Free-Standing rGO-CNT Nanocomposites with Excellent Rate Capability and Cycling Stability for Na2SO4 Aqueous Electrolyte Supercapacitors

Facing the increasing demand for various renewable energy storage devices and wearable and portable energy storage systems, the research on electrode materials with low costs and high energy densities has attracted great attention. Herein, free-standing rGO-CNT nanocomposites have been successfully synthesized by a facile hydrothermal method, in which the hierarchical porous network nanostructure is synergistically assembled by rGO nanosheets and CNT with interlaced network distribution. The rGO-CNT composite electrodes with synergistic enhancement of rGO and CNT exhibit high specific capacitance, excellent rate capability, exceptional conductivity and outstanding long-term cycling stability, especially for the optimal rGO-CNT30 electrode. Applied to a symmetric supercapacitor systems (SSS) assembled with an rGO-CNT30 electrode and with 1 M Na2SO4 aqueous solution as the electrolyte, the SSS possesses a high energy density of 12.29 W h kg(-1) and an outstanding cycling stability, with 91.42% of initial specific capacitance after 18,000 cycles. Results from these electrochemical properties suggest that the rGO-CNT30 nanocomposite electrode is a promising candidate for the development of flexible and lightweight high-performance supercapacitors.