University of Salerno

Graphene for supercapacitor application

Maria Sarno

Prof. Maria Sarno

Professor of Chemical Engineering

Director of NANO_MATES (Research Centre for NANOMAterials and nanoTEchnology at Salerno Univerity).

«Measurement of the quantum capacitance of graphene»

Xia J. et al., Nat Nanotechnol, 2009.

«Graphene-Based Supercapacitor with an Ultrahigh Energy Density»

Liu C. et al., J. NANO LETT, 2010.

«Ultrathin Planar Graphene Supercapacitor»

Yoo J. et al., NANO LETT, 2011.

«Electrochemical properties for high surface area and improved electrical conductivity of platium-embedded porous carbon nanofibers»

An G.-H. et al., J POWER SOURCES, 2012.

University of Salerno

Core – shell graphene coated FeCo

nanoparticles (GFeCo)

M. Sarno et al., Electrochemical Applications of Magnetic Core–Shell Graphene-Coated FeCo

Nanoparticles, Ind. Eng. Chem. Res., 2016, 55 (11), pp 3157–3166.

.

«Novel Cd-doped Co/C nanoparticles for Electrochemical Supercapacitors»

Barakat et al., MATER LETT, 2013.

«Silver nanoparticles decorated on a three-dimensional graphene scaffold for electrochemical applications»

Bello A. et al., J PHYS. CHEM. SOLIDS, 2014.

«Nitrogen-doped, FeNi alloy nanoparticle-decorated graphene as an efficient and electrode for electrochemical supercapacitors in acid

medium»

El-Deen et al., NANOSCALE RES LETT, 2015.

Graphene & Metal/Graphene composites for supercapacitors:

STATE OF ART

“Electrochemical Applications of Magnetic Core–Shell

Graphene-Coated FeCo Nanoparticles,

Maria Sarno et al., Ind. Eng. Chem.

Res., 2016”.

3 4 5 60

20

40

60

80

100

120

140

160

Co

un

ts

Diameter [nm]

GCMNPN2

Nanoparticles Results & DiscussionSYNTHESIS AND CHARACTERIZATION

1500 2000 2500

Inte

nsity (

a.u

.)

Wavenumber (cm-1)

D

G

2D

20 40 60 80

Inte

nsity (

a.u

.)

2Q°

(110)

(200) (211)

f

Core shell graphene coated FeCo nanoparticles have been prepared by a catalytic chemical vapor

deposition (CCVD) of methane on a FeCo catalyst in the channels of an alumina support.

X Ray Diffraction Pattern

Raman Spectrum

TEM images

1-2 graphene

layers

5 nm

2θθθθ °

Raman Shift cm-1

Galvanostatic Charge/Discharge Tests

C= 367,2 F/g at 0,9 A/g

University of Salerno

Graphene based Electrode Materials

M. Sarno et al., Supercritical CO2 processing to improve the electrochemical

properties of graphene oxide, J. of Supercritical Fluids 2016, 118, 119-127.

About SC-CO2 PROCESS FOR GRAPHENE-based SUPERCAPACITORS ELECTRODEs:

«Preparation of graphene oxide/polyaniline nanocomposite with assistance of supercritical carbon dioxide for supercapacitor

electrodes» G. Xu et al., Ind. Eng. Chem. Res. 2012

«Supercritical CO2 processing to improve the electrochemical properties of graphene oxide»

M. Sarno et al., J. of Supercritical Fluids 2016

SC-CO2 PROCESS FOR GRAPHENE-based SUPERCAPACITORS ELECTRODEs: STATE OF ART

Characterization

Mesoporous reduced graphene structures at different oxidation levels, have been obtained by SC-CO2 assisted process different durations

up to 24 h. It is investigated the effect of SC-CO2 processing on GO to produce a mesoporous reduced and exfoliated graphene structure

with high surface area and excellent electrochemical performance.

f

GO GO rGO-SC 24h

Typical contributions from• hydroxyl (C-OH),• ketonic species (C-O), • carboxyl (COOH), • sp2-hybridized C=C (in-plane vibrations), • epoxide (C-O-C) and • various C=O and C-O containing chemical species such as lactol, peroxide,

dioxolane, anhydride and cyclic ether

C=O

COOH

C-O-C

C-O-C

C=CC=C

OH of carboxyl group

Electrochemical characterization 1/2

0 100 200 300 400 500 6000,0

0,2

0,4

0,6

0,8

1,0 4 A/g

1,7 A/g

0,5 A/g

Vo

ltag

e /

V

Time / s

0 100 200 300 400 500 6000,0

0,2

0,4

0,6

0,8

1,0 4,5 A/g

1,7 A/g

1 A/g

Vo

ltag

e /

V

Time / s

ab

c

CYCLIC VOLTAMMETRY (a) GALVANOSTATIC CURVES (b, c)

rGO-SC 3h

rGO-SC 24h

At the same current density (1.7 A/g) the specific

capacitance of rGO-SC 24h (253 F/g) results about

three times larger than the one exhibited by rGO-

SC 3h (86 F/g).

0,0 0,2 0,4 0,6 0,8 1,0-30

-20

-10

0

10

20

30 GO

GO-SC3h

GO-SC24h

Cu

rren

t (A

/g)

Potential (V)

0 2 4 6 8 10 12 14 16

50

100

150

200

250

GO-SC 24 h

GO-SC 3h

Sp

ec

ific

Cap

acit

an

ce

/ F

g-1

Current density / Ag-10,0 5,0x10

21,0x10

31,5x10

32,0x10

32,5x10

30

20

40

60

80

100

GO-SC 24h

GO-SC 3h

Cap

acit

an

ce r

ete

nti

on

/ %

Cycles

Electrochemical characterization 2/2

Graphene based materials to realize:

a Novel Compact Supercapacitors

M. Sarno et al., SC-CO2-assisted process for a high energy density aerogel supercapacitor:

The effect of GO loading, Nanotechnology 2017, 28(20).

Electrodes with PVDF-HFP Poly(vinylidene fluoride-co-hexafluoropropylene) as electrode binder:

“ Supercapacitors from Activated Carbon Derived from Banana Fibers

Subramanian V, et al., J. Phys. Chem. C, 2007”.

Supercapacitors Devices with PVDF-HFP in gel polymer electrolyte:

“Electrochemical redox supercapacitors using PVdF-HFP based gel electrolytes and polypyrrole as conducting polymer

electrode Tripathi et al, Solid State Ionics, 2006 ”.

“Studies on redox supercapacitor using electrochemically synthesized polypyrrole as electrode material using blend

polymer gel electrolyte Tripathi et al., Indian J. Pure Appl. Phys, 2013”.

“High-performance flexible solid-state supercapacitors based on MnO2-decorated nanocarbon electrodes

Gao Y, et al., RSC Adv. 2013 “

“Ionic Liquid Directed Mesoporous Carbon Nanoflakes as an Effiencient Electrode material

Kong L and Chen W Sci. Rep. 2015”

Others Supercapacitors Devices :

«All-solid-state asymmetric supercapacitor based on reduced graphene oxide/carbon nanotube and carbon fiber

paper/polypyrrole electrodes Yang C, et al., J. Mater. Chem. A, 2014»

Compact Supercapcitor Devices: STATE OF ART

New Compact Supercapacitor Device

Acetone

GO

Sonication

Ethanol

Sonicated nanoparticles

PVDF-HFP

Acetone

<

Materials:

• GO prepared with Hummers’ method modified

• Poly-vinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) immersed in 1-

ethyl-3-methylimidazolium tetrafluoroborate, (EMIM BF4).

• PVDF-HFP_GO nanocomposite aerogel immersed in (EMIM BF4).

<

SEM images

PVDF_HFP

bd

c

Electrolyte Uptake (E u)

0 5 10 15 20

0

200

400

600

800

PVDF-HFP

PVDF-HFP_GO10

PVDF-HFP_GO30

PVDF-HFP_GO60

PVDF-HFP_GO90

Ele

ctr

oly

te u

pta

ke (

%)

Time (min)

0 130 260 390 520 650 780 910 1040 1170

Time (min)

0 20 40 60 80 100

80

82

84

86

Po

ros

ity

(%

)

GO amount in aerogel (w/w)

Porous volume

E u = (Ww − Wd)/ Wd × 100%

PVDF_HFP_GO30

PVDF_HFP_GO60 PVDF_HFP_GO90

a

b

c

Electrochemical Characterizations

2000 2100 2200 2300 2400 2500 2600 2700

Po

ten

tia

l (V

)

Time (sec)

0

2

-2

-2 -1 0 1 2-3x10

1

-2x101

-1x101

0

1x101

2x101

3x101

50 mV/sec

PVDF-HFP_GO10_SC

PVDF-HFP_GO60_SC

PVDF-HFP_GO90_SC

Cu

rren

t (A

/g)

Potential (V)-2 -1 0 1 2

-5x101

-4x101

-3x101

-2x101

-1x101

0

1x101

2x101

3x101

4x101

5x101

PVDF-HFP_GO60_SC

10 mV/sec

20 mV/sec

50 mV/sec

100 mV/sec

150 mV/sec

Cu

rre

nt

(A/g

)

Potential (V)

0 200 400 600 800

6 A/g

4 A/g

2 A/g

1 A/g

0,5 A/g

Po

ten

tial

(V)

Time (sec)

0

2

-2

0 2 4 60

10

20

30

40

50

60

Cap

ac

ita

nc

e (

F/g

)

Current density (A/g)

55 60 65 70 75 80 85 90 95 1000

Po

we

r d

en

sit

y (

W/k

g)

Energy density (Wh/kg)

0 2 4 6 8 100

20

40

60

80

100

En

erg

y d

en

sit

y (

Wh

/kg

)

Current density (A/g)

0,0 5,0x104

1,0x105

0

20

40

60

80

100

Cap

acit

an

ce r

ete

nti

on

/ %

Cycles

1 2 3 4 5 6 7 8 9 100

-2

-4

-6

-8

-10

Z''

(o

hm

)

Z' (ohm)

0 100 200 300 400 5000

-100

-200

-300

-400

-500

PVDF-HFP_GO60

PVDF-HFP_GO60 after 5*104 cycles

Z''

(o

hm

)

Z' (ohm)

CV Curves GDC Tests

Ragone Plot

Specific Capacitance Vs Current

density

Capacitance retentetion

Cyclic voltammogram (CV) of PVDF-HFP_GO10, PVDF-HFP_GO60 and PVDF-HFP_GO90 at 50 mV/s between -2 V and 2V

(a). CV of PVDF-HFP_GO60 at different scan rate between -2 V and 2V (b). Galvanostatic charge-discharge (GCD) curves

of PVDF-HFP_GO60 at different current density between -2 V and 2V (c). Specific capacitance at different current

density (d). Ragone plot. Insert showing energy density as a function of current density (e). Cycling life test of PVDF-

HFP_GO60 at 6A/g (f). Nyquist plot before and after GCD cycling (g).

a b

c

d

eg

f

C= 83 F/g

E=79.2 Wh/kg

P= 234 W/Kgat the current density of 0.5 A/g

In summary

• Controlled size, structure, and morphology core−shell 1−2 layer graphene-coated metallic

nanoparticles have been prepared by methane CCVD at atmospheric pressure. Electrochemical

tests show ideal capacity behavior, efficient energy storage, and excellent cycling stability. Such

high supercapacitor performance can be attributed to the high electric double-layer contribution

ensured by the micro-mesoporosity, with a high effective surface area and excellent electrical

transport of the conductive network.

• Feasibility of a SC-CO2 assisted process to reduce and exfoliate GO powders, obtaining porous and

three-dimensional architectures formed by curved graphene sheets.

• Supercapacitors have been assembles in a sandwich design formed by three porous layers.

Other Materials

ELECTRODES

� MoS2

� MoS2/FLG

� MoS2/MoO2/FLG

� Carbon nanotubes

� Flexible Supercapacitors with others nanomaterials, such as

� :• Fe3O4

• MoS2

• NiMoS• Ag/graphene

• RuO2/Os

• MoS2/Fe3O4• ….

Eng. Carmela Scudieri

Eng. Marcello Casa

Eng. Claudia Cirillo

Eng. Mariagrazia Iuliano

Eng. Waleed Abdalglil Mustafa

Eng. Eleonora Ponticorvo

Eng. Davide Scarpa

Eng. Domenico Spina

Eng. Alfonso Troisi

Eng. Gianluca Viscusi

Thank you for your attention

Acknowledgement

Prof. Paolo Ciambelli

Prof. Ernesto Reverchon and his research

group