Broadening Integration of Printed Power Sources with Electronic Systems: Rechargeable

Printed Power Sources (Grant: SP/05/02/14)

Jagdeep Sagu, Nicola York, Darren Southee, Upul Wijayantha

d.j.southee@lboro.ac.uk

IeMRC Final Conference Feb 17th 2015 11.20am

Previously (Brunel) Offset Lithography Voltaic Cells……….

Primary cells – lit an LED

Lithographically Printed Voltaic Cells IeMRC FE/05/01/02 – 09/2005 to 08/2006

05/2007. “Lithographically Printed Voltaic Cells”. D. Southee, G. Hay, P. Evans, D. Harrison. UK Patent Application No. 0610237.0 - PCT Application (WilliamsPowell legal reference no.N18679).

We had joy, we had fun………………….

Integration of Printed Power Sources with Electronic Systems (Grant no. 774611MM-CONWAY 10/2006 to 05/2008 )

Powered a greeting card for a month….

Broadening Integration of Printed Power Sources with Electronic Systems: Rechargeable Printed Power Sources (Grant: SP/05/02/14 08/14 to 12/14)

The aim of the IeMRC funded “ Broadening” project:• Determine feasibility of making rechargeable energy storage devices using mass

produced printed electrodes• Make a demonstratorWhat we have done:• Characterise the original offset litho electrodes and the new flexo electrodes

(Gwent inks) • Construct a range of supercapacitors using various electrolytes

What is a supercapacitor?

based on constant current dischargeP. Sharma, T.S. Bhatti / Energy Conversion and Management 51 (2010) 2901–2912 2903

Electrochemical Double Layer (Super) Capacitor

What is a supercapacitor?

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4

Need high surface area electrode material

Energy storage is strongly effected by the electrolyte’s electrochemical stability window~ 1 V for aqueous (high conductivity)~2-3 V for organic (medium conductivity)~3-6 V for Ionic Liquid (low conductivity)

Resistance needs to be low as possible to achieve high power

Capacitance can be determined by cyclic voltammetry or charge discharge measurements

Offset Litho Electrodes in 6 M KOH – filter paper separator

supercapacitor testing

Device Per cm2

Capacitance 0.0137 F 0.000453 F/cm2

Series Resistance 2.74 Ω ‐Energy 0.00438 J 0.000145 J/cm2

Power 0.0584 W 0.00193 W/cm2

New Electrode Testing in 6 M KOH, filter paper separator

0 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800-1-0.750x10

-1-0.500x10

-1-0.250x10

0

-10.250x10

-10.500x10

-10.750x10

E / V

i / A

0 50.0 100.0 150.0 200.0 250.0 300.0-0.100

0.150

0.400

0.650

0.900

t / s

E / V

Device Per cm2

Capacitance 0.0500 F 0.00165 F/cm2

Series Resistance 1.4 Ω ‐Energy 0.016 J 0.000529 J/cm2

Power 0.114 W 0.00377 W/cm2

Some issues……..

Sealed using laminator

• Sealing issues• Electrode wetting

0 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800-2-0.050x10

-2-0.025x10

0

-20.025x10

-20.050x10

-20.075x10

-20.100x10

-20.125x10

E / V

i / A

This prompted investigation of solid-state supercapacitors

Solid state PVA‐KOH supercapacitor

0 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800-1-0.400x10

-1-0.300x10

-1-0.200x10

-1-0.100x10

0

-10.100x10

-10.200x10

-10.300x10

-10.400x10

-10.500x10

E / V

i / A

• PVA gluey gel• Each electrode is coated in the gel, and allowed to dry• Then the two electrodes are glued together using the same gel and allowed to dry

briefly before sealing• No separator is required

Reproducibility of 4 electrodes from batch 1At 500 mV/s

Comparison of the solid state supercapacitors:Litho vs. Flexo

Demonstrator 1

0 0.250 0.500 0.750 1.000 1.250 1.500 1.750 2.000 2.250 2.500-1-0.400x10

-1-0.300x10

-1-0.200x10

-1-0.100x10

0

-10.100x10

-10.200x10

-10.300x10

-10.400x10

-10.500x10

-10.600x10

E / V

i / A

The stack of supercapacitors (charged to 2.4 V) were able to power a 1.6 V yellow LED for around 90 seconds.

Flex ‐ testing

0 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800-1-0.500x10

-1-0.250x10

0

-10.250x10

-10.500x10

E / V

i / A

Blue: before rollingRed: after rolling

Demonstrator 2

• The printed electrodes were modified by adding an activated carbon layer• This time an ionic liquid was used as the electrolyte, bis-trimethylamonium bi tri

fluoromethyl sulfonimide to give a larger voltage. • The two electrodes were separated using filter paper.• Two of these supercapacitors were connected in series. • With this combination, the supercapacitors can be charged to 6 V, and give a

capacitance of around 0.5 F.

-1.000 0 1.000 2.000 3.000 4.000 5.000 6.000 7.0000-0.075x10

0-0.050x10

0-0.025x10

0

00.025x10

00.050x10

00.075x10

00.100x10

E / V

i / A

Light for over 1 min, gradual fadingcyclic voltammetry at 100 mV/s

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Conclusions and future work

Conclusions• Useful rechargeable power sources can be made from printed electrodes.• The adoption of liquid electrolytes provides difficult challenges.• Solid-state supercapacitors incorporating printed electrodes have been fabricated,

and characterised.• The aim to encourage and entice industry and academic partners into a larger

collaborative project is now on offer?

Future Work• Use higher surface area electrode materials with high conductivity• Improve electrolytes

The Future?

Source: Cisco website