A novel zinc sulfide impregnated carbon composite derived from Zeolitic Imidazolate Framework-8 for sodium-ion hybrid solid-state flexible capacitor

The pyrolysis of metal-organic frameworks (MOFs) is an easy approach to prepare metal oxides as well as nanoporous carbon with high specific surface area. In the present work, for the first time, ZIF-8 (zeolitic imidazolate framework-8) has been pyrolyzed under different conditions to derive two products, i.e., highly porous carbon (C) and zinc sulfide (ZnS) infused carbon (ZnS@C). These two materials, i.e., nanoporous C and ZnS@C have been investigated as a negative and a positive electrode, respectively for potential application in a hybrid asymmetrical solid-state supercapacitor device (HASD). The controlled pyrolysis approach for the preparation of ZnS@C has yielded uniformly distributed ZnS nanoparticles inside the carbon structure. A 1.8 V HASD has been assembled, which delivers an excellent energy density of 38.3 Wh/kg (power density of 0.92 kW/kg) along with the much desirable feature of cyclic stability. The proposed selection of materials as electrodes is promising to develop futuristic hybrid capacitors.