Direct in situ assembly of bimetallic Co-Ni hydroxide/polyaniline-modified reduced graphene oxide nanocomposite for asymmetric flexible supercapacitor electrode

摘要

In the present work, a novel hybrid nanocomposite of bimetallic Co-Ni hydroxide and polyaniline-modified partially reduced graphene oxide (PRGO) was assembled via in situ growth route for supercapacitor application. A series of characterizations demonstrated that large quantities of bimetallic Co-Ni hydroxide nanosheets could longitudinally grow on the surface of PRGO substrate and intercross together, forming a hierarchical honeycomb-like microanostructure array. As-assembled CoNi(OH)_2/PRGO nanocomposite showed a much higher specific capacitance of 2760± 160 F g~(-1) at 1.0 Ag~(-1) in three-electrode measurements, in comparison with pristine bimetallic Co-Ni hydroxide, Co(OH)_2/PRGO, and Ni(OH)_2/PRGO reference electrodes, which originated from the synergy effect between component units and unique three-dimensional conductive porous framework of nanocomposite, thereby greatly promoting the redox processes of metal ions and facilitating the ion diffusion between the electrolyte and the electrode, as well as the electron transfer. Furthermore, after 1000 charge-discharge cycles, as-assembled nanocomposite electrode possessed good cycling stability, along with a high 93.2% retention level of capacitance at 10 A g~(-1). An asymmetric flexible all-solid-state supercapacitor device was equipped with poly (vinyl alcohol) film as the solid electrolyte, and as-assembled CoNi(OH)_2/PRGO as the positive electrode delivered a 74.84 ± 1.46 wh kg~(-1) energy density and a 374.34 ±0.15 w kg~(-1) power density at 0.5 Ag~(-1), indicating good supercapacitor performance for energy storage and applications in flexible and wearable electronics.