Chemical Routes to Graphene-Based Flexible Electrodes for Electrochemical Energy Storage - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 418

Fig. 1 Schematic illustration of conventional electrode and flexible electrode

stable CNT dispersions (which is essential to make CNT papers) have limited their
practical application as flexible electrodes.
Following the discoveries of fullerene and CNT in the earlier decades, the
successful fabrication of graphene has recently opened up an astonishing new field
in the research of materials science and technology [ 30 - 38 ]. Graphene is a two-
dimensional (2D) monolayer sheet of sp 2 -bonded carbon, which possesses unique
optical, electrical, mechanical, and electrochemical properties. The surface area of
graphene is calculated to be 2,630 m 2 g -1 ; graphene has high structural stability,
high electric conductivity, and easy to be functionalized with other molecules, and
all these characters are highly favorable for energy storage applications [ 39 - 41 ]. A
family of graphene-related materials, can all be commonly called ''graphene'' by
the research community, consists of structural or chemical derivatives of graphene.
These include double- and few-layer graphene and chemical reduced graphene
oxide (reduced GO, RGO) [ 42 ]. Inspired by their promising properties and enor-
mous potential applications, great attentions have rapidly been paid to explore new
significant scientific problems about graphene since its discovery. Actually,
graphene-based materials have the enormous potential to rival or even surpass the
performance of their CNT-based counterparts, given that cheap, large-scale pro-
duction and processing methods for high-quality graphene have already been
achieved [ 42 - 44 ].
Micromechanical cleavage from bulk graphite was firstly to be used to produce
graphene by Geim et al. [ 30 ], but the yield of this method is extremely low and the
process is uncontrollable. After that, various synthesis methods have been
developed, including epitaxial growth, chemical vapor deposition (CVD), etc.
[ 42 , 45 , 46 ]; however, these methods usually require high temperature, high-cost