Boosting the energy density of highly efficient flexible hybrid supercapacitors via selective integration of hierarchical nanostructured energy materials

A preeminent technique to boost the energy density of flexible hybrid supercapacitor (FHSCs) is to develop unique, extremely efficient, and smart positive and negative current collectors with hierarchical nanoarchitectures integration of various electroactive materials. Herein, we present a facile and flexible approach towards the synthesis of selective integration of hierarchical leaflet-like Ni(OH)₂ nanoflake arrays with ZnO–ZnCo₂O₄ nanowire arrays (Ni(OH)₂ NFAs@ZnO–ZnCo₂O₄ NWAs) on Ni foam mesh for ultrahigh-capability electrodes. The innovative strategy results in hierarchical architecture with highly altered electronic nanostructure, which not only enhances the specific surface area but also provides ultrafast transportations between ions and electrons. Under electrochemical conditions, the battery-type materials of the hierarchical leaflet-like Ni(OH)₂ NFAs@ZnO–ZnCo₂O₄ NWAs electrodes show ultrahigh specific capacity of 237.7 mA h g⁻¹ at 2 A g⁻¹; this value is 2.16, 1.53 and 1.30 times than those of ZnO–ZnCo₂O₄ NWAs, CoO NFAs@ZnO–ZnCo₂O₄ NWAs and ZnO NFAs@ZnO–ZnCo₂O₄ NWAs electrodes, respectively. Most importantly, in flexible assembly, the Ni(OH)₂ NFAs@ZnO–ZnCo₂O₄ NWAs//Fe₂O₃@NF NFAs FHSCs device delivers an ultrahigh energy density of 80.10 W h kg⁻¹ a superior life-spam performance, and retention around 98.2% of initial capacity after 5000 cycles. The new innovative strategy could be very promising for future flexible electronics devices.