Chemical Routes to Graphene-Based Flexible Electrodes for Electrochemical Energy Storage - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 422

Fig. 4 Charge-discharge profiles of a Li/graphene half-cell at a current rate of 50 mA g -1 ,
where the graphene component is either a graphene paper or b graphene powder. c Cycle
performance of a Li/graphene paper half-cell at three different current densities. d, e Schematic
illustration of Li-ion storage capability of graphene powder and graphene paper. Reprinted with
permission from [ 52 ]. Copyright (2010)
three-electrode half-cell system in aqueous 2 M KCl solution. At a scan rate of
10 mV s -1 , specific capacitances of 111, 105, 102, and 99 F g -1 were obtained
for the 25, 50, 75, and 100 nm films, respectively. Such values are relatively low
compared with many other forms of graphene.
Therefore, the application of graphene paper as flexible electrodes for energy
storage faces a key scientific and technical challenge. The performance of bulk
material strongly depends on the manner the individual sheets are arranged.
During the process of graphene nanosheets assembled into bulk form, the inter-
sheet van der Waals attractions inevitably cause aggregation or restacking of
individual graphene sheets. Consequently, many of the unique properties that
individual sheets possess, including high surface area and high ion conductivity