Microwave-Assisted Rapid Synthesis of Self-Assembled T-Nb2O5 Nanowires for High-Energy Hybrid Supercapacitors

Recently ion-intercalation hybrid supercapacitors, with high energy density at high power density, have been widely investigated to meet ever-increasing practical demands. Here, a unique hybrid supercapacitor has been designed and fabricated using self-assembled orthorhombic-phase niobium oxide@carbon (T-Nb2O5@C) nanowires as an anode and commercially available activated carbon as a cathode. The 3D-interconnected T-Nb2O5@C nanowires have been synthesized through a highly efficient microwave-solvothermal method, combined with subsequent thermal treatment. The experimental parameters (e.g., time and temperature) can be easily programmed, and the synthesis time can be significantly shortened, thus enabling the buildup of abundant recipes for the engineering of scaled-up production. The Li-ion intercalation pseudocapacitance electrode, made from the as-formed self-assembled T-Nb2O5@C nanowires, shows excellent charge storage and transfer capability. When assembled into a hybrid supercapacitor with a cathode of activated carbon, a high energy density of 60.6 Wh kg(-1) and a high power density of 8.5 kW kg(-1) with outstanding stability are achieved. In virtue of easy optimization and programmability of the synthetic strategy, and the remarkable electrochemical performance, the self-assembled T-Nb2O5@C nanowires offer a promising anode for asymmetric hybrid supercapacitors.