Effect of simultaneous substitution of Sr and Ca in LaMnO3 thin-film electrode prepared via in situ sol–gel process

Abstract

The utilization of sophisticated deposition techniques for synthesizing metal oxide thin films across various applications is essential, particularly in supercapacitors where thin films have become indispensable. While advanced instruments enhance the quality of the film, they also escalate the manufacturing costs. It is evident that film with fine thickness exhibits high specific capacitance, but the stability is compromised. Conversely increasing the thickness reduces the capacitance, creating a challenging cycle. In this study, we prepare a direct gel-based film via sol–gel process and investigate the electrochemical properties of LaMnO₃ by simultaneously substituting strontium (Sr) and calcium (Ca), and this substituted material was termed as La_0.67Sr_0.165Ca_0.165MnO₃ (LSCMO) synthesized at concentration of x = x₁ + x₂, where x = 0.33 and x₁ = x₂ = 0.165. X-ray diffraction (XRD) studies show the presence of rhombohedral LSMO and orthorhombic LCMO phases. The scanning electron microscopy (SEM) images showed a non-uniform planar structure. Fourier Transform Infrared spectroscopy analysis of the presence of BO₆ Octahedra confirming the perovskite structure. The gel-based thin film was deployed to cyclic voltammetry (CV) analysis for potential window ranging from 0 to 1.4 and the specific capacitance was found to be 4474 mF/cm² at 10 mV/s with the least resistance inside the film which was calculated using the electrochemical impedance spectroscopy (EIS).