Reversible high entropy oxide anode: Interfacial electrocatalysis for enhanced capacity and stability of LiNi_0.8Co_0.1Mn_0.1O₂ lithium-ion batteries

High entropy oxides (HEOs) are considered promising materials for lithium-ion batteries (LIBs) due to their excellent thermal stability at high temperatures and high ionic conductivity. In this study, we utilized the sol-gel method to synthesize a novel HEO, (Co_0.2Ni_0.2Cu_0.2Mg_0.2Zn_0.2)O, with a rock-salt structure, serving as the active anode material for LIBs. The HEO anode exhibited a specific capacity of 450 mAh g⁻¹ under constant-current charge-discharge conditions (current density = 50 mA g⁻¹, C-rate = 0.1C). To address the irreversible capacity loss in the initial stages of HEO anode reactions, a prelithiation modification treatment was applied to the HEO anode surface before assembling it with a LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode to form a full cell. This prelithiation method reduced the irreversible capacitance ratio to 15% and the formation of a mixed layer of lithium carbonate (Li₂CO₃) and lithium phosphate (Li₃PO₄) at the anode-electrolyte interface was studied. This layer enhanced conductivity and hindered the growth of lithium dendrites. Electrochemical results revealed that the HEO anode achieved a specific capacity of 121 mAh g⁻¹ at 20 mA g⁻¹ (0.1C), with a working voltage of approximately 2.4 V and an energy density of 292 Wh kg⁻¹.