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

[Display omitted] •La2FeMnO6 double perovskites were synthesized using a sol–gel method.•Structural, morphological, vibrational, and optical properties were studied.•The electrochemical properties with its charge storage mechanism were studied for the first time.•The presence of ferromagnetic and anti-ferromagnetic interactions were identified. 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.