Cross-linked and pillared graphene with nonconventional redox benzidine dimethyl ether for high-performance supercapacitors

Abstract

To hinder Van der Waals-induced agglomeration between graphene sheets to increase specific surface area, and to supplement pseudocapacitance, graphene processing with active molecules is highly effective. Redox polymers and quinones, instead of aromatic ethers, were popular candidates. They were universally blended with graphene sheets through noncovalent modes, leading to issues of electrochemical stability and rate capability, etc. Herein, we broke through stereotype to develop aromatic ethers–benzidine with two remote methoxyls (i.e. 3,3′–dimethoxybenzidine, DMeOBD)–to covalently functionalize graphene, obtaining the cross-linked and pillared graphene electrode material (DMeOBD-rGO). It exhibited redox activity and featured a combination of electrochemical double layer supercapacitor and pseudocapacitor, thus yielded an enhanced specific capacitance of 363 F g−1. When assembled into two-electrode solid-state supercapacitors, the whole devices also delivered an impressive specific capacitance of 263 F g−1, and a high energy density of 13.2 Wh kg−1, along with excellent rate capability and cycling stability.