporous silica templates are characterized by a bimodal pore size distribution with a high ratio of micropores. The micropores result in outstanding adsorption capacities and the well‐defined mesopores facilitate enhanced kinetics in adsorption processes. Here, for the first time, a systematic study is presented, in which the effects of synthesis temperature on the electrochemical performance of these materials in supercapacitors based on a 1 M aqueous solution of sulfuric acid and 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ionic liquid are reported. Cyclic voltammetry shows the specific capacitance of the OM‐CDC materials exceeds 200 F g−1 in the aqueous electrolyte and 185 F g−1 in the ionic liquid, when measured in a symmetric configuration in voltage ranges of up to 0.6 and 2 V, respectively. The ordered mesoporous channels in the produced OM‐CDC materials serve as ion‐highways and allow for very fast ionic transport into the bulk of the OM‐CDC particles. At room temperature the enhanced ion transport leads to 75% and 90% of the capacitance retention at current densities in excess of ∼10 A g−1 in ionic liquid and aqueous electrolytes, respectively. The supercapacitors based on 250–300 μm OM‐CDC electrodes demonstrate an operating frequency of up to 7 Hz in aqueous electrolyte. The combination of high specific capacitance and outstanding rate capabilities of the OM‐CDC materials is unmatched by state‐of‐the art activated carbons and strictly microporous CDC materials.