Y. Maletin, N. Stryzhakova, S. Zelinskiy, S. Chernukhin, D. Tretyakov, S. Tychina How Electrochemical Science Can Improve the EDLC Performance AABC Europe 2013, Strasbourg, June 24-28

Presentation outline 1.Yunasko key targets 2.CV and galvanostatic measurements 3.Impedance measurements (EIS) 4.In-pore diffusion measurements 5.Recent test results: unit cells and modules 6.Company development 2 How Electrochemical Science Can Improve the EDLC Performance

3 How Electrochemical Science Can Improve the EDLC Performance Why SCs sometimes look like the Cinderella of energy storage market? 1.Billions were invested in Li-ion batteries over the last few decades resulting in a huge advance of this technology. 2.SC technology was developing rather slowly and was deemed to be rather complicated and expensive for many applications. Hence, Yunasko approach: 1.SCs must demonstrate by far the best performance in areas where they can compete with batteries or complement them. 2.Low cost and commercially available components should preferably be used.

Cell design for 3-electrode measurements 4 How Electrochemical Science Can Improve the EDLC Performance

CV: scanning the electrode potential to (+) 5 How Electrochemical Science Can Improve the EDLC Performance 0V corresponds to the equilibrium potential scan rate: 10 mV/s NOTE: potential range with Faraday processes cannot be used for long

6 CV curves: A - 3-electrode cell B - SC prototype How Electrochemical Science Can Improve the EDLC Performance A B

How Electrochemical Science Can Improve the EDLC Performance Charge accumulated in (-) or (+) potential range 7

Hybrid cell: CC charge-discharge curves 8 How Electrochemical Science Can Improve the EDLC Performance

DC=2.7V AC= 5mV Freq --> 0.1Hz to 10 kHz 1- poor 2- typical 3- optimized SC design: Impedance spectroscopy ( Nyquist plots ) How Electrochemical Science Can Improve the EDLC Performance 1 9

10 How Electrochemical Science Can Improve the EDLC Performance Impedance spectroscopy (capacitance and resistance vs. frequency)

Al-C 0.01 (in Yunasko technology) C ~ 0.05 Thus: El ~ 0.75 pore resistance ~ 0.6 SC resistivity (in.cm 2 ) total ~ 0.8 Though: El-in-bulk ~ 0.15 (electrode+separator thickness) Yunasko approach to reduce R and RC 11 How Electrochemical Science Can Improve the EDLC Performance

TEM image of carbon powder 12 Slit-shaped pores or just shear cracks of graphene layers How Electrochemical Science Can Improve the EDLC Performance

Why the in-pore electrolyte mobility is slow? 13 Pore width is mostly within 1 ÷ 3 nm ( is comparable with the Debye length ). There is no potential gradient in narrow pores, and therefore, diffusion is the only driving force for ions to move. ( Y.Maletin et al., 7 th EDLC Seminar, FL, Dec.1997 ) Diffusion can be slow due to strong interaction between the charged electrolyte species and conductive pore walls. How Electrochemical Science Can Improve the EDLC Performance

14 Correlation of in-pore diffusion coefficients with EDLC resistance Diffusion coefficients of Fc + cations in various NP carbons ( Rotating Disc Electrode measurements, see: A.J.Bard, L.R.Faulkner; Electrochemical Methods. Fundamentals and Applications (2 nd ed.); Wiley, 2001, p.335 ) NOTE: in bulk solution D eff = 10.1× m 2 /s How Electrochemical Science Can Improve the EDLC Performance

Test results 15 a) Also tested in ITS, UC Davis, CA; b) Also tested in JME, Cleveland, OH; c) Also tested in Wayne State University, Detroit, MI; d) Equipped with a proprietary voltage balancing system (patent pending). How Electrochemical Science Can Improve the EDLC Performance

16 Recent Yunasko EDLC modules How Electrochemical Science Can Improve the EDLC Performance 15 V, 200 F: max working voltage 16.2 V max surge voltage 18.0 V dc pulse resistance 0.5 mΩ mass 2.5 kg equipped with a proprietary voltage balancing system and temperature sensor

17 Yunasko competitive advantage: low heat generation Continuous cycling the module over 8 hours basic city duty cycle ΔT: cells in the centre cells at the edge How Electrochemical Science Can Improve the EDLC Performance Time, s V A, charge A, discharge

Ragone plot: EDLC vs hybrid devices 18 How Electrochemical Science Can Improve the EDLC Performance As tested in ITS, UC Davis, CA

Hybrid cell: cycle life (charge/discharge between 2.7 and 1.35 V) 19 How Electrochemical Science Can Improve the EDLC Performance

Hybrid cell: temperature/rate performance 20 How Electrochemical Science Can Improve the EDLC Performance

Company background and prospects 21 Principal researchers participate in various supercapacitor projects since 1989 YUNASKO Ltd: registered in the UK since 2010 Subsidiaries: YUNASKO-Ukraine: R&D, design bureau and pilot plant since 2010 YUNASKO-Latvia: industrial scale production will start in 2014 How Electrochemical Science Can Improve the EDLC Performance

R&D team: breakthrough story 22 How Electrochemical Science Can Improve the EDLC Performance

Conclusions 1.Electrochemical methods are a powerful instrument to show a way to SC improvements. 2.Yunasko technology* enables to significantly reduce SC resistance and to achieve the power density up to 100 kW/kg. 3.Yunasko hybrid devices* demonstrate by far larger energy and power density than competing hybrids. 4.First industrial scale production will soon be launched. 5.Yunasko is open to cooperation with investors and industrial partners. * US and EU patents pending 23 How Electrochemical Science Can Improve the EDLC Performance

Acknowledgements Many thanks to Dr. Andrew Burke (ITS) and Prof. John R. Miller (JME) for stimulating discussions and valuable help in testing Special thanks to Dekarta Capital Fund for investing in the Yunasko project Participation in EU FP7 Energy Caps project is very much acknowledged 24 How Electrochemical Science Can Improve the EDLC Performance

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