Rapid and stable energy storage using MoN/Mo2N composite electrodes

Abstract

Molybdenum nitride-based composites, specifically the two-dimensional MoN/Mo₂N variants, emerge as promising electrode materials for next-generation energy storage devices. This research presents a facile synthesis approach involving a mechanochemical method followed by heat treatment at 900 ֯C in a nitrogen atmosphere to produce the MoN/Mo₂N composite material. Crystallographic analysis using X-ray diffraction (XRD) and morphological characterization via high-resolution scanning electron microscopy (HRSEM) were conducted. The electrochemical evaluation demonstrated remarkable supercapacitor performance, with a specific capacitance of 306.7 F/g at 1 A/g, highlighting exceptional charge storage capacity. Even at a higher current density of 2 A/g, the composite maintained substantial reversible capacity (198.6 F/g), higher capacitance retention (95.7 %), and Coulombic efficiency (86.2 %) over 6000 cycles, showcasing its robust stability. At a challenging current density of 10 A/g, the specific capacitance remained high at 85.4 F/g. Detailed charge storage mechanism analysis, employing the Dunn method, revealed a complex interplay of capacitive and diffusive processes. Particularly noteworthy was the predominance of capacitive behavior, constituting 78.4 % at an accelerated scan rate of 100 mV/s. This observation underscores the material's advantageous propensity for a higher proportion of capacitive behavior in the charge storage mechanism at elevated scan rates, making it well-suited for applications requiring rapid energy storage and release.