Electrochemical\nPerformance of (MgCoNiZn)_1–<i>x</i>Li_<i>x</i>O High-Entropy Oxides\nin Lithium-Ion Batteries

Abstract

High-entropy\noxides (HEOs), which are a new class of single-phase\nsolid solution materials, have recently attracted significant attention\nas an anode material for lithium-ion batteries (LIBs). In this study,\n(MgCoNiZn)_1–<i>x</i>Li_<i>x</i>O (<i>x</i> = 0.05, 0.15, 0.25, and 0.35) HEOs were\nsynthesized and their electrochemical performances as the anode material\nwere observed in LIBs. X-ray photoelectron spectroscopy (XPS) analysis\nshowed that the increase in the lithium cation concentration causes\ngeneration of more oxygen vacancies, which greatly affected the electrochemical\nperformance of (MgCoNiZn)_1–<i>x</i>Li_<i>x</i>O HEO anodes, in the structure. The more\nthe oxygen vacancy concentration in the anode, the higher the discharge\ncapacity in the LIB. The (MgCoNiZn)_0.65Li_0.35O anode had 1930 mA h g^–1 initial and 610 mA h\ng^–1 stable (after 130 cycles) discharge capacities\nat a current density of 1000 mA g^–1. This work clearly\nindicated that designing a HEO with abundant oxygen vacancies in the\nstructure was a very efficient strategy to improve the electrochemical\nperformance of the HEO electrode for LIBs.