Synthesis of hybrid SmMnO₃/rGO nanocomposites for high performance energy storage applications

The reduction of renewable energy resources like fossil fuels leads to a focus on electrochemical energy storage systems, which are remarkable and sustainable in day-to-day life. Furthermore, the challenge in supercapacitors is to fabricate a hybrid energy storage device with high energy density and longer discharge time. Herein, the samarium manganese oxide/reduced graphene oxide nanocomposites (SmMnO3/rGO NCs) were synthesized via ultrasonic-assisted hydrothermal technique and their structure, vibrational modes, morphology, and elemental composition were investigated by X-ray diffraction (XRD), Raman, Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray Spectroscopy (EDX), High Resolution Transmission Electron Microscope (HRTEM), and Selected Area Electron Diffraction (SAED) analysis. Furthermore, the electrochemical activities were analyzed by Cyclic voltammetry (CV analysis), Galvanostatic charge-discharge (GCD analysis), and the Electrochemical impedance spectroscopy (EIS analysis). The CV study of SmMnO3/rGO NCs possesses a higher specific capacity (C-specific) of 392.95 C/g at a 10 mV/s scan rate compared to SmMnO3. From Trasatti and Dunn's technique, the synthesized SmMnO3/rGO NCs deliver the total (q '(To)), outer (q '(ou)), and inner q '(in)) capacities of in 490.19, 208.53, and 281.65 C/g respectively. The EIS analysis of SmMnO3/rGO NCs delivers low R-s (Solution resistance) and R-ct (Charge-transfer resistance) of 0.26 Omega and 0.06 Omega. Moreover, the hybrid supercapacitor (SmMnO3/rGO//AC) device (HSC) was fabricated and tested for electrochemical performances which delivered excellent specific capacity (C-specific4) of 205.71 C/g at 0.5 A/g current density, superior energy density (E-device) of 48.28 Wh/kg, and the power density (P-device) of 422.49 W/kg at 0.5 A/g current density, and possesses better capacitive retention of 49.63% and the coulombic efficiency of 100.12% over 6000 charge-discharge cycles.