High-performance asymmetric supercapacitors using holey graphene electrodes and redox electrolytes

Construction of asymmetric supercapacitors with high energy and power densities using the same anode and cathode electrodes remains a great challenge. Herein, holey reduced graphene oxide (rGO) films are synthesized using a catalytic etching process and utilized as both cathode and anode electrodes for the supercapacitor construction. On the anode of an asymmetric supercapacitor, an electrical double layer capacitor is formed in 1M Na2SO4, while on the cathode a pseudocapacitor is fabricated where redox electrolytes of [Fe(CN)(6)](3-/4-) are added. The performance of as-formed asymmetric supercapacitors is varied with the pore sizes and densities on the holey rGO films. With a cell voltage of 2.0 V, a specific capacitance of as high as 101.25 F g(-1), an energy density of 56.25Wh kg(-1), a power density of 35.83kW kg(-1), and excellent long cycle life (98% of its specific capacitance even at 5000 charge/discharge cycles) are achieved. Such performance is superior to most of graphene based supercapacitors. Therefore, these asymmetric supercapacitors are promising for applications of storage systems with double-high densities. (C) 2019 Elsevier Ltd. All rights reserved.