N-functionalization and defect engineering in ZnCo2O4 nanosheets boosted the performance of Zn-ion hybrid supercapacitor
Xiaofeng Zhang, Muhammad Sufyan Javed, Syed Shoaib Ahmad Shah, Fahim Ahmed, Iftikhar Hussain, Fatimah Mohammed A. Alzahrani, Norah Salem Alsaiari, Sayed M. Eldin, Mohd Zahid Ansari, Weihua Han
Abstract
Transition-metal oxides are a class of promising pseudocapacitive materials for high energy density supercapacitors, while their low intrinsic conductivity and remarkable volume expansion deteriorate the electrochemical properties. Herein, we develop a binder-free mesoporous architecture supported on a carbon cloth (CC) substrate based on the nitrogen (N)-doped and oxygen vacancy (Ov)-rich zinc cobalt oxide nanosheets (denoted by N-Ov-ZCO@CC). Because of the instructive synergy of doping, defect, and surface engineering achieved by N-functionalization, the N-Ov-ZCO@CC exhibits significantly enhanced electrochemical properties. The N-Ov-ZCO@CC single electrode exhibited a high capacitance of 2166.4 F/g at 1 A/g with superb rate-capability (91.2% at 20 A/g) and superior cycling stability of 98.99% up to 5,000 cycles. In addition, a zinc-ion hybrid supercapacitor (ZHSC) device, assembled with the N-Ov-ZCO@CC as the cathode and Zn-foil as the anode, shows a high energy density of 95.35 Wh/kg at the power density of 10,008 W/kg, superior to most state-of-the-art ZHSCs. This work provides an effective strategy for constructing multifunctional electrochemical energy materials for ZHSCs.