Recent work on the EFG with various

Recent work on the EFG with various edge groups (e.g. H, COOH and SO3H) by effective and eco-friendly ball milling of graphite (Fig. 4d) provides an effective means for the development of functionalized graphene materials with tailor-made chemical structures and electronic properties attractive for multifunctional applications [65], including large-area transparent and conducting electrodes for electronics and metal-free catalysts for oxygen reduction reaction in fuel cells [66]. Although EFGs have hardly been exploited for energy-storage application, the use of EFGs, having abundant active sites at the edge and perfect conjugation (conductivity) on its basal plane, as the electrode materials could lead to high-performance supercapacitors with a high rate capability. Through controllable self-assembling, EFGs should also facilitate the formation of hierarchically structured electrodes in supercapacitors for specific applications.