Carbon Nanomaterials for Flexible Energy Storage

Figures & data

Figure 1. (a) Photograph of a freestanding SWNT buckypaper prepared using the vacuum filtration method. (b) scanning electron microscopy (SEM) image of the buckypaper. (c) Image of SWNT paper strips that are bent around a curved surface. Adapted from Landi et al.25 (d) Cyclic voltammogram of buckypaper measured at 50 mV/s. (e) Galvanostatic charge–discharge curves measured at 5 mA. Adapted from Ci et al.26

Table 1  Typical results obtained from flexible electrodes assembled using pure carbon nanomaterial for supercapacitors or lithium ion batteries..

Material	Support	Fabrication technique	Capacity	Voltage/electrolyte	Remarks	Ref.
CNTs	–	Vacuum filtration	102 F/g @ 1 Hz	1 V in 38% H2SO4	Power density >8 kW/kg	32
CNTs	–	Direct CVD growth	51 F/g at 5 mA	6 M KOH	Measured using two electrodes setup	26
SWNTs	–	Spray coating	35 F/g at 0.75 A/g	3V in 1M LiClO4 (EC/DEC/DMC)	Measured using two electrodes setup energy density 43.7 Wh/kg, power density 197.3 kW/kg	33
MWNTs	–	Direct CVD growth and domino push method	81 F/g at 3 mA	1.2 V		30
Macroporous grapheme	–	‘Breath-figure’ method	103 F/g at 100 mV/s	0.8 V in 1 M H2SO4	Nitrogen doped graphene perform better	34
Reduced graphene oxide	–	Vacuum filtration and leavening strategy	110 F/g	0.8 V in 1 M H2SO4	measured using two electrodes setup	35
Reduced graphene oxide	–	Vacuum filtration with sacrificial polystyrene spacer	202 F/g at 1 A/g	1 V in 1 M Na2SO4		36
Reduced graphene paper	–	Vacuum filtration	215 F/g at 1.08 A/g	1 V in H2SO4	‘Wet’ graphene paper with low stacking power density 414 kW/kg	20
Graphene/MWNTs	–	Vacuum filtration	265 F/g at 0.1 A/g	1 V in 6 M KOH	16 wt% of CNTs work best	37
Carbon nanohorn and SWNTs	–	Vacuum drying using a dish	46 F/g at 0.1 A/g	2.5 V in 1 M Et4NBF4/PC	High power density (990 kW/kg, 396 kW/l) with 20% SWNT, 6.5% capacitance loss in 100 k cycles	18
AC/CNT	–	Vacuum filtration	267.6 F/g	1 V in 6 M KOH	Energy density 22.5 Wh/kg and 7.3 kW/kg 97.5% retention after 5,000 cycles	38
SWNT	Office paper	Direct casting SWNT ink	200 F/g	1.0 V in H2SO4	47 Wh/kg and 200 kW/kg in organic electrolyte (3V). 3% (in H2SO4) and 0.6% (organic) loss for 40 k cycles	39
Active carbon (YP17)	Woven cotton/ polyester fabrics	Screen printing	85–95 F/g @ 20 mV/s 0.43 F/cm^2 @ 5 mA/cm^2	1 M Na2SO4 or 2 M Li2SO4	Screen printing coat more active material than dip coating carbon coating: ∼ 4.9 mg/cm^2 8% drop after 10 k cycles	16

Figure 2. Schematic diagram of assembling compact-designed supercapacitor using freestanding flexible SWNT films. Reproduced with permission from Niu et al.33

Figure 3. Characterization of self-stacked, solvated graphene (SSG) film. (a,b) photographs of the as-formed flexible SSG film, (c) schematic of the cross-section of the SSG film, (d) CV curves obtained at 10 mV/s and (e) gravimetric capacitances measured at various charge–discharge currents. Reproduced from Yang et al.20

Figure 4. (a) digital and (b) SEM image of CNT and graphene composite electrode (16% CNTs), (c) specific capacitances of nanotube/graphene composites with different nanotube percentages measured within−1.0 to 0 V vs. saturated calomel electrode at 0.1 A/g in 6 M KOH. Adapted from Lu et al.37

Figure 5. (a) schematic illustration of a paper-based CNTs supercapacitor device, (b) charge–discharge curves in aqueous (lower curve) and nonaqueous (upper curve) electrolytes, (c) CNT weight normalized capacitance as a function of the charge–discharge current, (d) Ragone plot based on active mass, (e) device specific Ragone plot and (f) cycle life of the supercapacitor device. Adapted from Hu and Cui.69

Figure 6. Textile-based electrodes for flexible energy storage: (a) Dipping a piece of textile into aqueous CNT ink. (b) SEM image of CNT-coated textile. (c) SEM image of MnO₂–CNT–textile. (d) Specific capacitances at different scan rates for MnO₂–CNT–textile electrodes with different areal mass loadings of MnO₂. (e) SEM image of graphene-coated textile with uniform MnO₂ coating (scale bar 200 μ m). (f) SEM image of a typical microfiber with conformal coating of MnO₂ nanostructures (scale bar 5 μ m). Adapted from Yu et al.73

Table 2.  Examples of flexible electrodes enabled by carbon nanomaterials for supercapacitors reported in the literature.

Materials	Flexible support	Fabrication method	Active material loading	Results	Remarks	Ref.
MnO2	CNT-coated paper	Electrodeposition	0.38 mg/cm^2	540 F/g in 0.1 M Na2SO4 at 2 mV/s	20 Wh/kg and 1.5 kW/kg 5% drop for 1,000 cycles	86
MnO2	Graphene-coated textile	Dip coating + electrodeposition	∼ 0.4 mg/cm^2	315 F/g in 0.5 M Na2SO4		88
MnO2	Carbon cloth	Electrodeposition	0.2–1.2 mg/cm^2	425 F/g 230 mF/cm^2 in 0.1 M Na2SO4	∼6% loss during 1,000 cycles	90
MnO2	CNT-coated sponge	Electrodeposition	up to 12.8 mg/cm^2	∼ 1,000 F/g at 1 mV/s for MnO2<0.1 mg/cm^2∼ 200 F/g for MnO2>0.5 mg/cm^2	∼4% loss for 1,0000 cycles. 63 kW/kg and 31 Wh/kg	71
MnO2	CNT-coated textile	Electrodeposition	up to 8.3 mg/cm^2	2.8 F/cm^2 at 0.05 mV/s for 8.3 mg/cm^2 MnO2 185 F/g at 0.8 mg/cm^2 of MnO2	50% retention for 50,000 cycles 13 kW/kg and 5–20 Wh/kg	87
MnO2	Graphene-coated textile	Electrodeposition	NA	380 F/g at 0.1 mA/cm^2	20% and 45% capacitance increase with CNT and PEDOT wrapping, respectively	70
MnO2	Carbon nanoparticles coated carbon fabric	Electrodeposition	0.072–0.562 mg/cm^2	109 mF/cm^2 with 0.562 mg/cm^2 MnO2	15 min deposition lead to highest capacity (800 F/g)	91
MnO2	Zn2SnO4-coated carbon microfiber	Chemical plating with KMnO4	NA	621.6 F/g at 2 mV/s in 1 M Na2SO4	36.8 Wh/kg and 32 kW/kg. active material loading is low	92
Graphene/ MnO2	NA	Vacuum filtration	∼ 0.07 mg	256 F/g with 24% of MnO2 at 0.5 A/g	74% retention for 1,000 cycles	93
Graphene/ MnO2/CNTs	NA	Vacuum filtration	Up to 8.8 mg/cm^2	372 F/g at 10 mV/s, 130 F/cm^3	∼ 200 F/g at 8.8 mg/cm^2 strong film: tensile strength 48 MPa; Young's modulus: 2.3 GPa	14
MnO2	CNT buckypaper	Electrodeposition	∼20% of the whole electrode	516.2 F/g at 77 mA/g	88% retention for 3,000 cycles	94
MnO2	3-D graphene grown by CVD using Ni foam	Electrodeposition	Up to 9.2 mg/cm^2 92.9% of the	130 F/g and 1.42 F/cm^2	Load with upto 92.9% of MnO2 (entire electrode)	95
Co(OH)2	CNTs/textile	Hydrothermal reaction		11.22 F/cm^2 at 15 mA/cm^2	4% loss for 2,000 cycles	96
V2O5	CNTs buckypaper	Atomic layer deposition		Up to 1,550 F/g in 8 M LiCl	8% loss for 5,000 cycles	97
CuO	SWNT film	Natural drying	∼ 2 mg/cm^2	∼ 75.7 F/g in 1 M LiPF6/EC:DEC at 5 A/g	Slow decay for 1,000 cycles	98

Figure 7. (a) Schematic illustration of the structure of the graphene/MnO₂/CNT electrode; (b) SEM image and digital image (inserted) of the fabricated flexible electrode; (c) typical stress–strain curve for the flexible electrodes; (d) CV curves for a 30 μ m flexible electrode (2.02 mg/cm²) acquired at different scan rates and (e) comparison of the specific capacitance of the graphene/MnO₂/CNTs and the graphene/MnO₂ electrodes at different areal densities tested at 50 mV/s. Adapted from Cheng et al.14

Figure 8. (a) Schematic illustration of the assembly of a flexible asymmetric supercapacitor using the roll-up approach. The positive electrode is a flexible graphene/MnO₂/CNTs film and the negative electrode is AC/CNTs flexible film. (b) CV curves of a asymmetric supercapacitor acquired at increasing scan rates from 2 to 500 mV/s in 1 M Na₂SO₄, (c) galvanostatic charge–discharge curves obtained under different current densities and (d) comparison of the Ragone plots for supercapacitor devices assembled using different materials and/or different electrode structures. Adapted from Cheng et al.15

Landi B J Ganter M J Cress C D DiLeo R A Raffaelle R PCarbon nanotubes for lithium ion batteries. Energ Environ Sci. 2009;2(6):638–654 (doi:10.1039/b904116h)

 Web of Science ®Google Scholar

Ci L J Manikoth S M Li X S Vajtai R Ajayan P MUltrathick freestanding aligned carbon nanotube films. Adv Mater. 2007;19(20):3300–3303 (doi:10.1002/adma.200602974)

 Web of Science ®Google Scholar

Niu C M Sichel E K Hoch R Moy D Tennent HHigh power electrochemical capacitors based on carbon nanotube electrodes. Appl Phys Lett. 1997;70(11):1480–1482 (doi:10.1063/1.118568)

 Web of Science ®Google Scholar

Niu Z Q Zhou W Y Chen J Feng G X Li H Ma W J Li J Z Dong H B Ren Y Zhao D A Xie S SCompact-designed supercapacitors using free-standing single-walled carbon nanotube films. Energ Environ Sci. 2011;4(4):1440–1446 (doi:10.1039/c0ee00261e)

 Web of Science ®Google Scholar

Wang D Song P C Liu C H Wu W Fan S SHighly oriented carbon nanotube papers made of aligned carbon nanotubes. Nanotechnology. 2008;19(7):075609-1–6

 Google Scholar

Lee S H Kim H W Hwang J O Lee W J Kwon J Bielawski C W Ruoff R S Kim S OThree-dimensional self-assembly of graphene oxide platelets into mechanically flexible macroporous carbon films. Angew Chem Int Edit. 2010;49(52):10084–10088 (doi:10.1002/anie.201006240)

 PubMed Web of Science ®Google Scholar

Niu Z Q Chen J Hng H H Ma J Chen X DA leavening strategy to prepare reduced graphene oxide foams. Adv Mater. 2012;24(30):4144–4150 (doi:10.1002/adma.201200197)

 PubMed Web of Science ®Google Scholar

Choi B G Yang M Hong W H Choi J W Huh Y S3D Macroporous graphene frameworks for supercapacitors with high energy and power densities. Acs Nano. 2012;6(5):4020–4028 (doi:10.1021/nn3003345)

 PubMed Web of Science ®Google Scholar

Yang X W Zhu J W Qiu L Li DBioinspired effective prevention of restacking in multilayered graphene films: towards the next generation of high-performance supercapacitors. Adv Mater. 2011;23(25):2833–2838 (doi:10.1002/adma.201100261)

 PubMed Web of Science ®Google Scholar

Lu X J Dou H Gao B Yuan C Z Yang S D Hao L Shen L F Zhang X GA flexible graphene/multiwalled carbon nanotube film as a high performance electrode material for supercapacitors. Electrochim Acta. 2011;56(14):5115–5121 (doi:10.1016/j.electacta.2011.03.066)

 Web of Science ®Google Scholar

Izadi-Najafabadi A Yamada T Futaba D N Yudasaka M Takagi H Hatori H Iijima S Hata KHigh-power supercapacitor electrodes from single-walled carbon nanohorn/nanotube composite. Acs Nano. 2011;5(2):811–819 (doi:10.1021/nn1017457)

 PubMed Web of Science ®Google Scholar

Xu G H Zheng C Zhang Q Huang J Q Zhao M Q Nie J Q Wang X H Wei FBinder-free activated carbon/carbon nanotube paper electrodes for use in supercapacitors. Nano Res. 2011;4(9):870–881 (doi:10.1007/s12274-011-0143-8)

 Web of Science ®Google Scholar

Hu L B Choi J W Yang Y Jeong S La Mantia F Cui L F Cui YHighly conductive paper for energy-storage devices. P Natl Acad Sci USA. 2009;106(51):21490–21494 (doi:10.1073/pnas.0908858106)

 PubMed Web of Science ®Google Scholar

Jost K Perez C R McDonough J K Presser V Heon M Dion G Gogotsi YCarbon coated textiles for flexible energy storage. Energ Environ Sci. 2011;4(12):5060–5067 (doi:10.1039/c1ee02421c)

 Web of Science ®Google Scholar

Hu L B Cui YEnergy and environmental nanotechnology in conductive paper and textiles. Energ Environ Sci. 2012;5(4):6423–6435 (doi:10.1039/c2ee02414d)

 Web of Science ®Google Scholar

Yu G H Xie X Pan L J Bao Z N Cui YHybrid nanostructured materials for high-performance electrochemical capacitors. Nano Energy. 2012;2(2):213–234 (doi:10.1016/j.nanoen.2012.10.006)

 Web of Science ®Google Scholar

Kang Y J Kim B Chung H Kim WFabrication and characterization of flexible and high capacitance supercapacitors based on MnO2/CNT/papers. Synthetic Met. 2010;160(23-24):2510–2514

 Web of Science ®Google Scholar

Yu G H Hu L B Vosgueritchian M Wang H L Xie X McDonough J R Cui X Cui Y Bao Z NSolution-processed graphene/MnO2 nanostructured textiles for high-performance electrochemical capacitors. Nano Lett. 2011;11(7):2905–2911 (doi:10.1021/nl2013828)

 PubMed Web of Science ®Google Scholar

Chen Y C Hsu Y K Lin Y G Lin Y K Horng Y Y Chen L C Chen K HHighly flexible supercapacitors with manganese oxide nanosheet/carbon cloth electrode. Electrochim Acta. 2011;56(20):7124–7130 (doi:10.1016/j.electacta.2011.05.090)

 Web of Science ®Google Scholar

Chen W Rakhi R B Hu L B Xie X Cui Y Alshareef H NHigh-performance nanostructured supercapacitors on a sponge. Nano Lett. 2011;11(12):5165–5172 (doi:10.1021/nl2023433)

 PubMed Web of Science ®Google Scholar

Hu L B Chen W Xie X Liu N A Yang Y Wu H Yao YPasta M, Alshareef HN, Cui Y. Symmetrical MnO2-carbon nanotube-textile nanostructures for wearable pseudocapacitors with high mass loading. Acs Nano. 2011;5(11):8904–8913 (doi:10.1021/nn203085j)

 PubMed Web of Science ®Google Scholar

Yu G H Hu L B Liu N A Wang H L Vosgueritchian M Yang Y Cui Y Bao Z AEnhancing the supercapacitor performance of graphene/MnO2 nanostructured electrodes by conductive wrapping. Nano Lett. 2011;11(10):4438–4442 (doi:10.1021/nl2026635)

 PubMed Web of Science ®Google Scholar

Yuan L Y Lu X H Xiao X Zhai T Dai J J Zhang F C Hu B Wang X Gong L Chen J Hu C G Tong Y X Zhou J Wang Z LFlexible solid-state supercapacitors based on carbon nanoparticles/MnO2 nanorods hybrid structure. Acs Nano. 2012;6(1):656–661 (doi:10.1021/nn2041279)

 PubMed Web of Science ®Google Scholar

Bao L H Zang J F Li X DFlexible Zn2SnO4/MnO2 core/shell nanocable-carbon microfiber hybrid composites for high-performance supercapacitor electrodes. Nano Lett. 2011;11(3):1215–1220 (doi:10.1021/nl104205s)

 PubMed Web of Science ®Google Scholar

Li Z P Mi Y J Liu X H Liu S Yang S R Wang J QFlexible graphene/MnO2 composite papers for supercapacitor electrodes. J Mater Chem. 2011;21(38):14706–14711 (doi:10.1039/c1jm11941a)

 Web of Science ®Google Scholar

Cheng Y W Lu S T Zhang H B Varanasi C V Liu JSynergistic effects from graphene and carbon nanotubes enable flexible and robust electrodes for high-performance supercapacitors. Nano Lett. 2012;12(8):4206–4211 (doi:10.1021/nl301804c)

 PubMed Web of Science ®Google Scholar

Chou S L Wang J Z Chew S Y Liu H K Dou S XElectrodeposition of MnO2 nanowires on carbon nanotube paper as free-standing, flexible electrode for supercapacitors. Electrochem Commun. 2008;10(11):1724–1727 (doi:10.1016/j.elecom.2008.08.051)

 Web of Science ®Google Scholar

He Y Chen W Li X Zhang Z Fu J Zhao C Xie EFreestanding three-dimensional graphene/MnO2 composite networks as ultra light and flexible supercapacitor electrodes. Acs Nano. 2013;7(1):174–182 (doi:10.1021/nn304833s)

 PubMed Web of Science ®Google Scholar

Yuan C Z Hou L R Li D K Shen L F Zhang F Zhang X GSynthesis of flexible and porous cobalt hydroxide/conductive cotton textile sheet and its application in electrochemical capacitors. Electrochim Acta. 2011;56(19):6683–6687 (doi:10.1016/j.electacta.2011.05.050)

 Web of Science ®Google Scholar

Boukhalfa S Evanoff K Yushin GAtomic layer deposition of vanadium oxide on carbon nanotubes for high-power supercapacitor electrodes. Energ Environ Sci. 2012;5(5):6872–6879 (doi:10.1039/c2ee21110f)

 Web of Science ®Google Scholar

Zhang X J Shi W H Zhu J X Kharistal D J Zhao W Y Lalia B S Hng H H Yan Q YHigh-power and high-energy-density flexible pseudocapacitor electrodes made from porous CuO nanobelts and single-walled carbon nanotubes. Acs Nano. 2011;5(3):2013–2019 (doi:10.1021/nn1030719)

 PubMed Web of Science ®Google Scholar

Cheng Y W Zhang H B Lu S T Varanasiad C V Liu JFlexible asymmetric supercapacitors with high energy and high power density in aqueous electrolytes. Nanoscale. 2013;5(3):1067–1073 (doi:10.1039/c2nr33136e)

 PubMed Web of Science ®Google Scholar