Hydro/solvothermally grown ZnS/MnO2-metal organic framework based hydrogel for all solid-state flexible supercapacitor

Abstract

Flexible hydrogel-based supercapacitor (SC) has amassed significant attention because of its outstanding mechanical endurance, which allows it to maintain stable electrochemical performance even after numerous bending cycles. This feature demonstrates its enormous potential for seamless integration into bendable and wearable electronic devices while maintaining energy storage efficiency. Hence, we report hydro/solvothermally grown bimetallic ZnS/MnO2 Metal-organic Framework (MOF) based hydrogel fabricated via freeze drying method for an all solid-state based SC. The successful formation of cubic structured ZnS/MnO2-MOF is confirmed from X-ray diffraction analysis. A detailed morphological analysis of ZnS/MnO2-MOF based hydrogel reveals uniform dispersion of ZnS/MnO2-MOF in the hydrogel with a randomly oriented nanosheets like structure consisting of pores on the surface. The electrochemical measurements of ZnS/MnO2-MOF hydrogel based all-solid state symmetric SC with PVA-KOH electrolyte illustrates 112 F/g of specific capacitance at 1.5 A/g. Additionally, it also results in 30.3 Wh/kg of energy density with corresponding power density of 1050 W/kg. Furthermore, the device shows an exceptional stability, as indicated by its ability to retain 63 % of its capacitance over 20,000 cycles. This outstanding performance of the device is ascribed to the high conductivity of bimetallic MOF, PVA-KOH solid electrolyte. The electrodes presented here provides a promising alternative to traditional SCs performances.