Effect of Synthesis Conditions on the Composition, Local Structure and Electrochemical Behavior of (Cr,Fe,Mn,Co,Ni)3O4 Anode Material

Disordered high entropy spinels (HES) (Cr,Fe,Mn,Co,Ni)₃O₄ were obtained by solid-state synthesis and co-precipitation using various powder precursors. They were characterized by a complex of physico-chemical methods and investigated as anode materials for lithium-ion batteries (LIBs). According to XRD and TEM data, the materials are single-phase. The structural characterization of the samples obtained at 773, 973, and 1273 K was determined using Raman and Mössbauer spectroscopy, and magnetic measurements. The degree of spinel inversion and lattice distortion (microstrains) decrease with increasing synthesis temperature, while the crystallite size increases. The insufficient nickel content in the samples ensures a more uniform distribution of iron cations in both sublattices, which leads to an increase in the lattice parameters and has a positive effect on the de-/lithiation. Repeated ball-milling of HES material, prepared by co-precipitation, increases its specific capacity from 284 mAh g⁻¹ to 492 mAh g⁻¹ at a current density of 100 mA g⁻¹ after 25 cycles. Besides, the smaller crystallite size reduces the volume changes in the materials during de-/lithiation.