All-in-one supercapacitors with high performance enabled by Mn/Cu doped ZnO and MXene

Here, we report the development of high-performance supercapacitor devices using manganese-doped zinc oxide nanowires (Mn-doped ZnO NWs) and copper-doped zinc oxide nanoparticles (Cu-doped ZnO NPs) as a positive electrode with MXene as a negative electrode. Both transition metal (TM)-based electrodes were used separately with MXene, and the performance was tested. When used in combination with MXene as a second electrode, TM-ZnO samples displayed a major increase in the supercapacitors' performance. The highest-performance supercapacitor recorded values of 151 F/g specific capacitance along with 84 Wh/kg energy density and a power density of 75 kW/kg. Electron paramagnetic resonance and photoluminescence spectroscopy of Mn/Cu-doped ZnO reveals intrinsic and extrinsic defect signals, which were discussed and attributed to the enhancement of the capacitive performance. The presence of the aforementioned defects optimizes the intrinsic properties and boosts the reaction kinetics, thus providing increased electrochemical activity and superior supercapacitor device performance.

Automated summary

In this study, high-performance supercapacitor devices were developed using manganese-doped zinc oxide nanowires and copper-doped zinc oxide nanoparticles as a positive electrode, with MXene as a negative electrode. The performance of transition metal-based electrodes in combination with MXene was found to significantly enhance the supercapacitors' performance. The highest-performance supercapacitor achieved a specific capacitance of 151 F/g, an energy density of 84 Wh/kg, and a power density of 75 kW/kg. The presence of intrinsic and extrinsic defects in the Mn/Cu-doped ZnO was found to optimize the intrinsic properties and improve reaction kinetics, leading to enhanced electrochemical activity and superior supercapacitor device performance.