LaMnO3-Mn3O4 nanocomposite: Synergetic effect towards high electrochemical performance

Metal oxides have been a focus of research for energy storage devices. Herein, xLaMnO ₃ – (100- x) Mn ₃O ₄ (LMO-MO) composites ( xwt%: 100, 90, 70, and 50) were prepared via one-pot synthesis to elucidate the synergistic effect of the composite constituents on composite’s electrochemical performance. The X-ray diffraction analysis confirmed the presence of individual compounds in the desired ratio and phase. The X-ray photoelectron spectroscopy confirmed the presence of Mn ²⁺ and Mn ³⁺ oxidation states, indicating the presence of both LaMnO ₃ (LMO) and Mn ₃O ₄ (MO) in the composite. The electrochemical performance of composite electrodes prepared using nickel foam was assessed in 1 and 6 M KOH solutions. High specific capacitance measured via cyclic voltammetry of ∼ 770 Fg ⁻¹ at a scan rate of 1 mVs ⁻¹ was recorded for the composite of LMO-MO (70 %: 30 %) in 6 M KOH. At the same time, charge-discharge curves revealed a maximum specific capacitance of around 405 Fg ⁻¹ for an x =70 % sample at a current density of 0.5 Ag ⁻¹. The EIS studies show a reduction in the internal resistance of the composite due to the interconnected structure and reversible faradic process at the interface with a high degree of Coulombic efficiency. A higher overall electrochemical performance of the electrode was recorded in a 6 M KOH electrolyte. The enhanced electrochemical performance of the composite is attributed to efficient charge transfer kinetics through the electrode-electrolyte interface via easy electron hopping pathways between LMO and MO in the composite. These findings suggest that the studied LMO-MO composites could be a potential material for pseudocapacitor energy devices.