Fabrication of spinel MCr2O4 (M = Ni and Co) nanostructures as positive electrode materials for high-performance supercapacitors

Abstract

The demand for a low-cost and effective energy storage system drives researchers to develop advanced electrode materials for energy storage devices. Recently, Cr-based bimetallic spinel materials have gained attention as potential electrodes for supercapacitors (SCs) due to their low cost, natural abundance, high mechanical strength, and favorable electrochemical properties. In this study, spinel-structured low-cost and robust MCr2O4 (M = Ni and Co) electrode materials were synthesized by the simple coprecipitation strategy for high-performance SCs. The structural morphologies and electrochemical characteristics of spinel materials were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD) techniques. Because of its more electroactive sites and rich redox activity, the fabricated CoCr2O4/NF electrode exhibited a higher specific capacitance (capacity) of 550 F g−1 (275 C g−1) at a current density of 1 A g−1 compared to the NiCr2O4/NF electrode (442 F g−1 (221 C g−1)). Moreover, CoCr2O4/NF promotes rapid electron-ion transport and maintains its integrity of structure over extended cycling periods, resulting in excellent cyclability (preserving at 94.15 % after 5000 cycles). More interestingly, the asymmetric device (CoCr2O4/NF//AC/NF) was constructed using positive (CoCr2O4/NF) and negative (AC/NF) electrodes delivered a noteworthy specific capacitance of 114.12 F g−1 (194 C g−1 at 1 A g−1) and cyclic durability of 89.4 % retention over 5000 charging-discharging cycles. The CoCr2O4/NF//AC/NF device reached a high energy density of 45.8 Wh kg−1 at a power density of 849.9 W kg−1, demonstrating its potential for real applications.