Redox-active phthalocyanine-decorated graphene aerogels for high-performance supercapacitors based on ionic liquid electrolyte

Abstract

Ionic liquids (ILs) with a wide potential window have shown great potential in the fabrication of high-energy supercapacitors (SCs). However, developing pseudocapacitive material-matching IL electrolytes for further incorporating their energy-storing advantages is still a great challenge. Herein, we demonstrated the one-step hydrothermal synthesis of phthalocyanine (PC) and copper(II) phthalocyanine (CuPC)-functionalized reduced graphene oxide aerogels (PC-rGA and CuPC-rGA, respectively). PC and CuPC with a nitrogen-containing π-conjugated macrocyclic structure and redox activity were anchored on the surface of graphene sheets via π–π interactions, and thus PC-rGA and CuPC-rGA could match imidazolium IL electrolytes and provide pseudocapacitance, exhibiting an enhanced specific capacitance of 192 F g⁻¹ and 201 F g⁻¹ at 1 A g⁻¹, respectively. Moreover, the symmetric SCs assembled using the aerogels delivered a high energy density of 111 W h kg⁻¹ at a power density of 1009 W kg⁻¹ for CuPC-rGA, and 107 W h kg⁻¹ at 1000 W kg⁻¹ for PC-rGA.