Four-component high entropy spinel oxide as anode material in lithium-ion batteries with excellent cyclability

Nowadays, energy storage technologies are in focus of public interest, especially in the field of the automotive industry. Lithium-ion batteries (LIBs) are evaluated as one of the most advanced energy storage devices because of their high energy density, which can meet rapidly growing energy requirements. Graphite based anode materials in LIBs are reaching their fundamental limits, especially their specific capacities. Recently, it has been demonstrated that high entropy oxides (HEOs) possess promising and unexpected electrochemical properties, such as remarkable reversible capacity and cycle stability due to the high entropy of the system. The highly disordered structure can provide self-healing properties resulting in regeneration of the capacity by applying low current densities. In addition, they can alleviate volume changes during the cycling process, unlike simple oxides. Among the various types of high entropy oxides, spinel-structured HEOs are the most studied because they ensure the three-dimensional transport of lithium ions ensuring high rate capability. Herein, we report a simple method of preparation of high entropy oxide (HEO) with a spinel structure consisting of 4 different elements (Co, Fe, Cr, Ni). The prepared HEO exhibited excellent cycle stability during (116 mAh.g^-1) 500 cycles at a current density of 500 mA.g^-1, which confirms their usage as anode active materials in lithium-ion batteries.