Sequential electrodeposition of hierarchical ZIF-67@V2O5 on carbon cloth for binder-free supercapacitor electrodes

The performance of ZIF-67 as a supercapacitor electrode is hindered by the underutilisation of its internal structure and poor conductivity. This can be alleviated by designing a hierarchical system with a redox-active metal oxide material. In this work, a two-step electrodeposition approach was used sequentially to fabricate a ZIF-67@V 2 O 5 composite electrode on a carbon cloth substrate. V 2 O 5 provides more redox-active sites, thereby complementing the high porosity of ZIF-67 in the composite and yielding a high specific capacity of 146.7 mAh g −1 compared to 69.7 and 76.4 mAh g −1 for ZIF-67 and V 2 O 5 , respectively. The electrode was used to fabricate an asymmetric supercapacitor device, ZIF-67@V 2 O 5 // HH-AC, where activated carbon from recycled human hair served as the negative electrode. The device delivered a high specific energy of 58.8 Wh kg −1 at 1 A g −1 , corresponding to a specific power of 788.9 W kg −1 . The device also exhibited high stability, with coulombic efficiency and capacity retention of 99.4% and 87.4%, respectively, after 10000 GCD cycles at 5 A g −1 . This makes the proposed work suitable for incorporation into practical supercapacitor devices.