Supercapacitors: key systems for

energy sustainability

Dipartimento di Chimica “Giacomo Ciamician”

http://www.ciam.unibo.it/leme

LEME - Laboratory of Electrochemistry of Materials for Energetics

francesca.soavi@unibo.it

Francesca Soavi

23/05/2017 OCEM

Laboratorio di Elettrochimica

dei Materiali per l’Energetica

ALMA MATER STUDIORUM

UNIVERSITA’ DI BOLOGNA 1088 - STUDIUM IN BOLOGNA

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1

69th ISE Annual Meeting

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Abstract submission

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Topics: Batteries, Fuel cells, Supercapacitors: materials, processes and systems

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Symposium 8 Supercapacitors: from double-layer electrochemical capacitors to faradaic-based high power systems

Department of Chemistry

“Giacomo Ciamician”

The first chair in Chemistry in Italy was established

in Bologna in 1737

Research Areas

Analytical Sciences

Computational Chemistry

Electrochemistry

Molecular Spectroscopy

Organic Synthesis

Photochemistry and Supramolecular Chemistry

Physical Organic Chemistry

Polymers and Materials

Structural and Solid State Chemistry

http://www.chimica.unibo.it/it

Staff: 17 Full Professors, 36 Associate Professors,

25 Assistant Professors , 45 Post-doc (Assegnisti)

31 administrative assistants and technicians

Electrochemistry of Molecular and

Functional Materials (Prof. F. Paolucci)

Electrochemistry of Materials for

Energetics - LEME (Prof. C. Arbizzani)

10

LEME- Laboratory of Electrochemistry

of Materials for Energetics

https://site.unibo.it/leme/en

Systems

Lithium Batteries

Supercapacitors

Fuel cells

Materials

Nanostructured

electrodes

Novel electrolytes

Electrospun

membranes

Applications

Electric vehicles

Renewable energy

storage

Portable device

DAAD

Prof. Catia Arbizzani

Dr. Francesca Soavi

Electrochemical energy storage/conversion

High efficiency

renewable energy storage & electric grid quality

700

600

500

400

300

200

100

0

Mill

ion to

nn

es o

il equiv

ale

nt

1990 2000 2010 2020 2030

Global Renewable Energy

Consumption

BP Energy Outlook to 2030

Battery, Supercapacitors, Fuel cells

Italy 7 GW storage installed (mainly hydro) 75 MW Li-ion, Na-Ni, Flow batteries and

Supercaps (pilot plants -250 mln €)

World

170 GW storage installed

http://www.energystrategy.it

Electrochemical energy storage/conversion

High efficiency

electric/hybrid vehicles Hybrid electric vehicles sold per year

M units worldwide

Battery, Supercapacitors, Fuel cells

automotive accounts for > 20% of CO2

EU emissions

2016

518000

BEV &PHEV Battery cost

Vehicle

Models

http://www.energystrategy.it

90 kWh

350 kW

8

Battery, Supercapacitors, Fuel cells

Electrochemical energy storage/conversion

High efficiency

Maintenance-free implantable biosensors

Remote and mobile environmental sensors

Nanorobotics,

Portable and wearable personal electronics

ICT

Self-powered and autonomous systems

www.iea.org.

C. Pangy C. Lee, K.-Y. Suh, J. APPL. POLYM. SCI. 2013, DOI: 10.1002/APP.39461I

Global energy demand of network-enabled devices

140 TWh by 2025 (6% of current total global electricity consumption.)

≲ Wh

mW

DOUBLE-LAYER ELECTROCHEMICAL CAPACITOR

EDLC capacitance

CEDLC =(C1-1+ C2

-1)-1

capacitance

C = kA/d =Q/V

k dielectric permettivity.

A plate area

d plate distance

EDLC Supercapacitors

2

- + dielectric

d

plane capacitor

-

-

-

-

-

-

-

+

+

+

+

+

+

+

pF to µF

charged/discharged by electrostatic processes

plates

separator

High surface area carbon electrode/electrolyte interfaces

Electrolyte ions

• High Electrode area A 1000-2000 m2 g-1

• Small “Plate distance” d double layer thickness (10-10 m)

Supercapacitance up to 1 F and 100-200 F/g

B.E. Conway, Electrochemical Supercapacitors, KA/PP, New York 1999

EDLC Supercapacitors

3 M. Winter, R.J. Brodd, Chem. Rev., 2004, Vol. 104, No. 10 4247

Upon charge EDLC voltage linearly

increases up to a Vmax limit set by the

electrochemical stability of the

electrolyte.

B.E. Conway, Electrochemical Supercapacitors, KA/PP, New York 1999

Electrolyte Electrode

capacitance F/g

Vmax

V

Emax

Wh/kg

Pmax

kW/kg

Aqueous

H2SO4, KOH

150-200 1.0-1.5 1-2 1

Organic

Et4NBF4 -PC/ACN

80-100 2.5-2.7 5-6 6

…Ionic liquids for Vmax 3,0-3.5 V

Energy E= ⎰V dQ

Emax = 1/2 CEDLCVmax2

Power Pmax = Vmax2 / 4ESR

Capacitance CEDLC = Q/V

Energy storage by FAST and highly REVERSIBLE electrostatic

surface processes

Higher Energy than Capacitors but

lower Power

Higher Power than batteries but lower

Energy

Longer Cycle life than batteries

Higher safety than batteries

EDLC Supercapacitors

3 M. Winter, R.J. Brodd, Chem. Rev., 2004, Vol. 104, No. 10 4247 C. Arbizzani, F. Soavi, Enciclopedia Treccani, IX Appendice (2015)

Specific

Pow

er

(W/k

g)

Specific Energy (Wh/kg)

Ragone Plot

Other Types of Supercapacitors (SCs)

• Pseudo-supercapacitors with battery-like electrodes (electronically

conducting polymers and metal oxides) that are charged/discharged by fast

and reversible redox processes.

• Hybrid supercapacitors with positive and negative electrode materials of

different nature that are charged/discharged via different electrostatic and

faradic modes.

Increasing C and V increases specific energy of supercacitors

Emax = 1/2 CV2

4

SC Applications

6 J.R. Miller and A. F. Burke The Electrochemical Society Interface, Spring 2008, 53

H. Chen et al. / Progress in Natural Science 19 (2009) 291

Regenerative Braking, short-term energy storage or burst-mode power delivery

High power – Rapid charge/discharge cycles

power tools

memory backup

Electric grid quality

High frequency

Peak shaving

Load levelling

SC Applications and novel frontiers

LIB EDLC

$/Wh 1-2 10-20

$/kW 75-150 25-50

6 J.R. Miller and A. F. Burke The Electrochemical Society Interface, Spring 2008, 53

X. Luo et al. Applied Energy 137 (2015) 511

• High power lithium-ion batteries (LIBs) may compete with

organic EDLCs

• While EDLCs materials are cheaper than LIB’s, the EDLC

cost is higher when normalized to energy

• EDLC are safer and more stable than batteries

Cell prototype 3.7V - 340 F

…towards novel SC frontiers

7

Self-powered and autonomous systems

energy-generating

cloth and shoes IMC wearable wireless

electroencephalograpy

system with hybrid power

supply

(PV+thermoelectric)

from ambient: PV, thermoelectrics, mechanical

vibration, piezoelectric, enzimatic and microbial

fuel cells … but low power and voltage output

batteries or supercapacitors for power quality,

regulation and to boost power output

….towards sustanibility, integration and

miniaturization

sensors, transceivers

…but high power and voltage operation

Z. L. Wang, Adv. Mater., 2012, 24, 280–285., M. Beidaghi, Y. Gogotsi, Energy Environ. Sci., 2014, 867–884 9

Self-powered and autonomous systems Maintenance-free remote and mobile environmental sensors, nanorobotics,

and portable and wearable personal electronics need autonomy.

ENERGY

HARVESTER

ENERGY

STORAGE

FUNCTION

DEVICE

...towards low-power integrated devices

Why supercapacitors (SC) ?

SCs outperform batteries in applications having high peak-to-average power

demand

SCs feature superior cycling stability, which is of paramount importance for

applications, like sensors, where repeated power peaks are required.

Electrode components (carbons, polymers) of SCs

are easily processable for in-plane, flexible

architectures.

10

Supercapacitors are key components of low-power and autonomous

systems

They can store the energy harvested from the environment and provide

power pulses

M. F. El-Kady and R. B. Kaner, Nat. Commun., 2013, 4, 1475.

Why supercapacitors (SC)?

High “electric response flexibility” of SCs:

• EDLC charge takes place at any voltage > 0 V. The voltage linearly

increases up to a limit set by the electrochemical stability of the

electrolyte.

• Battery charge takes place at the voltage set by the electrode processes

Only the EDLC stores the energy.

charge discharge

Voltage

time

battery

Energy

harvester

voltage

output

The energy havested is stored by

both EDLC and the battery

charge discharge

Voltage

time

battery Energy

harvester

voltage

output

EDLCs can be directly combined with a wide range of energy harvesters

including those operating at low voltage

11

Why supercapacitors (SC) ?

Many capacitive/pseudocapacitive electrode materials used in SCs exhibit

strategic additional properties that can be exploited for specific applications,

along with their capability of reversibly storing charge and, thus, energy

• High surface area carbons : catalysts or catalyst supports for various types

of fuel cells

• Pseudocapacitive polymers : mechanical, optical and electronic properties

that are exploited in actuators, electrochromic devices,

and sensors (PPY, PEDOT, PANI, etc..)

• Metal oxides : mediators for electrocatalytic processes (MnO2 and RuO2) and

may feature electrochromic and semiconductive properties

(e.g.WO3 and TiO2)

This enables integration of the energy storage capability and of

the target function at materials level

12

Supercapacitors at LEME

1

• High Specific Energy Supercapacitors

- Electronically conducting polymers

- Mesoporous carbons

- Ionic Liquids

• Supercapacitor Integration

- Solar Capacitor

- Supercapacitive Microbial Fuel Cells

• Supercapacitor Miniaturization

- Melanine flexible SC

- Supersonic Cluster Beam Deposition

- TransCap: and integrated SC-Transistor

Supercapacitors of high specific energy

Emax= 1/2CSCVmax2 Pmax= Vmax

2 /4 ESR

increase maximum cell voltage Vmax

-advanced electrolytes of wide ESW

good conductivity, safety and wide

operative T range

increase supercapacitor specific capacitance Csc

- capacitive carbons (optimized porosity and surface chemistry)

- pseudocapacitive materials charged/discharged by fast redox processes

(noble metal oxides, conducting polymers, lithium intercalation materials)

IONIC LIQUIDS

University of

Bologna

33

2005-2009

M. Lazzari, F. Soavi, M. Mastragostino, J. Electrochem. Soc. 156 (2009) A661-A666.

galvanostatic cycles at 20 mA cm-2 60°C

High-voltage EDLC (ionic liquid electrolytes)

9.9 31 20 22 3.7 1.49 15-20

Pmax

kW kgc.m.-1

Emax

Wh kgc.m.-1

ESR

Wcm2

Csc

F gc.m.-1

Vmax

V w+/w-

wc.m.

mgc.m.cm-2

fade of capacitance <5% on 20,000 deep cycles with Vmax of 3.5/3.8V

cut-off voltage: Vmax = 3.7 V; Vmin = 55% Vmax

Electrodes prepared at pre-industrial scale: mesoporous commercial carbon treated at 1050°C in Ar

for 2 h (ACT), 100 F g-1; electrode composition: 5% pTFE and 95% C

wc.m.= total composite electrode loading

Cell prototype 3.7V - 340 F

Solar capacitor

Perovskyte solar cell – ionic liquid based

electrochemical double layer capacitor

900 950 1000 1050 1100 1150 12000.0

0.2

0.4

0.6

0.8

1.0

1.2

Light Dark Light

Volta

ge

(V

)

time (s)

pDSSC-EDLC

DSSC OCV

(scheme 2a)

b)

0 2 4 6 8 10-35

-30

-25

-20

-15

-10

-5

0

Ligth

Dark

time (s)

I (m

A)

f)

pDSSC-EDLC

DSSC @ 0V

+

Electrochemical Double Layer

Capacitor (EDLC)

---

-----

C

A

T

H

O

D

E

A

N

O

D

E

+

+

+

+

+ + + +

+ + + +

+

+

+

+

+

+

+

+- - - -

- - - -

---

--

-

-

+

+

+

+

-

+

--

-

+

+

+ +

-

-

- +

Canode

Ranode

RbulkCcathode

Rcathode

LOAD

C a

t

h

o

d e

Anode

O2

H2O

Reduction

Organic

compounds

CO2

H+

e-

Anodophillic

bacteria

Oxidation

Rext

OH-

Microbial Fuel Cell (MFC)

Microbial Fuel Cell Integrated with Self-Powered SC

Supercapacitive

Microbial Fuel Cell

(SC-MFC)

17

biotechnology for

simultaneous

wastewater

treatment and

energy production

but low power

output 0

2

4

6

8

10

12

14

16

18

20

0 5 10 15 20 25 30 35 40 45 50

Pm

ax (

mW

)

Current (mA)

AC-AdE BOx-AdE Fe-AAPyr-AdE

Sustainable materials

Melanin-based SC

15 P. Kumar et al, J. Mater,. Chem. C, 2016, DOI:10.1039/C6TC03739A

18

Figure 5. Melanin-based flexible micro-supercapacitors with ~200 µg/cm2 melanin loading on each

electrode. (a) Optical image of the micro-supercapacitor (total three micro-supercapacitors) on a

flexible PET substrate. (b) Specific capacitance and specific capacity vs. scan rate of CV taking into

account the total melanin loading of the two electrodes (32 µg). (c) Galvanostatic charge/discharge

cycles with three different values of the current density (0.625, 1.25, and 12.5 mA/cm2). (d) Ragone

plot extracted from the galvanostatic discharge cycles at different values of the current density

(0.625, 1.25, 6.25, 12.5 a nd 25 mA/cm2). The area of each electrode is 0.08 cm

2.

a

FlexibleMelanin mSC

Flexible melanin based micro-supercapacitors may serve in biocompatible and biodegradable

power sources for applications such as implantable medical devices and wearable electronics.

Eumelanin

Heterogeneous macromolecule

+ redox forms +

Natural pigment in animals, plants, human body (skin, eyes, inner ear, brain, hair)

melanin as active material in energy storage systems

Sustainable Miniaturization Processes

Supersonic Cluster Beam deposition (SCBD)

Supersonic Cluster Beam Deposition (SCBD) of nanostructured cabon (ns-C) electrodes

16

• thickness control (<< m)

•Low density (0.5 cm3/g)

• High porosity (700 m2/g)

• No binder, no carbon activation

• RT procedure for T sensitive substrates

L.G. Bettini et al, Electrochim. Acta, 170 (2015) 57

F. Soavi et al, J. Power Source, 326 (2016) 717

500 nm-thick

P-type Channel Electrolyte Gate Stacking

MEH-PPV N1113TFSI Activated Carbon sandwich

PEDOT:PSS polystyrenesulfonate (NaPSS) gel ns-C by SCBD planar, flexible

Z.Yi et al., J. Polymer Science, Part B: Polymer Physics.,

(2016) DOI: 10.1002/polb.24244

ns-C

SCBD

J. Sayago et al. J. Mater. Chem. C, 2014, 2,10273

J. Sayago et al., J. Mater. Chem. C, 2014, 2, 5690

J. Sayago et al., Appl. Phys., 117 (2015) 112809 21

TransCap: an integrated

electrolyte gated transistor (EGT) – hybrid SC

TransCap:

the proof-of-concept

potential steps at 0.8 V – 4s

J. Sayago, U. Shafique, F. Soavi, F. Cicoira, C. Santato, J. Mater. Chem. C, 2014, 2,10273

MEH-PPV/ionic liquid N1113TFSI/activated carbon

TransCap can operate with the channel

open (doped) without being connected

to an electric grid for relatively short times

To switch ON:

ETransCap= Igs dt = 53 J

ETransCap is then delivered upon switch OFF

with an efficiency of 99.5%,

.

22

8 10 12 14 16 18200

0

-200

-400

-600

Time (s)

I ds (

A

)

80

40

0

-40

-80

Po

we

r gs (

W

)

channel doping and

Sc charge at

|Vgs

|=0.8V

channel undoping and

Sc discharge at

|Vgs

|=0V

ON OFF

Channel current modulation

ON/OFF ratio 2 103 (Vgs +-0.8 V, Vds = -0.3V)

Acknowledgements

… and the funding:

Alma Mater Studiorum –Università di Bologna

RFO, Ricerca Fondamentale Orientata

Canada-Italy Innovation Award

ENEA and Italian Ministry of the Economic Development

Program Agreement “Electric System Research”

Special Thanks

To Carlo Santoro Plamen Atanassov

Alexey Serov

30 ….Thank you!!

Prof. P. Milani

Prof. P. Piseri

Special Thanks to

Luca Giacomo Bettini

Clara Santato

Fabio Cicoira

P. Kumar

Z. Yi

X.Meng

E. Di Mauro

F. Quenneville

J. Sayago

Prof. Catia Arbizzani

F. De Giorgio

I. Ruggeri

A. La Monaca

S. Intermite

Prof. Michael Grätzel

Prof. Anders Hagfeldt

Special Thanks to

Nick Vlachopoulos