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

Abstract

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.