Amorphous RuO2 coated on carbon spheres as excellent electrode materials for supercapacitors

Abstract

Significant enhancement in supercapacitor performances was achieved by the first fabrication of amorphous RuO₂ hybrid by utilising carbon spheres as templates. The as-prepared carbon spheres (Cs)/RuO₂ and reduced carbon spheres (rCs)/RuO₂ composites exhibit high specific capacitances of 387 F g⁻¹ (44.2 wt% RuO₂ loading) and 614 F g⁻¹ (72.6 wt% RuO₂ loading) at a current density of 1 A g⁻¹ at 2 mg cm⁻² loading mass, showing remarkable rate capability with capacitances of 336 F g⁻¹ and 491 F g⁻¹ at a current density of 20 A g⁻¹ and excellent cycling stability with capacity retention of 97.7% and 90.8% for 5000 cycles. The enhanced electrochemical performances could be attributed to the unique structure of the resulted composites as well as the high utilization of well-dispersed RuO₂ nanoparticles on the carbon surface. These results demonstrate the great potential of carbon sphere-based composites in the development of high-performance electrode materials for supercapacitors.