Operando synchrotron transmission X-ray microscopy study on (Mg, Co, Ni, Cu, Zn)O high-entropy oxide anodes for lithium-ion batteries

(Mg,Co,Ni,Cu,Zn)O, a high-entropy oxide, has recently been proposed as an anode material for lithium-ion batteries (LIBs). It exhibits excellent cyclic stability, which is attributed to the high-entropy stabilization effect, as reported in previous studies. The presence of Mg may also help stabilize the electrode by helping conserve its original lattice structure during charging and discharging. In this work, (Mg,Co,Ni,Cu,Zn)O oxides with various amounts of Mg were synthesized, namely, (Mg,Co,Ni,Cu,Zn)O, (Mg0.8,Co,Ni,Cu,Zn)O, and (Co,Ni,Cu,Zn) O. To explore the impact of Mg in LIBs, cyclic voltammetry and galvanostatic charge-discharge measurements were conducted. In addition, changes in morphology were observed using operando synchrotron transmission Xray microscopy. Through the aforementioned analyses, the role of magnesium was investigated, which is expected to assist in the development of high-entropy oxide electrodes for LIBs.