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| Author(s): |
Lucas Ponez da Mota
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Instituto de Química de São Carlos (IQSC/BT) |
| Defense date: | 2016-04-27 |
| Examining board members: |
Agnieszka Joanna Pawlicka Maule;
Carla Cristina Schmitt Cavalheiro;
Jose Pedro Donoso Gonzalez;
Ernesto Chaves Pereira de Souza
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| Advisor: | Agnieszka Joanna Pawlicka Maule |
| Abstract | |
The aim of the present study was to prepare and characterize polymer electrolytes (EP) based on poly(vinyl butyrate) (PVB) with different lithium salts (LiClO4, LiCF3SO3 and LiI/I2) and/or containing g-butyrolactone (GBL), and to apply them in electrochromic devices and solar cells. It was observed through electrochemical impedance spectroscopy that the PVB is able to solvate up to 40% in weight of lithium salt. It was found that the ionic conductivity of these samples, as a function of temperature, can be explained by Vogel-Tammann-Fulcher model, and the electrolyte PF04 (PVB with 40% of LiCF3SO3) had the highest conductivity value of 1,5´10-4 S/cm when compared to other samples. Infrared spectra of the samples showed a shift in the peaks corresponding to the carbonyl groups of the polymer matrix in response to their coordination with Li+ ions. The results of Raman spectroscopy confirmed the presence of the redox couple (I3-/I-) in the electrolyte with LiI/I2 (PVB04). The X-ray diffractograms of the PVB showed a broad peak centered at 20 (2q) com intensity of 800 cps. The addition of LiI/I2 and LiCF3SO3 to the polymer matrix decreased the intensities to 750 and 700 cps respectively, but not after the LiClO4 addition, which was explained by its not complete solvatation by the polymer matrix. The Scanning Electron Microscopy (SEM) pictures of electrolyte with 23% of LiClO4 (P04 sample) showed evidences of ion clusters on the surface. The analyzes via Differential Scanning Calorimetry (DSC) showed that an increase in the concentration of the salt added to the polymer matrix caused a decrease in glass transition temperature (Tg), and that electrolytes are about 44% crystalline. The electrolytes P04 and PF04 were applied to electrochromic windows (ECDs) and showed a transmittance difference of 10.5 and 9.3%, respectively between the colored and discolored states. The electrolyte with LiI/I2 was applied to dye sensitized solar cell (DSSC) generating a maximum photocurrent of 1.09 mA/cm2 and 0.41% of efficiency under irradiation of 100 mW/cm2. Gel electrolytes containing 90% of γ-butyrolactone were applied to DSSC and showed 5.82 mA/cm2 of photocurrent and 2.1% of efficiency. (AU) | |
| FAPESP's process: | 09/17564-9 - Poly(vinyl butyral)-based polymer electrolytes for electrochromic devices and solar cells |
| Grantee: | Lucas Ponez da Mota |
| Support Opportunities: | Scholarships in Brazil - Doctorate |