Self-assembled RuO2 nanoneedles on Ta/Cu foil for a robust and high-performance supercapacitor electrode

Abstract

High-density self-assembled RuO2 nanoneedles (NNs) are successfully fabricated on a tantalum (Ta)-coated copper (Cu) substrate via a mild hydrothermal reaction for an electrochemical supercapacitor electrode with a superior energy storage capacity and excellent electrochemical stability. The electrochemical properties of the RuO2 NNs based electrode in a diluted H2SO4 electrolyte are investigated. The extremely thin Ta insertion layer enhances the adhesion between the RuO2 NNs and the copper foil charge collector, thereby significantly enhancing the mechanical and electrochemical energy storage characteristics of the RuO2 NNs electrode. The proposed electrode exhibits a remarkable capacitive storage performance of 1420 F g−1 at a scan rate of 5 mV s−1 and excellent long-term cycling stability (∼ 98% of capacitance is retained at 100 mV s−1 after several hundred cycles). Moreover, the electrode shows a high energy density of ∼ 13 Wh kg−1 at a power density of 27 kW kg−1. The proposed strategy can facilitate the design of binder-free robust nanostructured oxide/hydroxide electrodes and can be extended to prepare high-performance catalysts and battery anodes.