Hierarchical networks of redox-active reduced crumpled graphene oxide and functionalized few-walled carbon nanotubes for rapid electrochemical energy storage.

Byeongyong Lee,Hee Dong Jang,Tianyuan Liu,Thomas F Fuller,Kwangsup Eom,Seung Woo Lee,Suguru Noda,Chongmin Lee,Zhongming Chen

doi:10.1039/c6nr02013e

Abstract

Crumpled graphene is known to have a strong aggregation-resistive property due to its unique 3D morphology, providing a promising solution to prevent the restacking issue of graphene based electrode materials. Here, we demonstrate the utilization of redox-active oxygen functional groups on the partially reduced crumpled graphene oxide (r-CGO) for electrochemical energy storage applications. To effectively utilize the surface redox reactions of the functional groups, hierarchical networks of electrodes including r-CGO and functionalized few-walled carbon nanotubes (f-FWNTs) are assembled via a vacuum-filtration process, resulting in a 3D porous structure. These composite electrodes are employed as positive electrodes in Li-cells, delivering high gravimetric capacities of up to ∼170 mA h g(-1) with significantly enhanced rate-capability compared to the electrodes consisting of conventional 2D reduced graphene oxide and f-FWNTs. These results highlight the importance of microstructure design coupled with oxygen chemistry control, to maximize the surface redox reactions on functionalized graphene based electrodes.

Highlights

The rapid penetration of portable electronic devices and electric vehicles into our daily lives increasingly demands multi-functional electrochemical energy storage devices having high energy, high power and long-lasting lifetime.[1]
By correlating the microstructure and surface chemistry of the electrodes with their electrochemical performance, we reveal that the enhanced performance of the functionalized few-walled carbon nanotubes (f-FWNTs)/reduced crumpled graphene oxide (r-CGO) electrode can be attributed to the 3D hierarchical network structure, facilitating ion and electron transport for the effective utilization of the surface redox reactions between copious oxygen functional groups on the carbon supports and Li ions
This surface structural change is ascribed to the introduction of the oxygen functional groups on the surface of Scheme 1 Fabrication process of the f-FWNT/r-CGO electrode; the nebulized GO dispersion was crumpled in a furnace at a mild temperature of 300 °C, producing partially reduced crumpled graphene oxide (r-CGO) particles

Summary

Introduction

The rapid penetration of portable electronic devices and electric vehicles into our daily lives increasingly demands multi-functional electrochemical energy storage devices having high energy, high power and long-lasting lifetime.[1]. To effectively utilize the surface redox reactions of the functional groups, hierarchical networks of electrodes including r-CGO and functionalized few-walled carbon nanotubes (f-FWNTs) are assembled via a vacuum-filtration process, resulting in a 3D porous structure.

Results

Conclusion