Porous hollow high entropy metal oxides (NiCoCuFeMg)3O4 nanofiber anode for high-performance lithium-ion batteries

High-entropy metal oxides (HEOs), which incorporate five or more distinct metal ions in a unified crystalline lattice, exhibit outstanding electrochemical capacity and catalytic properties for energy storage and intermediate reaction conversion, making them highly regarded materials for lithium-ion batteries (LIBs). The porous (NiCoCuFeMg)3O4 high entropy metal oxide hollow nanofibers (H-F-HEO) were fabricated using a straightforward electrospinning technique and morphology was controlled using two types of polymers with different decomposition temperatures. The porous hollow structure significantly contributed to the diffusion of lithium ions. The Ni2+, Co2+, and Cu2+ ions played a role in achieving reversible capacity, whereas the Fe2+ ions significantly influenced the high-rate characteristics, and the Mg2+ ions affected the stabilization of the crystal structure. H-F-HEO achieved a high reversible capacity of 907 mA h g−1, maintaining approximately 100 % of its initial capacity at a current density of 2 A/g for over 300 cycles. The extended cycling stability can be ascribed to the unique crystal structure and narrow bandgap of H-F-HEO, as verified by density functional theory (DFT) calculations. Additionally, the electronic states of the metals in the HEO system facilitated strong hybridization with neighboring oxygen atoms, thereby fine-tuning the metallic characteristics and enhancing the conductivity of the HEO system. Therefore, synthesizing of the (NiCoCuFeMg)3O4 HEO provides a strategic approach for fabricating materials with a stable structure and exceptional performance as promising anode materials for next-generation high-performance LIBs.