MnMoO₄-S nanosheets with rich oxygen vacancies for high-performance supercapacitors

The structure of materials is closely related to their electrochemical properties. MnMoO4 materials have good stability as supercapacitors but their specific capacitance performance is not excellent. To improve electrochemical performance of MnMoO4, this study conducts secondary hydrothermal treatment in thiourea solution on MnMoO4 electrode material grown on nickel foam synthesized by traditional hydrothermal method. A more compact S-doped MnMoO4 electrode material with more oxygen vacancies and higher specific capacitance was obtained. At the current density of 1 A g(-1), the specific capacitance of the composite material reached 2526.7 F g(-1), which increased by 140.9% compared with that of ordinary MnMoO4 material. The capacitance retention rate of the composite material was 95.56% after 2000 cycles at 10 A g(-1). An asymmetric supercapacitor was fabricated using S-doped MnMoO4 as the positive electrode, activated carbon as the negative electrode, and 6 mol L-1 KOH solution as the electrolyte. The specific capacitance of the assembled supercapacitor was 117.50 F g(-1) at 1 A g(-1), and a high energy density of 47.16 W h kg(-1) at the power density of 849.98 W kg(-1) was recorded. This method greatly improves the specific capacitance of MnMoO4 through simple processing, which makes it have great application potential.