Design and Fabrication of Advanced Cathode and Anode Materials for Hybrid Supercapacitors Based on Graphitic Carbon Quantum Dot-Decorated Reduced Graphene Oxide Composite Aerogels

A graphene aerogel-based composite has recently been deemed as a prospective electrode material for advanced energy storage devices. Here, carbon quantum dots (CQDs) are simultaneously utilized as the conductive agents, intercalators, and stable links to boost the electrochemical property of graphene composite aerogels due to their many natural advantages. The three-dimensional (3D) N, S dual-doped CQDs/reduced graphene oxide (rGO)/NiCo2S4 composite aerogel (N,S-CQDs/rGO/NiCo2S4) is first fabricated through a one-pot hydrothermal way and utilized as a supercapacitor cathode, exhibiting a large specific capacity of 162.6 mA h g–1 at 1 A g–1, splendid rate property with 77.3% capacity retention at 50 A g–1, and good cyclic stability with 87.5% capacity retention after 5000 cycles, which originates from the synergistic interaction of the 3D reticulation N,S-CQDs/rGO aerogel framework with excellent conductivity and structural stability and NiCo2S4 nanoparticles with abundant Faradaic redox reactions. Further, the resulting N,S-CQDs/rGO/NiCo2S4 cathode is coupled with the prepared N,S-CQDs/rGO anode to assemble a hybrid supercapacitor (HSC) device, manifesting a superior energy density (51.0 W h kg–1), an ultrahigh power density (14.4 kW kg–1), and good cyclic stability with 82.9% capacitance retention after 10,000 cycles. The present study offers a good strategy for designing and exploiting superior energy storage systems by utilizing the CQDs/rGO composite aerogel simultaneously as both the cathode and anode.