Studies on supercapacitor electrode performance of novel (AlCuCoFeMnNi)₃O₄ high entropy spinel oxide admixed with different carbon‐based additives

Abstract

The present investigation aims to synthesize a novel (AlCuCoFeMnNi)3O4 type high entropy spinel oxide through the sol‐gel and investigate the effect of different carbon‐based additives on charge storage performance. The formation of the inverse spinel phase of [B(AB)O4] type inverse spinel phase was confirmed through the detailed x‐ray diffraction analysis of the synthesized sample. The synthesized spinel phase was indexed with the space group of Fd−3m and has a lattice parameter of 8.2697 Å. The synthesized high entropy oxide (HEO) phase Ni, Co, and Fe coexists in +2 and +3 states. At the same time, Cu in +2 state, Al in +3 state, and Mn in +3 and +4 states confirmed through x‐ray photoelectron spectroscopy. The electrochemical charge storage performance of synthesized HEO was measured through the three‐electrode setup in 2 M KOH aqueous electrolyte solution in two different potential windows, such as −0.2 to 0.4 V and 0.0 to 0.5 V. Different carbon‐based conducting materials such as acetylene black, reduced graphene oxide (RGO), and carbon particles obtained from 10‐hour ball‐milling of used dry cell carbon electrode (CP). The charge storage mechanism changes from electrochemical double layer capacitance to pseudocapacitive type as the potential window varies from −0.2 to 0.4 to 0 to 0.5 V. The value of specific capacitance for an electrode made of HEO with acetylene black, RGO, and CP was found to be 32.67, 7.50, and 4.58 F/g and 30.68, 16.33, and 9.05 F/g in the potential window of −0.2 to 0.4 V and 0 to 0.5 V at a scan rate of 5 mV/s, respectively. The cyclic performance of the developed three electrodes was measured at a scan rate of 100 mV/s for 1000 cycles, and it was found to be 94%, 98%, and 99% for electrodes made of HEO with acetylene black, RGO, and CP, respectively.