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.