Developmet of flexible electrodes and lightweight capacitors

• Autores: Maricruz Saborío González
• Directores de la Tesis: Carlos Alemán Llansó (dir. tes.), Francisco Estrany Coda (codir. tes.)
• Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2018
• Idioma: español
• Tribunal Calificador de la Tesis: Elisabet Engel López (presid.), David Zanuy Gomara (secret.), Eric A. Perpète (voc.), David Curco Cantarell (voc.), Albert Poater i Teixidor (voc.)
• Programa de doctorado: Programa de Doctorado en Polímeros y Biopolímeros por la Universidad Politécnica de Catalunya
• Materias:
  • Física
    • Química física
      • Electroquímica
  • Ciencias tecnológicas
    • Tecnología energética
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• Resumen

  • This work has focused on the study and development of hierarchically, flexible electrodes and lightweight capacitor using as a source of flexibility. the y-polyglutamic acid (y-PGA) and as an electroactive polymer the poly(3,4-ethylenedioxythiophene) (PEDOT) in composite with alumina (Al2O3),Initially, the PEDOT/Al2O3 composite electroactive film was studied under different monomers: clay proportion and considering the amphoteric behavior of the Al2O3, the analysis of the pH affectation was done. Further, the multi-step in situ polymerization was studied. The experiments demonstrated that the 4:1 monomer: Al2O3 proportion, the multi-step basic medium (pH 8.8) (due to the proximity to the isoelectric point of the filler) favors the electrochemical properties with respect to pure PEDOT. The aforementioned variables combination displays an increment of 55% in specific capacitance (SC) (141 F g-1) compared to the pristine PEDOT. The values obtained demonstrate the synergetic effect of all the variables mentioned and the participation of the filler as a secondary doping agent facilitating the ion mobility.Secondly, the assembly and development of lightweight electrodes was achieved based on the supramolecular incorporation of PEDOT particles into an aqueous biohydrogel (y-PGA). Subsequently, a 20% w/w PEDOT particles were dispersed to give the electroactive characteristic to the gel, following by an extra step of in situ electropolymerization of poly(hydroxymethyl-3,4- ethylenedioxythiophene) (PHMeDOT) to join and increase the conductive polymer connections. Results revealed that electrochemical performance depends of the polymerization time, in this case, the optimum results obtained was the 7h polimerization electrode with a SC 45.4 ±0.7 mF cm-2 from cyclic voltammetry (CV) and charge-discharge (GCD) long-term stability. Finally, the applicability in lightweight and flexible energy-harvesting systems was verified by the LED bulb test. As a third step, a new solid organic symmetric capacitor was constructed, mingling the best results obtained from the previous studies as discussed. Two self-supported p-doped electrodes of y-PGA, PEDOT microparticles, PHMeDOT (2h electropolymerization) with filler of Al2O3 were produced. The electrodes were joined to a supporting solid ¿-PGA electrolyte doped with NaHCO3 salt from the synthesis step and functioning later as the electrolyte The electrochemical performance suggested an excellent prototype stability after 2000 charge-discharge cycles evidencing through an only 8% SC loss, evidencing an excellent stability.This thesis also focused in the n-doped PEDOT-polycation ionene electrode development. As a first step, a synthetic electrochemical protocol was followed to produce an n-doped PEDOT using macromolecular dopant agent, specifically, 1,4- diazabicyclo[2.2.2]octane-based ionene bearing N,N’-(meta-phenylene)dibenzamide linkages (mPi) was established. The protocol consisted of a three-step process , individually optimized: (1) preparation of p-doped (oxidized) PEDOT at a constant potential of +1.40 V in acetonitrile with LiClO4 as electrolyte; (2) dedoping of oxidized PEDOT using a fixed potential of –1.30 V in water; and (3) redoping of dedoped PEDOT applying a reduction potential of –1.10 V in water with mPI. The results obtained displayed a comparable doping level with respect tothe doping level obtained in case of TMA. Nevertheless, the PEDOT doped with mPi revealed better thermal stability and hydrophilicity than the former pristine p-doped and dedoped PEDOT. The final work, considers the influence of the ionene topology on the properties of n-doped PEDOT by comparing three isomeric topomers. The highest doping level was obtained for the para-isomeric ionene-containing electrode, even though the content of ortho- and meta-topomers into the corresponding ndoped PEDOT:ionene electrodes is greater , the topomers interactions as well were related with the hydrogelation of the ionenes.