Graphene and Polymer Composites for Supercapacitor Applications: a Review

Abstract

Supercapacitors, as one of the energy storage devices, exhibit ultrahigh capacitance, high power density, and long cycle. High specific surface area, mechanical and chemical stability, and low cost are often required for supercapacitor materials. Graphene, as a new emerging carbon material, has attracted a lot of attention in energy storage field due to its intrinsic properties. Polymers are often incorporated into graphene for a number of enhanced or new properties as supercapacitors. In this paper, different polymers which are used to form composite materials for supercapacitor applications are reviewed. The functions, strategies, and the enhanced properties of graphene and polymer composites are discussed. Finally, the recent development of graphene and polymers for flexible supercapacitors are also discussed.

Keywords: Composites; Flexible; Graphene; Polymers; Supercapacitors.

Fig. 1

a Schematics of vacuum filtration method to build graphene-containing supercapacitor electrode. b SEM image of graphene/PVDF on the nickel foam formed by vacuum filtration. Reprinted with permission from [10]. Copyright 2012 Elsevier

Fig. 2

a Pore size distribution of AC, AC-PTFE, and AC-PVDF electrodes. b Cyclic voltammograms (2 mV · s⁻¹) up to 0.8 V of AC/AC capacitors in 1 mol · L^-1 NaNO3 with PTFE and PVDF binders. Reprinted with permission from [19]. Copyright 2014 Elsevier

Fig. 3

CV (left) and Nyquist (right) plots of CMG material with KOH electrolyte (top), TEABF₄ in propylene carbonate (middle) and TEABF₄ in acetonitrile (bottom). Reprinted with permission from [24]. Copyright 2008 American Chemical Society

Fig. 4

Chemical structure p-doped PPy

Fig. 5

a SEM of pure PANI fibers (PANI-F). b SEM of GO and PANI composites with GO weight percentage of 10% (PAGO 10). c SEM of GO and PANI composites with GO weight percentage of 50% (PAGO 50). d SEM of GO and PANI composites with GO weight percentage of 80% (PAGO 80). e Cyclic voltammograms recorded in 2 M H₂SO₄ by using different composites coated with glassy carbon electrode as working electrode, a Pt sheet as counter electrode, and a AgCl/Ag electrode as reference electrode. The scan rate is 100 mV/s; f Charge/discharge cycling curves of different composite electrodes at a current density of 0.1 A/g. Reprinted with permission from [41]. Copyright 2010 American Chemical Society

Fig. 6

a A scheme illustrating the preparation process of graphene/PANI hybrid materials. b CV curves of graphene, PANI, GEOP-1, GEP-2, and GEP-3, at 1 mV s⁻¹ in 1 M H₂SO₄ in the potential range from −0.2 to 0.6 V. c Specific capacitance changes with different samples. Reprinted with permission from [44]. Copyright 2010 Royal Society of Chemistry

Fig. 7

SEM images of the surfaces pure PANI and PPy films at low (424 mC/cm²) and high (7.07 C/cm²) deposition charges (Q_dep) as indicated. Reprinted with permission from [46]. Copyright 2007 Elsevier

Fig. 8

SEM images of (a) pure RGO film (b) RGO, and PEDOT composites film. Reprinted with permission from [57]. Copyright 2013 Royal Society of Chemistry

Fig. 9

Cyclic voltammograms of (a) RGO-PEDOT (b) RGO-PPy, and c RGO-PANi cycle stability of PANi fibers, RGO-PANi, RGO-PEDOT, and (d) RGO-PPy during the long-term charge/discharge process. Reprinted with permission from [42]. Copyright 2012 American Chemical Society

Fig. 10

Ragone plot of graphene and CP composites supercapacitors in the summarized references listed in Table 1

Fig. 11

a Photographs of transparent thin-films of varying thickness on glass slides. b TEM image of graphene collected from dispersion before filtration. c SEM image of 100 nm graphene film on glass slide. Reprinted with permission from [76]. Copyright 2012 AIP Publishing LLC

Fig. 12

Schematic illustration of the preparation process of rGO-PEDOT/PSS films and the structure of assembled supercapacitor devices. Reprinted with permission from [84]. Copyright 2015 Nature Publishing Group

Fig. 13

a CVs of rGO-PEDOT/PSS during bending. Scan rate = 50 mV s⁻¹. b CVs of rGO-PEDOT/PSS after being subject to bending. c Long-term test of rGO-PEDOT/PSS under flat or 180 ° bended states at a current density of 1 A g⁻¹. d Flexible films coated with solid electrolyte spread out on an Au-coated membrane, e rolled design, and f the resulting device used to power a green light-emitting diode (LED). Reprinted with permission from [84]. Copyright 2015 Nature Publishing Group