Structural and Electrochemical Investigations on Nanocrystalline High Entropy Spinel Oxides for Battery‐Like Supercapacitor Applications
N. Sreenivasulu, Umesh Kumar, Kancherla M. V. V. Madhav, Tiju Thomas, Subramshu S. Bhattacharya
Abstract
Abstract High entropy oxides (HEOs) are a novel class of materials with a stable single‐phase structure that is often entropy stabilized and possess many interesting functional properties. In this work, we report a nanocrystalline spinel‐based high entropy oxide (SP‐HEO) ‐ (Al 0.2 Co 0.2 Cr 0.2 Mn 0.2 Ni 0.2 ) 3 O 4 and present an assessment of its electrochemical performance. A reverse co‐precipitation (RCP) method was used for synthesis, followed by a suitable heat‐treatment/calcination step that was adjusted to form a single‐phase nanocrystalline powder. Structural characterisation revealed that the single‐phase system was stable upto 850 °C. Nitrogen adsorption studies showed a large specific surface area of 90 m 2 g −1 in the case of the SP‐HEO calcined at 550 °C. The SP‐HEO powders were investigated as electrodes for battery‐like supercapacitor behaviour in an aqueous alkaline electrolyte ‐ KOH. The SP‐HEO powder calcined at 550 °C exhibited the highest specific capacity of 318 mAh g −1 at a current density of 1 A g −1 . The high electrochemical performance of the mesoporous SP‐HEO makes it a promising electrode material for energy storage devices.