Anchoring Hydrous RuO2 on Graphene Sheets for High-Performance Electrochemical Capacitors

TLDR: In this paper, the authors demonstrate the importance and great potential of graphene-based composites in the development of high-performance energy-storage systems and demonstrate that the combined advantages of GSs and RuO 2 in such a unique structure are that the ROGSC-based supercapacitors exhibit high specifi c capacitance ( ∼ 570 F g − 1 for 38.3 wt% Ru loading), enhanced rate capability, excellent electrochemical stability ( ∼ 97.9% retention after 1000 cycles), and high energy density (20.1 Wh kg − 1 )

Abstract: Hydrous ruthenium oxide (RuO 2 )/graphene sheet composites (ROGSCs) with different loadings of Ru are prepared by combining sol–gel and low-temperature annealing processes. The graphene sheets (GSs) are well-separated by fi ne RuO 2 particles (5–20 nm) and, simultaneously, the RuO 2 particles are anchored by the richly oxygen-containing functional groups of reduced, chemically exfoliated GSs onto their surface. Benefi ts from the combined advantages of GSs and RuO 2 in such a unique structure are that the ROGSC-based supercapacitors exhibit high specifi c capacitance ( ∼ 570 F g − 1 for 38.3 wt% Ru loading), enhanced rate capability, excellent electrochemical stability ( ∼ 97.9% retention after 1000 cycles), and high energy density (20.1 Wh kg − 1 ) at low operation rate (100 mA g − 1 ) or high power density (10000 W kg − 1 ) at a reasonable energy density (4.3 Wh kg − 1 ). Interestingly, the total specifi c capacitance of ROGSCs is higher than the sum of specifi c capacitances of pure GSs and pure RuO 2 in their relative ratios, which is indicative of a positive synergistic effect of GSs and RuO 2 on the improvement of electrochemical performance. These fi ndings demonstrate the importance and great potential of graphenebased composites in the development of high-performance energy-storage systems.