Ultrathin microporous carbon/few-layer graphene heterostructure for supercapacitor application

Abstract

The heterostructure consisting of ultrathin microporous carbon and graphene can exhibit many interesting properties benefiting from their unique physicochemical structure, and thus possess a great potential application in electrochemical energy storage devices. Herein, we report a novel catalysis strategy to construct nanometer-thick microporous carbon/few-layer graphene (FLG) heterostructure in the tens-of-nanometer-thick shells of hollow carbon spheres (HCSs). The thickness of microporous carbon in heterostructure can be reduced by intercalating more FLG sheets. Nano-sized thickness increases exposure ratio of micropores and shortens ion transport distance besides good conductivity of FLG sheets. The meso- and macropores in heterostructure further improves ion adsorption of high-density open micropores. The obtained ultrathin microporous carbon/FLG heterostructure shows high special capacitance (Cs) of 187 F·g−1 at 5.0 mV·s−1 and excellent rate capability. Furthermore, the loading of heterostructure electrode increases by 15 times, the Cs is up to 192 F·g−1 at 5.0 mV·s−1 with more excellent rate performance and robust long-term charge-discharge recyclability. After the loading mass increased by 29 times (2.85 mg·cm−2), the electrochemical performance still remains stable, indicating a great potential for supercapacitor application. The mechanism behind these phenomena was studied.