Electrochemical Performance of (MgCoNiZn)LiO High-Entropy Oxides in Lithium-Ion Batteries.

High-entropy oxides (HEOs), which are a new class of single-phase solid solution materials, have recently attracted significant attention as an anode material for lithium-ion batteries (LIBs). In this study, (MgCoNiZn)LiO ( = 0.05, 0.15, 0.25, and 0.35) HEOs were synthesized and their electrochemical performances as the anode material were observed in LIBs. X-ray photoelectron spectroscopy (XPS) analysis showed that the increase in the lithium cation concentration causes generation of more oxygen vacancies, which greatly affected the electrochemical performance of (MgCoNiZn)LiO HEO anodes, in the structure. The more the oxygen vacancy concentration in the anode, the higher the discharge capacity in the LIB. The (MgCoNiZn)LiO anode had 1930 mA h g initial and 610 mA h g stable (after 130 cycles) discharge capacities at a current density of 1000 mA g. This work clearly indicated that designing a HEO with abundant oxygen vacancies in the structure was a very efficient strategy to improve the electrochemical performance of the HEO electrode for LIBs.