Tuning the electrochemical performance of high-entropy oxide nanopowder for anode Li-ion storage via structural tailoring

The development of high-capacity stable electrodes is one of the major goals in the field of Li-ion batteries. High-entropy oxides (HEOs) are promising materials with high stability and Li storage capacity that can be used as anode materials in batteries. In this study, we investigated structural and electronic properties of nanocrystalline (Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2)O, (Cr_0.2Mn_0.2Fe_0.2Co_0.2Ni_0.2)₃O₄, and (Mg_0.2Cr_0.2Mn_0.2Fe_0.2Co_0.2)₃O₄ anode materials and the influence of their chemical composition and crystal structure on Li storage capability. The results show that the spinel phase is more preferable for anode applications compared to rock-salt due to the higher Li storage capacity. The presence of Ni in the HEO structure is favorable for enabling higher capacity; however, it also leads to material instability during charge-discharge cycling. To improve the stability, we replaced Ni with Mg, which resulted in superior stability and high capacity of HEO material during 1000 test cycles. Thus, this study demonstrated an approach for tailoring the chemical and structural properties of HEO electrodes for Li-ion battery applications to obtain high capacity and long-term stability.