High-performance asymmetric supercapacitors of advanced double ion-buffering reservoirs based on battery-type hierarchical flower-like Co3O4-GC microspheres and 3D holey graphene aerogels

We have prepared 2D macromolecular brushes of G > N-PEGm nanosheets and CNT > N-PEGm from the Graphene and CNTs with methoxypolyethylene glycol (mPEG) via Nitrene Chemistry, respectively. Owing to a typical solvothermal method, the hierarchical flower-like spheres of Co3O4-G > N-PEGm-CNT > N-PEGm (Co3O4-GC) ternary composites have been synthetized, which present honeycomb-like structures as ion buffering reservoir and substantial ion-diffusion channels in the ultrathin 2-4 nm Co3O4 nanosheets. And as typical battery-type positive electrode materials, a high capacity of Co3O4-GC can be calculated up to 173.3 mAh g(-1) at 0.5 A g(-1) (the specific capacitance can be achieved to 1783 F g(-1)). On the other hand, 3D holey reduced graphene oxide and carboxylic CNT aerogels (HRGO-CNTc, denoted as HRGC) formed with holey graphene and the acid-modified CNTc are summarized as 282.3 Fg(-1) (78.4 mAh g(-1)) at 0.5 A g(-1), demonstrating excellent long cycling performance. The advanced double ion-buffering reservoirs of asymmetric supercapacitors Co3O4-GC//3D HRGC energy devices are further fabricated based on advanced battery-type Co3O4-GC as positive electrode and 3D HRGC aerogels as negative electrode, meanwhile the asymmetric devices with excellent electrochemical performance also exhibit 42.6 Wh kg(-1) at power densities of 775 W kg(-1) and 81.1% capacitance maintained after 10,0 0 0 cycles for energy-storage and energy-conversion potential application. (c) 2020 Elsevier Ltd. All rights reserved.

Automated summary

2D macromolecular brushes were prepared from graphene and CNTs, and hierarchical flower-like spheres of Co3O4-G > N-PEGm-CNT > N-PEGm ternary composites were successfully synthetized. The Co3O4-GC composites exhibited honeycomb-like structures with substantial ion-diffusion channels and high capacity.