Oxygen-deficient tungsten oxide nanorods with high crystallinity: Promising stable anode for asymmetric supercapacitors

Highlights: • Oxygen vacancy has been introduced in WO₃ nanorods via an effective approach. • The hydrogenation obviously improves the crystallinity of WO_3-x electrode. • The WO_3-x electrode yields a capacitance of 1.83 F cm⁻² with excellent stability. Asymmetric supercapacitors (ASCs) represent an effective electrochemical energy storage device with wider potential windows, which may lead to a substantial increase in the energy density and power density of the device. Unfortunately, their development is severely restricted by the carbon-based negative electrodes with low energy density. In this work, we demonstrate the facile synthesis of engineering WO_3-x electrode on carbon cloth via hydrogenation, which achieves excellent electrochemical performance as a negative electrode for ASCs. The enhanced crystallinity and introduction of oxygen vacancy synergistically contribute to more reversible redox reactions, faster ion diffusion and charge transfer rates. The as-obtained WO_3-x electrode reaches a high areal capacitance of 1.83 F cm⁻² at 1 mA cm⁻², and an outstanding electrochemical durability with high capacity retention of 74.8% after 10000 cycles. All these results open a new way to the construction of high-performance anodes for ASCs.