High entropy oxides (FeNiCrMnX)3O4 (X=Zn, Mg) as anode materials for lithium ion batteries

Abstract High entropy oxides (HEOs) have attracted the attention of researchers due to their high theoretical specific capacity and structural stability. However, the effect of elements in HEOs on material properties is unknown. In this work, HEOs (FeNiCrMnZn)3O4 and (FeNiCrMnMg)3O4 were successfully synthesized and used as anode materials for lithium ion batteries. The effects of Zn and Mg on the properties of HEOs were studied from the aspects of crystal structure, micro morphology, and surface valence. Results show that Zn enhances the lithium storage performance of HEOs theoretically, which is verified in the later electrochemical performance tests. (FeNiCrMnZn)3O4 is better than (FeNiCrMnMg)3O4 in all aspects of rate properties, cycle performance, and electrochemical impedance spectroscopy. Therefore, the introduction of electrochemically active metals, such as Zn, can improve the performance of HEOs, thereby providing ideas for the subsequent design and application of HEOs.