Reflux Condensation Mediated Deposition of Co₃O₄ Nanosheets and ZnFe₂O₄ Nanoflakes Electrodes for Flexible Asymmetric Supercapacitor

A facile, scalable, economic and binder free reflux condensation mediated deposition strategy is reported for the direct growth of cobalt oxide (Co₃O₄) nanosheets (positive electrode) and zinc ferrite (ZnFe₂O₄) nanoflakes (negative electrode) on a highly conducting flexible stainless steel mesh (SSM, 300 mesh) for the first time. Both the electrodes show supercapbattery properties. Individually, Co₃O₄ nanosheet electrode exhibits a maximum specific capacitance of 2083 F g⁻¹ (specific charge capacity 312 mAh g⁻¹) at a high current density of 5 mA cm⁻² and also shows excellent cycle stability with 89% retention after 6000 cycles. On other hand, ZnFe₂O₄ nanoflakes electrode demonstrates a maximum specific capacitance of 923 F g⁻¹ (specific charge capacity 2100 mAh g⁻¹) at 5 mA cm⁻² current density with 94% capacitance retention after 9000 cycles. The electrodes are used for fabricating flexible solid state asymmetric supercapacitor. Interestingly, the fabricated device exhibits higher cycle stability up to 12,000 cycles with only 2% loss in capacitance retention and delivers a maximum energy density of 36 Wh kg⁻¹ even at a high power density of 8.8 kW kg⁻¹. This work reports novel alternative synthetic strategy which could be extended to other metal oxides providing new scientific insights and avenues.