Bendable RuO2/graphene thin film for fully flexible supercapacitor electrodes with superior stability

Ruthenium oxide (RuO2) is fabricated on graphene (Gr)-coated Copper (Cu) foil by using a cathodic electroplating technique for flexible supercapacitor electrode applications. The electrochemical properties of the RuO2/Gr/Cu electrode are investigated with a conventional three electrode configuration in 0.5 M H2SO4 electrolyte. The graphene insertion layer plays a key role in improving the structural and electrochemical properties of the RuO2 electrode film under the bent condition. The electrode exhibits a specific capacitance of 1561 F g−1 (0.015 F cm−1) at a scan rate of 5 mV s−1 and a significantly improved retention of 98% under the bent condition. The flexible RuO2/Gr/Cu electrode exhibits a high energy density of ∼13 Wh kg−1 at a power density of ∼21 kW kg−1. The excellent capacitance retention and electrochemical stability of the flexible RuO2/Gr/Cu electrode are due to the improved mechanical adhesion between the RuO2 and the current collector. This flexible RuO2/Gr/Cu film could be used as a supercapacitor electrode with a high capacity and long-cycle life for the next-generation flexible electronic applications.