ORGANIC ELECTRODE MATERIALS AND THEIR APPLICATIONS IN RECHARGEABLE BATTERIES

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1 ORGANIC ELECTRODE MATERIALS AND THEIR APPLICATIONS IN RECHARGEABLE BATTERIES Assoc. Prof. Burak ESAT Fatih University, Department Of Chemistry Istanbul-Turkey COST-EXIL October 2015 in Belek Burak Esat 1, Sümeyye Bahçeci 1, Sevda Akay 1, Muhammed Aydın 2, Anton Momchilov 3 1 Fatih University Department of Chemistry, Istanbul/Turkey 2 Gebze Institute of Technology, Gebze Kocaeli/Turkey 3 2Bulgarian Academy of Sciences

2 Outline Introduction Early History-Conducting Polymers(CP) Redox Polymers (RP) Organo-sulphur Compounds Carbonyl Compounds Nitroxides Others Our Results Nitroxide Based RPs as Cathodes Anthraquinone (AQ) Based RPs AQ- Functionalized Reduced Graphene Oxide (RGO) Conclusions Acknowledgements

3 History of Organic Batteries Based on Organic Polymers as Electrodes Synthesis and use of organic conjugated polymers as electrode materials started after the pioneering work of McDiarmid, Heeger and Shirakawa in mid-1970s A. Moliton et al.,polym. Int. 53: (2004)

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5 Conjugated Polymers Cont d Disadvantages: - Low charge capacity of battery due to low doping levels attainable - Low battery stability & cycle-life Alan J. Heeger: Semiconducting and metallic polymers, Nobel Lecture 2000

6 Redox Polymers Redox Polymers are the polymers with non-conjugated backbones which have electro-active groups incorporated into their structures either as pendant groups or as a part of their backbone. Advantages: -Light-weight -Flexible -Moldable into different shapes &sizes -Low T manufacturing -High theoretical charge capacity -High rate capability possible -Good cycle performance possible -Environmentally benign

7 Redox Polymers Sulfur Based Materials

8 Carbonyl Based Materials

9 Organic Radical Based Materials- Organic Radical Batteries Organic Radical Polymers (ORP) are polymers bearing stable organic radicals as pendant groups. An Organic Radical Battery (ORB) can be defined as a battery that utilizes a polymeric material (pure or composite) with pendant redox active organic radical in at least one of its electrodes. Hiroyuki Nishide and Kenichi Oyaizu, Science 2008: Vol. 319 no pp DOI: /science

10 ORB Redox Activity of Organic Radicals R + e - e R - e + e R n-type doping p-type doping A Totally Organic Radical Battery Oyaizu K., Nishide H., Adv. Mater. 2009,21,2339

11 Nitroxide Type Radicals Suga T., Nishide H., Interface. Winter 2005, 32.

12 Theoretical Capacity (mah/g)= Polyacrylate P- Type Organic Radical Polymers Polystyrene (n) monomer (g/mol) 1000 Polyether Polynorbornene Polyisocyanate Nishide H. et al IUPAC, Pure and Applied Chemistry 81,

13 N- Type Organic Radical Polymers C C C Nishide H. et al IUPAC, Pure and Applied Chemistry 81,

14 Graphite Anode/ORP Cathode The power output per battery with a charge capacity of 5mAh increased to 7kW/L (1.4 times the level of conventional units Suga T., Nishide H., Interface. Winter 2005, 32.

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16 Some Organic Cathode -Active Redox Polymers Synthesized by Our Group

17 CR 2016 Coin Type Batteries Cathode Composite : 20-40% Polymer 50-70% Carbon 10% PVdF Binder

18 Theoretical Charge Capacity = 91 mah/g Specific Charge Capacity= 77 mah/g Specific Energy Capacity= 275 mwh/g Theoretical Charge Capacity = mah/g Specific Charge Capacity= 70 mah/g Specific Energy Capacity= 250 mwh/g Theoretical Charge Capacity = 91 mah/g Specific Charge Capacity= 36 mah/g Specific Energy Capacity= 175 mwh/g Theoretical Charge Capacity = mah/g Specific Charge Capacity= 80 mah/g Specific Energy Capacity= 280 mwh/g

19 Malonyl Tempo Diester Substituted Thiophene Theoretical Capacity= mah/g Theoretical Capacity = (n) monomer (g/mol) 1000 Aydin M., Esat B., Journal of Polymer Research, 2015 available on-line

20 Polymer & Composite Characterization Polymer SEM image Composite SEM image Current (A) Composite Poliymer Composite (Polymer/Graphite/PVDF:20/70/10) Voltage (V) -Polymer : E ox : 0.75V, E red : 0.66V, -Composite : E ox : 0.79V, E red : 0.65V.

21 V at 0.1 ma (~0.3C) Specific Energy Capacity (mwh/g) Voltage (V) Specific Charge Capacity Specific Energy Capacity= Cycle ID 180 mwh/g Charge Discharge Specific Charge Capacity (mah/g) Specific Charge Capacity= Cycle ID 55 mah/g Charge Discharge PROBLEM: Capacity fading due to polymer dissolution

22 105 3V 3.9V 0.2 C 5 mol% Thiophene added into polymerization rxn mixture to decrease solubility in electrolyte Specific Charge Capacity (mah/g) Charge Discharge Specific Charge Capacity= 80 mah/g Less soluble polymer= Smaller capacity fading Cycle ID Voltage (V) 3,8 3,7 3,6 3,5 3,4 3,3 3,2 3,1 0,2 C 0,5 C 1 C 2 C 4 C Specific Energy Capacity (mwh/g) Specific Energy Capacity= 280 mwh/g Charge Discharge 3,0 2, Capacity (mah/g) Cycle ID

23 Anode Materials: Quinones Synthesis

24 Anode Materials: Quinones Theoretical Charge Capacity = mah/g Scan Rate= V/s 8 Current (A) Voltage vs. Ag/Ag + (V) Vs Ag/AgCl

25 Organic Electrolyte

26 Aqueous Electrolyte

27 AQ Functionalized Reduced Graphene Oxide (RGO)

28 AQ Functionalized Reduced Graphene Oxide (RGO) Synthesis

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30 Conductivity RGO-AQ 50%: 657 S/m RGO-AQ-AQ 200%: 517 S/m RGO-AQ 500%: 316 S/m (RGO-AQ 50% = AQ to RGO Ratio =50% w/w during preparation)

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32 RGO-AQ 30% NaOH NiOOH

33 Conclusions We have proved that organic RPs (Redox Polymers) with pendant TEMPO radicals which are obtained via simple & efficient low T organic synthetic methods can be used as cathode-active materials. The cathode materials initially showed charge capacities close to their theoretical capacities, but the capacity degraded over time in most of the cases possibly due to polymer dissolution or electrode material degradation These problems may be solved by: Appropriate electrolyte choice Chemical crosslinking of polymer or covalent attachment of the polymer on carbon surface Anthraquinone-bearig RPs can be used as anode-active materials although they show sluggish redox behavior in organic elecrolytes. AQ group is shown to be a good candidate in anode materials in high-rate aqoueous batteries when used with conventional cathode materials such as NiOOH. RGO functionalization with electro-active groups such as AQ and Nitroxide radicals is a good strategy which avoids the use of redundant polymeric backbones and is thus promising for increasing the capacity.

34 Acknowledgements This research has been supported by Fatih University (BAP P _G) TUBITAK (Project # 112T516 & 114Z295)

35 Thank you for your attention