Precursor-driven morphological control of manganese molybdates nanoflakes for high-performance battery-supercapacitor hybrid devices

This work details a facile hydrothermal synthesis of MnMoO 4 nanostructures (NSs) with controlled morphology. By employing different manganese salt precursors, such as chloride, nitrate, and acetate, with a consistent molybdenum precursor source, distinct nanoflakes, nanospheres, and quasi-nanospheres architectures were successfully obtained. The nanoflake-based electrode exhibited a larger specific surface area of 42.04 m 2 /g. Electrochemical characterization revealed that an electrode fabricated from the MnMoO 4 nanoflakes (MMO-1) delivered a remarkable specific capacitance/capacity of 1008.9 F/g (504.4 C/g) at 10 mA/g in a 2 M KOH. The optimised MMO-1 electrode also demonstrated excellent cycling stability, retaining 89.8 % of capacitance with a Coulombic efficiency of 98.3 % over 10,000 cycles. Furthermore, the ABSH coin cell device achieved a superior capacitance/capacity of 133.7 F/g (214 C/g), a specific energy of 47.5 Wh/kg at a specific power density of 1923.1 W/kg, and maintained 80.1 % capacitance retention with 96.7 % Coulombic efficiency after 5000 cycles.