Facile synthesis of perovskite ZIF67 derivative using ammonia fluoride and comparison with post-treated ZIF67 derivatives on energy storage ability

Oxidation, carbonization, sulfurization and selenization are commonly used to enhance electrical con-ductivity and electroactivity of metal-organic frameworks. However, extra costs on time and money are required for post treatments. In this work, ammonium fluoride (NH4F) is incorporated in precursor so-lution for synthesizing perovskite ZIF67 derivatives as electroactive material. Novel particle-aggregated particle is obtained with largely reduced sizes and less grain boundaries. A highest specific capacitance (C-F) of 490.4 F/g is attained at 20 mV/s for the optimized ZIF67 derivative electrode prepared using NH4F and Co:Ni ratio of 2:1 (CoNi21-NH4F), while the untreated, oxidized, carbonized, sulfurized and selenized bimetallic ZIF67 electrodes synthesized without NH4F only show the smaller C-F values of 3.5, 363.9, 28.7, 85.9 and 103.2 F/g at 20 mV/s, respectively. Replacing 2-methylimidazole with F- in ZIF67 can improve electrical conductivity due to smaller size and higher electronegativity of F- than 2-methylimidazole. Largely enhanced C-F value for CoNi21-NH4F electrode strongly indicates success of improving energy stor-age via simply adding NH4F in precursor solution without post treatments. Maximum energy density of 22.7 Wh/kg at power density of 0.6 W/kg, C-F retention of 94% and Coulombic efficiency of 99% in 10.0 0 0 cycles charge/discharged process are obtained for supercapacitor with CoNi21-NH4F electrodes. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

In this study, perovskite ZIF67 derivatives were synthesized as electroactive material by incorporating ammonium fluoride in the precursor solution, resulting in reduced particle size and fewer grain boundaries for higher specific capacitance. The addition of NH4F successfully improved energy storage efficiency without the need for post treatment, enhancing the performance of supercapacitors.