New generation ion conducting polymer electrolytes for electrochemical energy technologies

1. PhDof Industrial Engineering ResearchActivity on Energy New generation ion conducting polymer electrolytes for electrochemical energy technologies Maria Luisa Di Vona R. Narducci, L. Pasquini 17th October 2014

2. PEM anode cathode H2O + O2 H2 (+ H2O) cathodic process: 2H+ +2e- → H2 H+ anodic process: H2O → 1/2O2 + 2e- + 2H+ H2O ( H2O ) H+ electrocatalyst layers Systems based on Polymer Electrolyte Membranes (PEM) AEM-FC PEM-FC Redox flow batteries Electrolysers PhD of Industrial Engineering Research Activity on Energy

3. Polymer electrolyte membranes (PEM) fluorine Cationic Exchange Membranes Nafion Anion Exchange Membranes PhD of Industrial Engineering Research Activity on Energy Methylen ammonium Aromatic Polymers

4. Amphoteric Exchange Membranes PhD of Industrial Engineering Research Activity on Energy

5. A fuel cell consists of two bipolar graphite plates that hold a Membrane Electrode Assembly (MEA). Each MEA is a set of two electrodes sandwiched around a Polymer Electrolyte Membrane (PEM) .

6. Ideal Membranes Long life High conductivity Mechanical strength Controlled water absorption Chemical and thermal stability Low cost Low permeability to reactants E. Sgreccia M. Khadhraoui, M.L. Di VonaJournal of Power Sources 178 (2008) 667–670

7. Relations between membrane stiffness, hydration, morphology and conductivity Reproduced from Introduction To Polymers R.J. Young and PA. Lovell. CRC Press 1991 PhD of Industrial Engineering Research Activity on Energy

8. Possible solutions for improving membrane performances • …. Inorganic proton conductors Zirconium phosphates, heteropolyacids.. Composite Oxides SiO2, TiO2, ZrO2…. Polymer blends Thermal treatments Functionalization Cross-linking Modification of the polymeric backbone Block copolymers PhD of Industrial Engineering Research Activity on Energy

9. H3O+ (OH-) Strategies for improving Polymer Electrolyte Membranes Modified Polymers Composite Materials Hybrid Organic-Inorganic Polymers (SOSiPEEK) Inorganic-Organic Nanocomposites (F-TiO2) Fuel Cell Membrane Patent DE 10 2009 006 493A1 Thermal Treatments Blends (Cross-Linking) Hybrid Polymer Blends (SPEEK + SiPPSU) FCH-JULoLiPEM Project www.lolipem.eu

10. Covalent bonds Ionic bonds Chemical cross-link Van der Waals interactions Strategies for improving Polymer Electrolyte Membranes Knauth P, Di Vona ML. Solid State Ionics, 2012, 225, 255-259 PhD of Industrial Engineering Research Activity on Energy

11. DMSO, D Proton Exchange Membranes 2 H2 + O2 = 2 H2O High efficiency (up to 60%?) « Zero emission »! 80- 100 °C; RH 70-100% Cross-linking of SPEEK by thermal treatments PhD of Industrial Engineering Research Activity on Energy

12. XL- induced properties: low solubility in solvents low fuel permeability high dimensional stability enhancement of tensile strength reduction of ductility decrease of free volume enhancement of glass transition temperature Cross-linked (XL) aromatic polymers H. Hou, M. L. Di Vona, P. KnauthDurability of Sulfonated Aromatic Polymers for Proton- Exchange-Membrane Fuel Cells ChemSusChem 2011, 4, 1526 H. Hou, M. L. Di Vona, P. KnauthBuilding bridges: Crosslinking of sulfonated aromatic polymers-A review. Journal of Membrane Science 2012, 423, 113

13. Cross-linking of SPEEK by thermal treatments SPEEK solvent annealing soluble soluble soluble soluble soluble soluble Cross-link No cross-link Di Vona ML, Pasquini L, Narducci R, Pelzer K, Donnadio A, Casciola M, Knauth P. Journal of Power Sources, 2013, 243, 488-493; Di Vona ML, Sgreccia E, Muthusamy T, Khadhraoui M, Chassigneux C, Knauth P. Journal of Membrane Science, 2010, 354, 134-141

14. How does the cross-link (XL) reaction occur ? Covalent cross-linking during heat treatments of SPEEK membranes at T ≥ 140 °C occurs in presence of small quantities of DMSO. Electrophilic aromatic substitution by sulphonium ions (-SO2+) in activated positions occurs preferentially.

15. Mechanical properties: traction experiment Stiffness explores essentially weak bonds (low displacements): Van der Waals bonds; Defects, such as entanglements; Presence of water (distance between chains) Influence of Water: H2O and DMSO: high dielectric constant solvents Reduce ionic bond strength Reduction of stiffness and strength

16. Dynamic Mechanical Analysis No cross-link Cross-link E. Sgreccia, J.-F. Chailan, M. Khadhraoui, M. L. Di Vona, P. Knauth Journal of Power Sources 195 (2010) 7770–7775 Solid State Proton Conductors Eds. P. Knauth and ML Di Vona, 2012 Wiley Di Vona ML, Alberti G, Sgreccia E, Casciola M, Knauth P. International J Hydrogen Energy, 2012, 37, 8672-8680

17. Optimisation of proton conductivity: calculated and experimental data for SPEEK • Conductivity maximum at l ~ 90 • At 100 °C, s > 0.1 S/cm for l = 25 • This plot allows determining: • the maximum achievable conductivity • the conductivity for a certain hydration 100 °C “Memory Effect” 25 °C • Hydration of XL-SAP at high a(H2O) and high T! Only XL membranes can do this! 17 Knauth P, Pasquini L, Maranesi B, Pelzer K, Polini R, Di Vona MLFuel Cells,13, 79 (2013)

18. LoLiPEM Project Polarization results for MEAs based on cross-linked SPEEK membranes (EX-330) and a Nafion212 membrane (triangles). Excellent fuel cell characteristics for XL-SPEEK G. Barbieri, M. L. Di Vona, P. Knauth, R. Hempelmann, L. D. Beretta, B. Bauer, M. Schuster, L. F. Vega Journal of Power Sources, submitted

19. H2 + 2OH- 2H2O + 2e ½ O2 + H2O + 2e 2OH- H2 +1/2O2 H2O Ea = -0.84 V Ec = 0.39 V (pH = 14) AEM-FC 60°C, RH 100% Anion Exchange Membranes Use of non-noble metals Low stability  Low ionic conductivity 

20. Stability of cationic groups Hofmann elimination E2: antiperiplanar mechanism Is it possible to prevent E2 reactions? YES

21. Stability of cationic groups SN2 reaction Maybe Is it possible to prevent SN2 reactions? or………..

22. Stability of cationic groups 1,5-Diazabicyclo[4.3.0]non-5-ene (DBN) positive charge delocalized by resonance in the p system positive charge delocalized by long range interaction 1,4-diazabicyclo[2.2.2]octane (DABCO)

23. Stability of backbones AM-PSU Two strategies: Polymer cross-linking Delocalization of the positive charge Is it possible to prevent degradation reactions? Maybe Di Vona, M. L. Narducci, R. Pasquini, L. Pelzer, K Knauth, P. INTERNATIONAL J HYDROGEN ENERGY 39, 14039-14049, 2014

24. Mechanical properties of PSU-TMA membrane Typical tensile stress-strain curves of rigid TMA–PSU derivatives in hydroxide form (black: DAM = 0.39, red: DAM = 0.93) obtained at 25°C and ambient humidity E: elastic modulus σMAX: tensile strength ε@ break : elongation at break

25. conductivity in H2O Manning condensation?

26. Redox flow batteries Stationary electricity storage (“Smart grid”) Redox flow battery is a  rechargeable battery where rechargeability is provided by two chemical components dissolved in liquids contained within the system and separated by a membrane

27. Anion-Conducting Sulfamminated Aromatic Polymers by Acid Functionalization Anion Exchange Membranes SA-PEEK Cl- Br- NO3- HSO4- H2PO4- CH3CO2- L. Pasquini, P. Knauth, K. Pelzer, M. L. Di Vona, Solid State Ionics, Submitted

28. Water uptake at 25 °C Conductivity properties in water at 25 °C. The conductivity is stable after 1 week

29. The anion conductivity occurs in a range of low pH values Applications are interesting in all vanadium redox flow battery (high concentration of sulfuric acid; the hydrogen sulfate anion is the major charge carrier) . A higher ionic conductivity is expected due to the contribution of both hydrogen sulfate anions and protons B Schwenzer et al. ChemSusChem 2011, 4, 1388

30. Mechanical properties high tensile strength (1460 MPa) high elastic modulus (53 MPa) low elongation at break (6 %) High rigidity polymers potentially useful for separation membranes Permeability The vanadium permeability measured with dimethyl- and diethylamine sulfamminated polymers is 1.3x10-9 and 5x10-10 cm2/min, respectively. These values are 3 orders of magnitude lower than those of Nafion measured under similar conditions (1.4x10-6 cm2/min).

31. Micro-scale energy storage and conversion

32. Acknowledgments Riccardo Polini Luciana Luchetti Emanuela Sgreccia Tamilvanan Muthusamy Riccardo Narducci Luca Pasquini @ @ Giulio Alberti Mario Casciola Anna Donnadio @ Dr. Jedeok Kim NIMS (Japan) Prof. E. Smotkin Northeastern University, Usa Italian Ministry for University and Research Franco-Italian University (Vinci project) Thesis E. Sgreccia Cap III: R. Narducci, L. Pasquini

33. USaar (R. Hempelmann) Fumatech (M. Schuster) CUT (B. Grochola) Edison (D. Beretta) UMarseille (P. Knauth) URoma2 (ML Di Vona) MatGas (L. Vega) ITM-CNR (G. Barbieri) Acknowledgments Financial support: EUFuel Cells and Hydrogen Joint Undertaking www.lolipem.eu

35. Class I Class II No covalent or iono-covalent bonds Covalent or iono-covalent or Lewis acid-base bonds Hybrid systems:Synergic effect between Organic and Inorganic phases not achievable by physical mixing

36. Strategies to Form Hybrid Membranes Class II hybrids: Silylate-polymers

37. s e max [%] max [MPa] Mechanical properties: Tensile stress Strain Blends: E [MPa] Sulfonation reduces membrane strength! S-PPSU 7% Softmaterials SiS-PPSU 7% Silicon enhances membrane strength! Si-PPSU 7% E. Sgreccia et al., Journal of Power Sources, 178, 667 (2008)

38. Mechanism for Strengthening of Si-PPSU? Si-PPSU: calculated conformation Phenyl-silanol group limited chain mobility leads to a strong increase of Tg with respect to pure SPEEK

39. 0,1 0,0817x y = 2E-05e 0,01 0,0912x SPEEK y = 8E-06e s (Scm-1) SPEEK/ Si-PPSU 0,001 0,0001 0 20 40 60 80 100 RH/% Conductivity properties T = 100°C Conductivity is measurable and continues to increase at high RH Improvement in comparison to unmodified SPEEK, which swells!