Deciphering functional differentiation of elements in high-entropy spinel oxides as ultralong-life anodes in lithium-ion batteries

Abstract

The rational design of high-entropy materials for electrochemical energy storage is hindered by an insufficient understanding of the distinct roles of constituent elements. Taking the spinel-type high-entropy oxide (CoCuMgCrFe)₃O₄ as a model system, this study combines density functional theory calculations with multiscale characterization to systematically reveal the functional differentiation mechanism of the constituent elements during charge/discharge processes. It is demonstrated that Cr, Co, and Fe act as “active elements” significantly enhancing the decomposition kinetics of Li₂O, while Cu and Mg serve as “structural elements” effectively suppressing volume expansion induced by lithium intercalation, thereby improving structural stability. Critically, all high-entropy surfaces exhibit exceptionally strong adsorption of Li₂O intermediates (adsorption energy: −5.35 to −5.64 eV), which is attributed to the synergistic modulation of the electronic structure within the high-entropy environment, thereby accelerating conversion reactions. Bond length analysis identifies the weakening of Li–O bonds near active sites, with Cr exerting the most profound influence. Furthermore, we establish the metal–oxygen bonding radius as a critical descriptor for predicting high-entropy spinel formation. This work unveils the fundamental principle of elemental cooperation in high-entropy oxides, providing crucial guidance for the targeted design of high-performance multicomponent electrodes.