Metal-organic frameworks (MOFs) as inorganic fillers in solid-state electrolytes for supercapacitor applications

Three distinct MOFs; HKUST-1, MOF-5 and UiO-66 each having unique structural characteristics were synthesized and their molecular structures are confirmed using FT-IR, PXRD and FESEM techniques. Continuing the experiments, to observe their potential as inorganic fillers, conductivity of the MOFs was measured by EIS and results indicate that UiO-66 exhibits the highest conductivity value, with a value of 2.32 × 10 −5 Scm −1 . Different salt percentage were added into the MOFs to see the effects of moving ions and results obtained show that different MOFs display varied conductivity values that consistently increase upon the addition of salt. Each MOF demonstrated a unique optimized percentage of salt was determined to be 60 %, 40 % and 10 % specifically for HKUST-1, MOF-5 and UiO-66 respectively. The highest conductivity value was observed for UiO-66 with 10 % NaCl, for HKUST-1 and MOF-5 with 60 % and 40 % NaCl conductivity reaching up to 9.61 × 10 −6 and 1.43 × 10 −7 Scm −1 . CV conducted on the MOFs and their salt systems showing leaf-shaped cyclic voltammogram demonstrates promising EDLC behaviour. Dielectric calculations were performed and agree well with the experimental values.