Enhanced Electrochemical Performance of MnMoO₄/C Nanoplates in Advanced Battery-Supercapacitor Hybrid Devices

This study focuses on synthesizing MnMoO4 and MnMoO4/C nanoplates (NPs) using a hydrothermal route for application as electrode materials in battery supercapacitor hybrid (BSH) systems. Annealing MnMoO4 NPs under a nitrogen (N2) atmosphere produced a more carbonaceous and porous nature of MnMoO4 NPs than annealing in air. This process incorporated a carbonaceous matrix into the NPs, enhancing their conductivity and electrical properties, which proved to be beneficial for fabricating BSH coin cells. The MnMoO4/C electrode exhibited a specific capacitance and specific capacity of 1280 F/g and 640 C/g, respectively, at a scan rate of 10 mV/s and maintained 91.7% of its capacitance over 5000 charge–discharge cycles. A BSH coin cell was then assembled by using MnMoO4/C as the anode, activated carbon (AC) as the cathode, and a 2 M KOH as an electrolyte. This BSH coin cell demonstrated a specific capacitance and specific capacity of 102.7 F/g and 154 C/g, respectively, at a current density of 1 A/g with an energy density of 48.5 W h/kg and a power density of 1125 W/kg. Compared with MnMoO4, the MnMoO4/C NPs showed significantly improved specific capacitance and long-term stability for electrochemical supercapacitors.