Study on preparation, magnetic properties and performance of electrochemical supercapacitor based on La2FeMnO6 double perovskite for energy storage applications and their charge storage mechanism

Abstract

La₂FeMnO₆ double perovskites with multifunctional properties have sparked attention in recent years. Nevertheless, there was no direct study elaborating its electrochemical properties for supercapacitor applications. Herein, La₂FeMnO₆ double perovskites were synthesized by the sol–gel method and their structural, morphological, vibrational, optical, magnetic, and electrochemical properties were determined. The X-ray diffraction along with Rietveld refinement showed a cubic structure with Pm-3m space group, and its randomly distributed quasi-spherical morphology was observed from its SEM image. The presence of multiple oxidation states of Mn and Fe in La₂FeMnO₆ was supported by the formation of double exchange interactions between Fe²⁺-O²⁻-Fe³⁺ and Mn³⁺-O²⁻-Mn⁴⁺. The mesoporous structure with 41.79813 m²/g surface area was estimated from the BET analysis. The electrochemical properties of La₂FeMnO₆ were determined using the three electrode setup, and the Cyclic Voltammetric curves possess a quasi-rectangular shape with a specific capacitance of about 10.9 mF g⁻¹ at a current density of 0.5 mA g⁻¹. Dunn’s method illustrate the electrode’s charge storage mechanism and it was determined that the diffusion-controlled process surpasses the capacitive processes at low scan rates. The cyclic stability demonstrated that 96 % of initial specific capacitance was retained even after 5000 cycles which implied the long-term stability and practical use of La₂FeMnO₆ double perovskites. The magnetic analysis showed the presence of ferromagnetic and anti-ferromagnetic interactions both in this system and they are short-range in nature.