Porous powder synthesis of (FeCoCrMnNi)3O4 high entropy ceramic and its supercapacitor applications

High entropy materials are becoming more and more popular in energy storage field of supercapacitors because of their unique structure and modulated functional characteristics, but their low conductivity and instability of electrode structure limit their further electrochemical performance. In this paper, we use polyethylene glycol (PEG) with different molecular weights to modify the surface morphology of the high entropy oxides (FeCoCrMnNi)3O4 in an attempt to improve their supercapacitors performance. The PEG was used as a pore-making agent to prepare porous high entropy oxides powder with a large specific surface area of 92.7559 m2 g−1, providing more active sites and ion transport channels. A high specific capacitance of 204 F g−1 at 0.5 A g−1 and good cycle performance of 60.4 % capacitance retention after 10,000 cycles were obtained. Besides, an asymmetric device with improved energy density of 53 W h kg−1 and the power density of 400.8 W kg−1 were reached via the designed microstructure of the high entropy oxide electrode.