Carbon Decorated MOF for Low-Cost Aqueous Al-Ion Supercapacitors: Effect of Redox Additives

The performance enhancement of ZIF-67 based Al-ion supercapacitors using conductive additives is presented. By using the simple co-precipitation technique, the porous ZIF-67 and composites of ZIF-67 with two distinct forms of carbon rGO and CNS were synthesized. Physiochemical characterizations like XRD, BET, FTIR, etc., were performed to confirm the successful synthesis of ZIF-67 and its composites. The electrochemical measurements were performed in the three-electrode configuration using 0.5 M AlCl 3 electrolyte. Out of all, the composite of ZIF-67 with rGO (ZIF-67_rGO) outperformed all other materials because of its larger specific surface area and enhanced electrical conductivity. Further, the electrolyte modification was performed in 6 mM KFCN as a redox additive for ZIF-67_rGO composite. Here, the specific capacitance of ZIF-67_rGO composite enhanced from 245 F g -1 to 346 Fg -1 at 1 A g −1 current density. Using the redox additive, we observe an increment of almost 41% in ZIF-67_rGO composite than its pristine counterpart. The composite also delivered good cycling stability with excellent coulombic efficiency of 89% and 95% after 1000 cycles, at 5 A g -1 current density, respectively.