Investigation of La2FeO4-rGO nanocomposite electrode material for symmetric and asymmetric supercapacitor

Ruddlesden-Popper (RP) oxides, represented by the general formula of A_n+1B_nO_3n+1, are emerging as promising electrode materials for supercapacitors (SCs) electrodes due to their stable crystal structure, rich oxygen vacancies, and good reversible redox behavior. In this study, La₂FeO₄ and 2D reduced graphene oxide (rGO) were synthesized via a solid-state reaction method and Modified Hummer method, respectively. Nanocomposites of La₂FeO₄/rGO in a varying weight ratios (0:1, 1:0, 1:1, 1:2, 1:3, 1:4, and 1:5 wt %) were subsequently synthesized through a hydrothermal method. The synthesized La₂FeO₄ and optimized La₂FeO₄-rGO (1:4) nanocomposite were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), high-resolution SEM (HR-SEM), high-resolution transmission electron spectroscopy (HR-TEM) techniques and Brunauer-Emmett-Teller (BET) techniques. Electrochemical measurement evaluated in a 3 M KOH electrolyte solution revealing the remarkable performance of the composites. Fabricated symmetric supercapacitors (SSCs) based on La₂FeO₄-rGO (1:4)/La₂FeO₄-rGO (1:4) have demonstrated the gravimetric capacitance values of 633, 298, 226, 139, and 72 F/g at current densities of 1, 2, 3, 5, and 10 A/g, respectively. Similarly, an asymmetric supercapacitor (ASC) configuration La₂FeO₄-rGO (1:4)/rGO have shown capacitance 197, 160, 108, 89, and 58 F/g values at the same current densities. SSCs and ASCs assemblies have exhibited outstanding capacitance retention (91.1 % for SSCs, 99.9 % for ASCs) and high coulombic efficiency (99.5 % for SSCs, and 74 % for ASCs). Additionally, these devices displayed a maximum specific power density (7.8 KW/kg for SSCs, and 20 KW/kg for ASCs) and a maximum specific energies (148 Wh/kg for SSCs, and 70 Wh/kg for ASCs).