Construction of MnO2 Encapsulated ZIF-8 Composites as Electrode Material for Asymmetric Supercapacitor: Improved Electrochemical Performance via Redox Additive Electrolytes
摘要
Zeolitic imidazolate framework-8 (ZIF-8) and their composites are promising materials for energy storage applications due to their tunable structure, porosity, and large surface area. In this work, novel MnO2@ZIF-8 nanocomposites have been synthesized and, their electrochemical properties have been investigated. In XPS analysis, the doublet at 641.54/653.19 eV matches MnO2, while the doublets at 641.41/653.4, 643.41/656.19, and 645.92/658.21 eV correspond to Mn2+, Mn3+, and Mn4+, respectively. The surface area of MnO2@ZIF-8 is 563.511 m2/g with the pore volume of 0.1482 cc/g . The electrochemical performance of composites has been examined in 3 M KOH and redox additive electrolyte (RAE), respectively. As a result, the MnO2@ZIF-8 electrode displays a specific capacitance of 549.22 F g−1 at a current density of 5 A g−1 in RAE. Thecapacitance retention have kept 77.69% of the initial capacitance after 10,000 cycles and its synergistic interaction with the redox-additive electrolyte to further improve specific capacitive performance through highly reversible Mn2+/Mn3+ redox reactions and enhanced overall electrochemical performance. The nanocomposite electrode has a highly reversible Mn(II)/Mn(III) redox reaction with a redox additive electrolyte. Based on the above observations, the prepared composite material demonstrates considerable potential for energy-efficient applications in sustainable and clean energy systems