Elevating oxygen vacancy of Co-free high-entropy oxide anode by lithium doping enables long-cycle lithium-ion batteries

High-entropy oxides (HEOs) have attracted significant attention as potential anode materials for lithium-ion batteries (LIBs) owing to their exceptional theoretical capacity. In this work, a cobalt-free high-entropy oxide (HEO) anode material is prepared through a solid-state method and doped with lithium ions. Moreover, the stability mechanism and electronic properties of the material are characterized using experiments and density functional theory (DFT) calculations. The prepared HEOs [Li x (Cr 0.2 Fe 0.2 Ni 0.2 Mn 0.2 Cu 0.2 ) 1-x ] 3 O 4 (x = 0, 0.05, 0.1, 0.2) are all have a single-phase spinel structure. The undoped (Cr 0.2 Fe 0.2 Ni 0.2 Mn 0.2 Cu 0.2 ) 3 O 4 (HEO-0) maintains a specific capacity of 632.3 mAh g −1 following 250 cycles at 0.1 A g −1 . This performance can be further enhanced through lithium doping. In particular, the HEO-10 (x = 0.1) achieves a specific capacity of 765.0 mAh g −1 after 250 cycles at 0.1 A g −1 , while preserving 181.4 mAh g −1 following 1500 cycles at 1 A g −1 . This performance enhancement originates primarily from lithium-induced oxygen vacancies, which generate additional active sites for lithium storage and accelerate ion transport kinetics.