Stable RuO2-based ternary composite electrode of sandwiched framework for electrochemical capacitors

TiO2-doped RuO2 nanoparticles, obtained through wet milling and sol-gel process, are coated on thin SnO2 film covered tantalum substrate by magnetron sputtering to make a composite electrode of sandwiched framework. Phase structure, morphology, specific surface area, pore distribution as well as electrochemical performance of this composite electrode are tested and analyzed. Our results indicate that sample annealed at 260 °C for 4 h has optimal microstructure and electrochemical performance at doping level of 15 wt.% TiO2 with particles size of 38-43 nm and specific surface area of 22.330 m2 g−1. Specific capacitance of 692 Fg−1 (the highest in this study), good charge-discharge behavior, low equivalent series resistance as well as long cycling life are observed. Integrating into a 50 V 8000 μF electrochemical capacitor, specific energy and specific power reach 31.6 in Wh.Kg−1 and specific power of 2032 W Kg−1, respectively. Meanwhile, composite electrode shows stable capacitance without hydrogen evolution and peeling between TiO2-doped RuO2 nanoparticles and thin SnO2 film modified tantalum substrate.