Inkjet-Printed Graphene for Flexible Micro-Supercapacitors

Woo LeeGeorge Meade Bond ProfessorStevens Institute of TechnologyHoboken, New Jersey

Linh T. Le and De Kong, StevensDr. Matthew Ervin, U.S. Army-ARLDr. Brian Fuchs and J. Zunino, U.S. Army-ARDEC

IEEE NANO ConferenceAugust 15-18, 2011, Portland, Oregon

www.jameshedberg.com

Graphene: A New 2D Nanomaterial for 3D Assembly

• Novel Properties– Electrically conductive– Optically transparent– Mechanically strong & conformal– High surface area– Chemically & electrochemically inert

• Diverse Production Methods– $50/kg anticipated in 3 years for

graphite-derived

• Inkjet-Printed Graphene Micropatterns– Electrodes for cheap, flexible energy

storage & generation devices

3D Assembly withInkjet-Printed

2D Graphene Nanosheets

Conventional Supercapacitor

Device Attributes Integration with flexible electronics Higher specific power (~100x

batteries) Rapid charge/discharge times Millions of charge/discharge cycles Stable at extreme temperatures

CurrentCollector

Separator

ActivatedCarbon

Electrode

ActivatedCarbon

Electrode

CurrentCollector

“+” Ions“−” Ions

Simon et al., Nature Materials,

2008

Kapton

Silver Current Collectors

Graphene Electrodes

HermeticSeal

Concept Flexible Micro-Supercapacitor

Electrolyte

a Yoshida et al, J. Power Sources, 1996

b Wu et al, Science, 2004c Reina et al, Nano Letters, 2008*Based on 74 µF/cm2 with KOH

Graphene: Ideal Electrode MaterialActivated Carbon

CarbonNanotubes

Graphene

Sheet Resistance

(Ω/)100-500a 10-100b 1000c

Surface Area(m2/g)

500(Actual)

1320(Theoretical)

2630(Theoretical)

Capacitance*(F/g)

120(Actual)

977(Theoretical)

1954(Theoretical)

Can we control the 3D assembly of conformal graphene nanosheets during printing and therefore their morphology for high surface area, ion transport, and electrical conductivity?

More Corrugation?

Inkjet-Printed Graphene Micropatterns

Process Attributes• 50 mm resolution • Net-shape with minimum

nanomaterial use, handling & waste generation• Scale-up & integration

readiness with commercial printers

5 ppm Carbon Nanotubesin Water

25 mm

Vertical Alignment of 20 Droplets

Le et al., Electrochemistry Communications, 13, 355 (2011)

www.dimatix.com

10 pL Droplet

16 Piezoelectric Nozzles

Graphene Oxide in Water as Scalable Ink

Reduction to Graphene•Thermal in hours• Photothermal in minutes

Dreyer el al., Chem. Soc. Rev., 2010, 39, 228-240

Hydrophilic Graphene Oxide

High-Throughput Droplet Generation

StableSuspension (0.5%) for Monthsw/o Surfactant

1 mm

Significant Size & Shape Variations in Graphene Oxide Ink

Other Characteristics– z potential: −20 mV– Viscosity: 1.06 mPa.s – Surface tension: 68 mN/m

1 to 5 Printed Graphene Layers

Ag4-Point Probes

Kapton

1 32 4

Glass Slide

Droplet Spacing

(mm)

Sheet Resistance

(M)

Trans-parency

(%)

20 0.3 78

30 3.1 85

40 5.5 93

Droplet Spacing Effect (5 Layers)

Inferior sheet resistance of photothermally reduced graphene oxide (1 M) to chemically reduced graphene oxide (1 k)

101 102 103 104 105 106 107 108 109101040

50

60

70

80

90

100

Tra

nspare

ncy (%

)

Sheet Resistance (/squr)

CVD-grown Graphene*

Inkjet-Printed Graphene*

Graphene reduced From Graphene Oxide

*Bonaccorso, Nature Photonics (2010)

20 mm

100 Printed Layers: Surface

1 mm

1 mm

100 Printed Layers: Cross-Section

Highly Porous Structure Develops during Printing 100 Layers

• Method– N2 isotherm adsorption

– BET surface area– BJH model for pore size

distribution analysis

• Bimodal distribution– 1.5-2.2 nm micropores– 11-36 nm mesopores

• Relatively narrow pore size ranges

Total Micropores Mesopores

Surface Area (m2/g)

282 140 142

Volume (cm3/g)

1.36 0.0846 1.27

0100

200

300

400

0

0.005

0.01

0.015

0.02

pore size [Å]

dV

(w)

[cm

3/Å

/g]

Capacitive Cyclic Voltammetric Behavior

Linear Galvanostatic Charge/Discharge

97% Capacitance Retention

Electrochemical Properties

1M H2SO4 Electrolyte

Teflon Blocks

Celgard Separator

Titanium Foil Current Collector

Inkjet-PrintedGraphene

Performance

Important Structural Features• Graphene alignment to electrical

current flow• Interconnected 1-10 nm porosity

for higher ion accessibility and conduction

Graphene(Powder Methods)

Printed Graphene

Capacitance(F/g)

~100[1]

~117[2] 132

Energy Density (Wh/kg)

4.1[2] 6.74

Power Density (kW/kg)

10[3] 2.19

[1] Stoller, 2008; [2] Vivekchand, 2008 ; [3] Wang, 2009 ; [4] Honda, Y. , 2007; [5] Zhang., 2011

0.1 1 10 1000.01

0.1

1

10

100

Specific Energy (Wh/kg)

Sp

ec

ific

Po

we

r (k

W/k

g)

Comparison to “Best” Electrodes

•Microwave for corrugated GO•KOH activation to

create 1-10 nm pores• 3100 m2/g [5]Aligned MWCNT [4]

Incompatible with Inkjet-

Printed Flexible Electronics

Effect of Droplet Spacing

2 mm

d1 & d2= 5 mm

2 mm

d1 & d2= 25 mm

1 mm

d1 & d2= 15 mm

d1

d2

More Corrugation?

Overall Device Level Challenges

Kapton

Silver Current Collectors

Graphene Electrodes

HermeticSeal

Electrolyte

Chemical & Electrochemical Compatibility– Electrolyte selection & testing– Ag current collector as

commercially available inkjet-printed material

– Packaging materials

Hermetic Packaging to Keep Electrolyte from Leaking & Drying– Heat-sealable pouch– Adhesive bonding via soft-

lithography

Graphene Electrode 3D Assembly

Ag printed & cured @130oC Printing Process– Initial surface effects– Ink optimization with controlled

size and shape distributions– High speed operation

Conclusions• Inkjet-printed 3D graphene

assembly demonstrated as high surface area supercapacitor electrodes with promising electrochemical properties.

• Inkjet-printing based on: (1) hydrophilic graphene oxide dispersed in water as a stable ink and (2) post thermal or photothermal reduction.

• Flexible micro-supercapacitor device being developed with printed graphene as micropatternable electrodes.

Linh Le

De Kong

Acknowledgements• “Integrated Flexible Energetics

and Electronics,” U.S. Army - ARDEC• Tim Luong, Fujifilm-Dimatix

Backup

Hon et al., CIRP Annals, 2008

Commercial Printers

www.dimatix.com

16 Microfabricated Piezoelectric Nozzles

Cartridge

1 or 10 pL Droplets

Sono-Plot

HP-ASUFlexibleElectronics

Reference: FlexTech Alliance (2009)

• Roll-to-Roll Printing

• Evaporative Assembly of Nanomaterials under Microfluidic Control

Silicon Electronics

Flexible Electronics

Transistors Billions Thousands

Feature Size 10-2 mm 10 mm

Cost of Fab $2-3B/Fab $10-200M/Fab

200 nm

Inkjet-PrintedSilver Conductor

NanoscaleMaterials

Microfluidic Tools

Woo Lee’s GroupTransformative

Biomedical & Energy Devices

Partnerships forTranslation and Impact

1 mm

200 mm

Nanomaterial Assembly

in vitro 3D Bone Tissue