Uniform MnCo2O4.5 porous nanowires and quasi-cubes for hybrid supercapacitors with excellent electrochemical performances

Abstract

In this work, uniform MnCo₂O_4.5 nanowires (NWs) on stainless steel foil (SSF) were prepared through a facile, cost-efficient, and eco-friendly hydrothermal method at 120 °C with a post-calcination process in air. The microstructure of MnCo₂O_4.5 samples could be tuned at different hydrothermal temperatures and quasi-cubes (QCs) were obtained in high yield at 150 °C. The MnCo₂O_4.5 NW powder peeled off from the SSF delivered an outstanding capacity of 248.62 C g⁻¹ at 1 A g⁻¹ with a capacity preservation of 179.43 C g⁻¹ at 8 A g⁻¹, while the QCs exhibited 177.19 and 111.73 C g⁻¹, respectively. To assess the possibility of its actual applications, a hybrid supercapacitor (HSC) device has been assembled by utilizing these MnCo₂O_4.5 NWs (QCs) and activated carbon (AC) as the cathode and anode, respectively. The MnCo₂O_4.5 NWs//AC HSC delivered a maximum capacity up to 116.95 C g⁻¹ and extraordinary cycling durability with only 3.56% capacity loss over 5000 cycles. Besides, the MnCo₂O_4.5 NWs//AC HSC achieved a maximum energy density of 25.41 W h kg⁻¹ at a power density of 782.08 W kg⁻¹, and for the QC-based HSC, it showed a lower energy density of 20.54 W h kg⁻¹ at 843.34 W kg⁻¹. These remarkable electrochemical properties demonstrate that the porous MnCo₂O_4.5 NWs and QCs may serve as promising cathodes for advanced hybrid supercapacitors with superior performance, and the present synthetic methodology may be applied to the preparation of other cobalt-based binary metal oxides with excellent electrochemical properties.