Zn_0.5Co_0.5Mn_0.5Fe_0.5Al_0.5Mg_0.5O₄ high-entropy oxide with high capacity and ultra-long life for Li-ion battery anodes

Owing to the robust Li-ion storage properties induced by entropy stabilization effect, transition metal (TM)-based high-entropy oxides (HEOs) are promising electrode materials for high-performance Li-ion batteries (LIBs). In this study, a six-component Zn_0.5Co_0.5Mn_0.5Fe_0.5Al_0.5Mg_0.5O₄ spinel-structured HEO (denoted as 6M-HEO, where M = Zn, Co, Mn, Fe, Al, and Mg) was synthesized using a facile coprecipitation method. When used as an anode of the LIBs, its stable high-entropy nanostructures exhibit high specific capacity (290 mAh·g⁻¹ at a current density of 2 A·g⁻¹), ultra-long cycling stability (maintained 81% of the initial capacity after 5000 cycles), and outstanding rate performance. Such excellent performance can be attributed to two factors. Firstly, its high-entropy structure can reduce the stress caused by intercalation and avoid volume expansion of the HEO nanostructures. As a result, the cyclic stability was significantly enhanced. Secondly, owing to the unique element selection in this study, four active elements (Zn, Co, Mn, and Fe) were incorporated in inactive MgO and Al₂O₃ matrice after the first discharge process, which would allow such high-entropy materials to withstand the rapid shuttle of Li ions.