Synthesis of sandwich-like porous nanostructure of Co3O4-rGO for flexible all-solid-state high-performance asymmetric supercapacitors

Abstract

A novkel hierarchical sandwich-like porous nanostructure of Co3O4-rGO composites have been synthesized by employing a solvothermal method. The Co3O4-rGO with hierarchical interconnected porous structures are composed of Co3O4 nanosheets with thickness of ∼4 nm, which are full of the numerous and hierarchical holes as short ion-diffusion channels. Moreover, the reduced graphene oxide (rGO) can play a significant role in the sandwich-like Co3O4-rGO composites due to its excellent electrical conductivity to improve the electron transport as “express channels”. The sandwich-like porous Co3O4-rGO composites exhibit opened hierarchical honeycomb-like structures filled with electrolyte ions as “ion-buffering reservoirs” and achieve a high specific capacitance value of 1260.6 F g−1 at a current density of 0.5 A g−1 in three electrode configuration. Furthermore, the asymmetric supercapacitors Co3O4-rGO//AC have been fabricated based on Co3O4-rGO as the positive electrode and AC as the negative electrode, exhibiting a high energy density of 38.8 Wh kg−1 at the power density of 400 W kg−1 and excellent long cycle life with 88.0% of the initial capacitance after 10,000 cycles. Moreover, the flexible all-solid-state asymmetric supercapacitors Co3O4-rGO//AC with PVA-KOH membrane as the electrolyte exhibit an excellent electric energy storage device for the potential applications.