A Cobalt‐Free Li(Li_0.16Ni_0.19Fe_0.18Mn_0.46)O₂ Cathode for Lithium‐Ion Batteries with Anionic Redox Reactions

Abstract

Abstract Lithium‐rich, Mn‐based layered oxides Li 2 MnO 3 ‐LiMO 2 (M=Ni, Co) have been considered as promising cathode candidates owing to their high capacity. However, the resources shortage and high price of cobalt make it imperious to substitute cobalt with other high‐abundance elements. Here, we synthesized a low‐cost, cobalt‐free, Fe‐substituted oxide material, Li(Li 0.16 Ni 0.19 Fe 0.18 Mn 0.46 )O 2 . It exhibited a high reversible capacity of 169.2 mAh g −1 after 100 cycles and maintained an extraordinarily high discharge potential during cycling. X‐ray photoelectron spectroscopy and DFT calculations revealed that super iron Fe IV exists in the delithiated state, and oxygen participates in the redox reaction in addition to the Ni 2+ /Ni 4+ and Fe 3+ /Fe 4+ redox couples. The anionic oxidation preferentially occurred on oxygen with a Li−O−Li configuration and with oxidized Fe and Ni coordination.