Graphene capacitance

The N-doped carbons with a nanotube backbone combine a moderate presence of micropores with the extraordinary effect of nitrogen that gives pseudocapacitance phenomena. The capacitance of the PAN/CNts composite (ca. 100 F/g) definitively exceeds the capacitance of the single components (5-20 F/g). The nitrogen functionalities, with electron donor properties, incorporated into the graphene rings have a great importance in the exceptional capacitance behavior. 

Zhang, D., et al., Enhanced capacitive deionization performance of graphene/carbon nanotube composites. Journal of Materials Chemistry, 2012. 22(29) p. 14696-14704. 

Graphene functionalized with polyaniline can be used as a high-performance flexible electrode. The gravimetric and volumetric capacitances of the hybrid reach 233 F g1 and 135 F cm 3 respectively, more than those of graphene paper (147 Fg-1 and 64 F cm 3) [90],... 

Fig. 27 Supercapacitor study using graphene electrodes (5 mg each), (a) Cyclic voltammogram of chemical vapor deposited graphene (CG) nanodiamond derived graphene (NG) and exfoliated graphene (EG), (b) Evolution of specific capacitance vs scan rate. (Reprinted with permission Ifom [243])...

Fig. 7 (a) Cyclic voltammograms of the different graphene electrodes (at a scan rate of 20 mV s 1) for lOOmM K4Fe(CN)6 in 1 M KCI and (b) voltammetry characteristics of a capacitor built from an EG electrode at a scan rate of 100 mV s 1 using PYR14TFSI. Inset shows the specific capacitance as a function of scan rate. 

Lu, X., Zhang, E, Dou, H.,Yuan, C.,Yang, S., Hao, L., Shen, L., Zhang, L., Zhang, X., 2012. Preparation and electrochemical capacitance of hierarchical graphene/polypyrrole/carbon nanotube ternary composites. Electrochim. Acta 69,160-166. 

It was reported that the synthesis of mesoporous PANI film on ultrathin graphene nanosheets is favorable for high-performance supercapacitors (Wang et al., 2014b). Due to the mesoporous structure of the composite electrode, it dramatically improved the specific capacitance, rate capability, and cyclic stability in comparison to the bare PANI. The composite displayed specific capacitance of 749 F g at 0.5 A g in 1 M H2SO4 electrolyte and retained by 73% at 5.0 A g i, much higher than 315 F g at 0.5 A g i and 39% retention at 5.0 A g for the pristine PANI. In addition, the composite can maintain 88% of... 

Mini, PA., Balakrishnan, A., Nalr, S.V, Subramanian, K.R., 2011. Highly super capacitive electrodes made of graphene/polyfpyrrole). Chem. Commun. 47,5753-5755. 

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