Presented by MSc. Ir. Sheilla A. Odhiambo Email: sheilatieno@yahoo

1. TEXTILE BATTERIES FOR SMART TEXTILE SYSTEMS:Comparison of silver coated yarn electrodes, pure stainless filament yarn electrodes and copper coated yarn electrodes devices Presented by MSc. Ir. Sheilla A. Odhiambo Email: sheilatieno@yahoo.com PhD student, Gent University, Department of Textiles,& Moi University , Department of MIT THE IEK INTERNATIONAL ENGINEERING CONFERENCE AT KICC, MAY 9th -11th 2012, NAIROBI, KENYA

2. Contents • Brief introduction to Smart textile & System • Energy storage • Textile batteries • Literature report highlights on smart textile batteries/energy storage devices • Fabricated battery/energy storage devices • Devices fabrication and charging procedure • Results and discussions • Conclusion • Acknowledgement

3. Smart textiles

4. Smart textile system configuration

5. Energy storage • Electrochemically – Electrochemical cells (standard Battery ,1.5 Volts) Consist of Anode, cathode, electrolyte, separators, current collectors • Electrically – Electrostatic capacitors Consist of Conductive plates &dielectric material

6. Types of batteries • Primary Batteries : non- rechargeable • Used once and discarded • Example zinc carbon batteries and alkaline batteries • Have higher energy densities than rechargeable • Secondary batteries – Rechargeable • Applying electrical current reverse the chemical reactions that occur during use • Can be used for several cycles, until its performance decline due to wear Types : - Wet cell : Lead acid battery, - car battery. Gel batteries : Semisolid electrolyte to prevent spilage Dry cell :Lithium ion cells used in phones and laptops

7. Why textile batteries? • Flexible • Lightweight • Comfortable • Integrated into textile matrix • Safe • Maintenance?

8. Example of textile batteries from Literature (1) Rechargeable electronic textile battery by Bhattacharya et al 2009 PEDOT based charge storage device on a textile substrate The PEDOT coats are placed over three, silver coated polyamide yarns interwoven in the substrate’s weft

9. Example of textile batteries from Literature (2)Lithium ion textile batteries by Hu et al 2011 Porous textile structure: Pure PET dispersed with CNT

10. Example of textile batteries from Literature (3)Solid electrolyte based lithium battery by Liu et al 2012 Top row: photographs of a flexible battery made of binding individual cathode, anode and polymer electrolyte films Middle row: resulting battery is highly stretchable Bottom row: battery stripes (black) woven into a textile (blue and red cotton threads) using Dobby loom. The stripes are connectorized in series with conductive threads (metallic brown) Two textile electrodes are formed by the conductive threads at the textile extremities

11. Example of textile based supercapacitor (4) Flexible textile supercapacitors from nanofibres by Larforgue et al 2010 C) SEM Image of Active materials (PEDOT) nanofibres, D) sem image of the separator, (PAN nanofibres)

12. Contents • Brief introduction to Smart textile & System • Energy storage • Textile batteries • Literature report highlights on smart textile batteries/energy storage devices • Fabricated battery/energy storage device • Device fabrication and charging procedure • Results and discussions • Conclusion • Acknowledgement

13. Fabricated battery/energy storage device (methodology) • A laminate of textile substrate was made from cotton/polyester (5 cm by 5 cm), • 3 yarn electrodes are sewn on to the top most layer -pure stainless steel filament yarn electrodes, -copper coated yarn electrode, -silver coated yarn electrodes • The top surface is covered by TPU (Thermoplastic polyurethane, and a space 10 by 6mm left around the electrodes • PEDOT: PSS ((Poly (3,4ethylenedioxythiophene):polystyrenesulphonate)is applied here on the left space, layer by layer under the oven • The devices are charged and discharged, measured by voltage decay.

14. Fabricated battery/energy storage device made from silver coated yarn electrodes ,and pure stainless steel filament yarns electrodes, 2011-2012 by SO

15. Circuit for charging & discharging the samples

16. Results and Discussion (1) • -sharp decrease of the voltage V in the beginning of the discharging process, as soon as the switch S is opened. • -Steel filament yarns electrode devices could hold more charge compared to the others, and copper coated yarns could barely hold the charge.

17. Results and Discussions (2) • It is not surprising to learn that the charging time tch will be comparable when the discharging lasts for several hours for the active samples • Silver coated electrodes and pure stainless steel filament yarns electrodes samples can be cycled a number of times (up to10 times), comparable to the number of cycles for batteries reported by Liu et al, and Bhattacharya et al

18. Conclusion • Diffusion of silver ions into PEDOT as mentionedrecently in literature would not be the only responsible mechanism for the observed phenomena. • Stainless steel filament yarn performed better than the silver coated yarns electrodes and copper coated yarn electrodes. • The results motivate the making of a functional textile battery integrated within the textile structure

19. Acknowledgements • MU-VLIR UOS project for the financial support for her research and stay at the University of Gent. • Moi University management • Prof. ir. Lieva Van Langenhove, and Dr. Carla Hertleer from department of Textiles, Gent University. • Prof. De Mey from the department of electronics and information systems, Gent University. • Prof. Githaiga Department of MIT Moi University. • Prof. Dr.-ING. Harry L. Kaane, HigherrEducation Science and Technology secretary

20. Q &A Thank you