Facile synthesis of nano-micro clusters of ZnCo 2 O 4 for supercapacitors

Supercapacitors and many other high-performance energy storage technologies have been the subject of intense research due to the rapidly growing interest in wearable electronics and electric cars. Self-assembled porous networks like nano-micro clusters of zinc cobaltite (ZnCo 2 O 4 , ZCO) have been synthesized using a simple, one-step and inexpensive reflux method for supercapacitor application. The effect of ionic surfactant (trisodium citrate, TSC) on the growth of the ZCO nanoparticles was studied. The structural, morphological, and electrochemical performance of the TSC-assisted ZCO electrodes were thoroughly tested. XRD studies reveal the spinel simple cubic (Fd3m) structure of ZCO clusters. RAMAN shows five active phonon (F 2g , F 2g , F 2g , E g , A 1g ) modes present in synthesized samples. BET provides a maximum 49.49 m 2 /g specific surface area for an optimistic sample. The porous structured TSC-assisted ZCO electrode enables electrochemical specific capacitance of 629 F/g (61.2 mAh/g) at a current density of 1 mA/cm 2 with a specific energy of 38.55 Wh/kg and power delivery of 450 W/kg. Furthermore, to check the practical suitability of the electrode, cyclic stability was studied, showing retention of 84.20% specific capacitance after 5000 consecutive CV cycles at 50 mV/s. Hence, the results indicated that the cost-effective and eco-friendly method of preparing nano-micro clusters like binary transition metal oxides provides a new direction for future research.