One-dimensional FeVO4/MWCNT composite electrode to procure an asymmetric supercapacitor device with superior parameters in Na2SO4 electrolyte: synthesis and energy applications

Abstract

Herein, a composite material FVC is prepared via blending the precursors FeVO₄ (FV) and multi-walled carbon nanotubes (MWCNTs) or C, which were further employed for energy accumulation purposes. One of the precursor FeVO₄, was synthesized via hydrothermal method to achieve controlled nanorods like morphology and the composite was synythesized from precursors MWCNT and FeVO₄, using hydrothermal route. To validate the synthesis of all the compounds, their structural and morphological characterizations were performed together with procuring their energy accumulation data via electrochemical studies comprising potentiostatic frequency response analysis (FRA), cyclic voltammetry (CV), and galvanostatic charge–discharge (GCD) measurements. Furthermore, pore volume, area, and diameter distribution were examined via BET investigations. The pore volume of 0.3802 cm³ g⁻¹, surface area of 89.770 m² g⁻¹, and pore diameter of 16.313 nm suggested that the synthesis occurred at the nanoscale. From electrochemical findings, FVC2 achieved a low impedance and high value of specific capacitance (C_s) with an n-factor of about 0.82, exhibiting the least deviation from 1 among all the samples. Based on CV results, FVC2 composite exhibited a C_s value of 1246.12 F g⁻¹ with a potential rate of 2 mV s⁻¹ and 1147.06 F g⁻¹ with an applied current of 0.001 A. The calculated energy density and power density for the FVC2 sample was 159.31 W h kg⁻¹ and 415 W kg⁻¹, respectively. These values together with a good cyclic retention% of 97.23 after continuous exposure to 5000 cycles indicated that FVC2 is ideal for energy accumulation purposes. Furthermore, an asymmetric device FVC2//AC (AC as activated carbon) was formulated to investigate real-life application. The device offered a specific capacitance of 711.53 F g⁻¹ at 10 mV s⁻¹ with a specific energy of 96.1 W h kg⁻¹ and a corresponding power density of 669.2 W kg⁻¹. Notably, the device exhibited a specific capacitance retention of 90.24% after 5000 continuous cycles.