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2017 ACS Spring National Meeting Presentation Slides

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Manipulate the Chemical Composition and Substrate Nature to Push the Cycling Stability Limit of Polypyrrole (oral presentation, ENFL #114, 253rd ACS National Meeting, San Francisco, CA, 2017)

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2017 ACS Spring National Meeting Presentation Slides

  1. 1. Manipulate the Chemical Composition and Substrate Nature to Push the Cycling Stability Limit of Polypyrrole Tianyu LIU Yat Li Lab Department of Chemistry and Biochemistry University of California, Santa Cruz 04/2017
  2. 2. UC Santa Cruz
  3. 3. The Li Lab Chem. Soc. Rev., 2012, 41, 5654-5671 ACS Nano, 2013, 7, 8728–8735 Adv. Mater. 2014, 26, (17), 2676 Photo-electrochemical Water Splitting Supercapacitor Microbial Fuel Cell Sustainable Energy
  4. 4. Outline  Supercapacitors  Cycling Instability of Polypyrrole  Strategies to Improve Cycling Stability  Experimental Results  Summary
  5. 5. Background (Supercapacitors)
  6. 6. Structure of Supercapacitors Charge storage devices Large surface area 5 μm ZnO Nanowires 10 μm Graphene Aerogel
  7. 7. Capacitance Charge storage ability Charge storage mechanisms Electrical Double Layer Capacitance Pseudo- capacitance Activated Carbon, CNT, Graphene etc. Conjugated polymers, metal oxides etc. 𝑪𝒂𝒑𝒂𝒄𝒊𝒕𝒂𝒏𝒄𝒆 = 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦 𝑃𝑜𝑡𝑒𝑛𝑡𝑖𝑎𝑙 𝑊𝑖𝑛𝑑𝑜𝑤
  8. 8. Conjugated Polymers Polyaniline (PANI) Polypyrrole (PPy) Advantages: Ease of fabrication (electrodeposition, chemical polymerization) Excellent electrical conductivity (100~10000 S/m) High theoretical capacitance (500~3400 F/g) – Pseudocapacitive Material Environmentally benign
  9. 9. Charge Storage Mechanism PPy: Phys. Chem. Chem. Phys., 16, 3523-3528 (2014) A- A- + + A- + · +n A- -n e-+n e- -n A- De-doping +n A- -n e-+n e- -n A- Doping De-doping Doping
  10. 10. Counter-ions PPy: Phys. Chem. Chem. Phys., 16, 3523-3528 (2014) A- A- A- + + + · +n A- -n e-+n e- -n A- De-doping +n A- -n e-+n e- -n A- Doping De-doping Doping A- A- A-
  11. 11. Drawbacks of Conjugated Polymers Poor cycling stability Structural pulverization - Loss of active material Nano Lett., 14, 2522–2527 (2014)
  12. 12. Volumetric Deformation Phys. Chem. Chem. Phys., 16, 3523-3528 (2014) A- A- A- + + + · +n A- -n e-+n e- -n A- De-doping +n A- -n e-+n e- -n A- Doping De-doping Doping Swell SwellShrink Shrink
  13. 13. Drawbacks of Conjugated Polymers Poor cycling stability Structural pulverization - Loss of active material Nano Lett., 14, 2522–2527 (2014)
  14. 14. Drawbacks of Conjugated Polymers Poor cycling stability Counter-ion drain A- A- A- + + + · +n A- -n e-+n e- -n A- De-doping +n A- -n e-+n e- -n A- Doping De-doping Doping Collapse of ion channels Less electrically conductive
  15. 15. Motivation Instable Polypyrrole Electrodes
  16. 16. Motivation Instable Polypyrrole Electrodes Stable How?
  17. 17. Soft Substrates Functionalized exfoliated graphite (FEG) Nanoscale, 7, 3581-3587 (2015) Structural Pulverization?
  18. 18. Immobilized Counter-ions β-naphthalene sulfonate anion (NS) sulfate anion (S) Counter-ion Drain?
  19. 19. Results & Discussions Adv. Funct. Mater., 25, 4626-4632 (2015)
  20. 20. Names FEG/PPy-NS: PPy film deposited on the FEG and doped with NS anions FEG/PPy-S: PPy film deposited on the FEG and doped with S anions PPy-S: PPy film deposited on a piece of untreated graphite foil
  21. 21. Stability Performance Cycling stability CyclicVoltammogram 97% 83% 47%
  22. 22. Pulverization?
  23. 23. Counter-ion Drain? Energy dispersive X-ray spectra Electrolyte: 3 M KCl aqueous electrolyte S signal should be contributed only from the counter-ions doped in PPy
  24. 24. Device Assembly H2O → Electrolyte ← Separator + KCl Electrodes
  25. 25. Device Performance Cycling stability performance Ragone plot 97% Capacitance Retention (after 10,000 cycles)
  26. 26. Summary
  27. 27. Summary Polypyrrole Structural Pulverization Counter-ion Drain FEG Substrate Immobilized Dopant Excellent Durability
  28. 28. Acknowledgements Yu Song Prof. Yat Li Group, UCSC

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