2D sheet to 1D rod-like morphology regulated self-assembled ZnCo2O4 microstructures under mixed solvent conditions for battery-type supercapacitors

Abstract

This study examines the effects of the mixed solvent's characteristics on the nucleation and crystal growth processes and the surface morphologies of zinc cobaltite (ZnCo2O4; ZCO) microstructures. We discovered that the number of interaction sites in ZCO microstructures significantly increases when the solvent changes. This influences the material's high crystallinity, phase purity, morphology, and significantly influences its electrochemical conductivity. One with deionized (DI) water and ethanol mixed solvent and the other with DI water and ethylene glycol (EG) to produce mesoporous ZCO with rod-like and sheet-like microstructures, respectively. The ZCO-R delivered a high specific capacity of 468.5 C g−1 (130.13 mAh g−1) at a current density of 1 A g−1 compared to the ZCO-S (351 C g−1 / 97.5 mAh g−1). Additionally, the ZCO-R microstructures showed good rate performance (82% of its initial capacity) and cyclic stability (90% of capacity retention after 5000 cycles) due to their higher surface area and mesopore features. Hence, utilizing mixed solvent conditions to design morphology-controlled electrode materials is a promising approach to enhancing the electrochemical performance of battery-type supercapacitors.