Effects of high-entropy carbonate precursors on the electrochemical properties of NaCl-based high-entropy ceramics as anode materials

In this paper, powders of (Mg 0.2 Co 0.2 Ni 0.2 Zn 0.2 Cu 0.2 )O high-entropy ceramic oxides (HEO S ) were prepared by a hydrothermal method. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM–EDS) and electrochemical technology were used to study the effect of different hydrothermal times on the performance of the HEO S . The obtained results showed that after prolonged hydrothermal treatment, crystalline high-entropy carbonates (Mg 0.33 Ni 0.33 Co 0.33 Zn 0.33 )CO 3 (HECO 3 s) were formed, which facilitated crystal development and grain size reduction of their calcined product (Mg 0.2 Co 0.2 Ni 0.2 Zn 0.2 Cu 0.2 )O. The reduced grain size led to an increase in the specific surface area, which enhanced the electrochemical activity of Co and Ni in the high-entropy oxides and simultaneously considerably improved the electrochemical behavior of the product, resulting in an increase in the charge–discharge capacity from 465.8F/g to 921.1F/g at 0.1 A/g. The Jahn–Teller synergy of Co, Ni, and Cu ions stabilized the crystal structure during Li + intercalation and deintercalation. Good charge/discharge reversibility and high capacity retention were maintained after 500 charge/discharge cycles.