Synthesis, characterization, and evaluation of polyaniline-modified (FeCoNiCrMn)₃O₄ high-entropy oxide as an anode material for lithium-ion batteries

This paper investigates the microstructure and electrochemical properties of Polyaniline-Modified (FeCoNiCrMn)₃O₄, a high-entropy oxide, with a focus on its potential as an anode material in lithium-ion batteries. The high-entropy oxide (FeCoNiCrMn)₃O₄, featuring a spinel structure, was synthesized via a two-step process: mechanical milling of constituent oxides followed by a calcination treatment at 900 °C. To investigate the structure of the synthesized powder, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were employed. The results demonstrate the successful synthesis of a single-phase spinel structure with a homogeneous distribution of elements, exhibiting perfect uniformity. A Polyaniline (PANI) coating layer was subsequently applied to the HEO particles using a polymerization method. The presence of the PANI layer was confirmed using Fourier Transform Infrared Spectroscopy (FTIR). Results from impedance analysis revealed a substantial decrease in the Z-value of the PANI-modified sample compared to the pure HEO, indicating that the modified anode exhibits enhanced electrical conductivity. It is evident that the PANI coating layer has a significantly positive attribution to the electrochemical performance of the anode material by enhancing its structural stability and inhibiting excessive solid electrolyte interphase (SEI) growth during cycling. The correlations between the HEO structure and the PANI layer with the electrochemical performance of the anode material are discussed.