Maghemite-based anode materials for Li-Ion batteries: The role of intentionally incorporated vacancies and cation distribution in electrochemical energy storage

Anode materials for Lithium-Ion Batteries (LIBs) based on Mo- and V-doped maghemite were prepared by the sol-gel route. High-Resolution Transmission Electron Microscopy (HRTEM) showed the formation of isotropic nanoparticles. The X-ray Photoelectron Spectroscopy (XPS) revealed the presence of Fe3+ and Mo6+ or V4+ for Mo- or V-doped samples, respectively. Rietveld refinement of X-ray Diffraction (XRD) Patterns revealed the distribution of Mo6+ and V4+ cations and showed increase in vacancies. The crystallite size resulted from Rietveld adjustments was in agreement with the HRTEM results. The Extended X-ray Absorption Fine Structure (EXAFS) showed a shrinkage of Fe-O-Fe linkages which is responsible for the reduction of the maghemite cell parameter which agreed with the structural analysis from XRD. The X-ray Absorption Near Edge Structure (XANES) confirmed XPS analysis that Fe3+ is present. Coin cells were assembled and galvanostatic cycling was implemented at various chargedischarge current densities, cyclic voltammograms of Li-ions insertion/extraction processes were obtained and the Electrochemical Impedance Spectroscopy (EIS) was investigated. An exceptional cyclic stability and storage capacity for the V-doped maghemite was observed for low current density. The Mo-doped maghemite has higher capacity retention at high current densities. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study presents the preparation and performance evaluation of anode materials for lithium-ion batteries based on Mo- and V-doped maghemite. The results showed exceptional cyclic stability and storage capacity for V-doped maghemite at low current density, while Mo-doped maghemite exhibited higher capacity retention at high current densities.