High-performance silver-quantum-dots-modified scalable manganese oxides nanostructures for supercapacitors

Transition metal oxides-based supercapacitors (SCs) as new potential energy storage devices have played a crucial role due to their inherit advantages. Here, hybrid manganese oxide matching silver-quantum-dots (MnOx- Ag-QDs) materials were successfully prepared and undergone nanostructural evolution by electrochemical cycling protocol. A significant Ag-QDs band regulates the transition of MnO2 nanosheets, bringing extremely transferred region between MnO2 and metallic Ag-QDs, and uniquely endowing leaves-like nanostructure. Due to the unique nanostructure and Ag-QDs adjustment including introducing defects, regulating Mn valence states, and enhancing electroactive transfer, the cycling MnOx-Ag-QDs electrode exhibits excellent electrochemical performance, e.g., broadening potential window (0-1.2 V), superior specific capacitance (2101 F g-1 at 0.9 A g-1), and excellent cycling stability (96.14% of the original at 8 A g-1 after 6000 cycles). The assembled ASCs display a high operating voltage, a superior specific capacitance and an exceptional energy density. This work provides new insights for modifying high-performance manganese oxides based electrodes and applications for next generation advanced devices of electrochemical energy and power conversion.

Automated summary

Transition metal oxides-based supercapacitors with hybrid manganese oxide and silver-quantum-dots (MnOx- Ag-QDs) electrodes were prepared through electrochemical cycling, resulting in a unique leaves-like nanostructure. The MnOx-Ag-QDs electrode exhibited excellent electrochemical performance, including a wide potential window, high specific capacitance, and superior cycling stability. The assembled supercapacitors demonstrated high operating voltage, specific capacitance, and energy density.