Ultra-light Hierarchical Graphene Electrode for Binder-Free Supercapacitors and Lithium-Ion Battery Anodes

Abstract

A mild and environmental-friendly method is developed for fabricating a 3D interconnected graphene electrode with large-scale continuity. Such material has interlayer pores between reduced graphene oxide nanosheets and in-plane pores. Hence, a specific surface area up to 835 m2 g-1 and a high powder conductivity up to 400 S m-1 are achieved. For electrochemical applications, the interlayer pores can serve as ion-buffering reservoirs while in-plane ones act as channels for shortening the mass cross-plane diffusion length, reducing the ion response time, and prevent the interlayer restacking. As binder-free supercapacitor electrode, it delivers a specific capacitance up to 169 F g-1 with surface-normalized capacitance close to 21 μF cm-2 (intrinsic capacitance) and power density up to 7.5 kW kg-1, in 6 m KOH aqueous electrolyte. In the case of lithium-ion battery anode, it shows remarkable advantages in terms of the initiate reversible Coulombic efficiency (61.3%), high specific capacity (932 mAh g-1 at 100 mA g-1), and robust long-term retention (93.5% after 600 cycles at 2000 mAh g-1). An ultra-light hierarchical graphene electrode is prepared via a new and environmental-friendly activation method. It has a specific surface area up to 835 m2 g-1 and a powder conductivity of 400 S m-1. As binder-free electrode, it delivers a robust and high specific capacitance in supercapacitors and a capacity in lithium-ion anodes with a very high charge/discharge rate. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.