Synergistic engineering of fluorine doping and oxygen vacancies towards high-energy and long-lifespan flexible solid-state asymmetric supercapacitor.

The low electron conductivity and scarce electrochemically active sites impede the practical application of bimetal oxides for supercapacitors. Herein, fluorine-doped and oxygen vacancy–enrich NiMoO₄ (F-NiMoO_4-x) nanosheet arrays are constructed via facile hydrothermal and wet chemical reduction processes on carbon cloth fibers (CFC). The structural and electronic properties in F-NiMoO_4-x can be modulated by the synergistic effect of dopant F and O vacancies to boost the electrical conductivity and enhance Faradaic redox sites. The obtained flexible F-NiMoO_4-x@CFC as a self-supporting electrode can provide superior areal capacitance of 2.45 F cm⁻² at 1 mA cm⁻², 6-fold higher than that of pristine NiMoO₄@CFC electrode. Moreover, the assembled flexible solid-state asymmetric supercapacitor (ASC) delivers an impressive energy density of 336.5 μWh cm⁻² at a power density of 1790 μW cm⁻² with a wide voltage window of 1.8 V. Moreover, the ASC can work at different bending angels with an ultralong and stable lifespan. [ABSTRACT FROM AUTHOR]