Highly dispersed RuO2-biomass carbon composite made by immobilization of ruthenium and dissolution of coconut meat with octyl ammonium salicylate ionic liquid for high performance flexible supercapacitor

Poor dispersion of metal oxide-biomass carbon composite limits its further improvement in electrochemical properties. The study reports synthesis of highly dispersed RuO2-biomass carbon nanocomposite (HD-RuO2-BC). Octyl ammonium salicylate ionic liquid was combined with Ru3+ ion to form Ru-based ionic liquid. Followed by addition of coconut meat, microwave treatment to form homogeneous solution, thermal reduction in N2 and oxidation in air in sequence. The resulting HD-RuO2-BC shows three-dimensional architecture and high Ru loading of 9.2%. RuO2 nanoparticles of 6.2 nm were uniformly dispersed in biomass carbon sheets. Excellent dispersion and small size of RuO2 nanoparticles achieve to a significant synergy between RuO2 and biomass carbon. HD-RuO2-BC electrode gives high capacitance of 907.7 F g-1 at 1 A g-1. The value is more than that of BC (150.6 F g-1) and RuO2 electrodes (584.7 F g-1), verifying that introduction of RuO2 achieves to an obviously enhanced capacitance. The symmetrical flexible supercapacitor exhibits excellent supercapacitor performances, including high capacitance (403.8 F g-1 at 1.0 A g-1), rate-capacity (223.1 F g-1 at 50 A g-1), cycling stability (98.2% capacity retention after 10,000 cycles at 50 A g-1) and energy density (378.7 Wh Kg-1at power density of 5199.2 W kg-1).