Electronic structural alterations in LiMn₂O₄ doped with cobalt and vanadium

This study utilized Density Functional Theory (DFT) calculations, implemented through the Quantum ESPRESSO package, to assess the impact of cobalt and vanadium co-doping on the electrochemical performance and electronic structure of LiMn₂O₄ (LMO). Analysis of the Density of States (DOS) diagrams indicates that vanadium and cobalt introduce peaks in the conduction band and near the Fermi level in the valence band , respectively, leading to enhanced electrical conductivity . The electronic structural analysis showed a reduction in the band gap of LMO from 1.6 eV to 0.8 eV in the co-doped LCVMO. To validate the DFT results, the electrochemical properties of LCVMO were examined, revealing that the capacitive current contributed 33.9 % in the LMO sample and 29.6 % in the LCVMO sample, corresponding to a 4 % decrease in the scan rate at 1 mV/s, which further supports the increased electrical conductivity . Electrochemical impedance spectroscopy (EIS) was conducted on both electrodes to evaluate the lithium-ion diffusion characteristics. The co-doped materials exhibited higher lithium-ion diffusion rates, with values of 2.69 × 10⁻ 12 cm 2 /s for the LMO sample and 3.42 × 10⁻ 12 cm 2 /s for the LCVMO sample.