(MgCoNiCuZn)O with particular microstructure and distinctive electrochemical performance prepared using ultrafast high-temperature sintering

Ultrafast high-temperature sintering (UHS) based on Joule heating of graphic felt with a 103∼104 ℃/min heating rate enabled densification of ceramics in just a few seconds. The microstructure and electrochemical performance of (MgCoNiCuZn)O was systematically investigated. The equiaxed high-entropy grains were fully encapsulated in the Cu2O/Cu shell. This microstructure was a unique characteristic of (MgCoNiCuZn)O sintered by UHS and had not been found in materials prepared by other sintered methods. The Cu2O/Cu came from the reduction of CuO with the assistance of graphic felt, applied electric field and high temperature during UHS process. Because of this special microstructure, the discharge capacitance of the as-sintered material gradually increased as the cycles proceeded during the electrochemical experiment. After 10,000 cycles, the discharge specific capacitance ranged from 27.48 F/g to 39.84 F/g, which is an increase of 44.96 %. This work provides an idea for preparing electrochemical energy storage materials by using UHS technology.