Full text
| |
| Author(s): |
Raissa Venâncio
Total Authors: 1
|
| Document type: | Master's Dissertation |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Elétrica e de Computação |
| Defense date: | 2022-09-15 |
| Examining board members: |
Hudson Giovani Zanin;
Leonardo Morais da Silva;
Gustavo Doubek
|
| Advisor: | Hudson Giovani Zanin |
| Abstract | |
In recent years, there has been a technological race for efficient storage supplies to fulfill the exponential growth in energy demand with the insertion of sustainable solutions in the traditional matrix. Supercapacitors are a hot topic among these devices due to their high cyclability, rapid load capacity, and reliability. However, their electrochemical stability mostly depends on the ion/solvent and ion/pore interaction of its main components, and the incompatibility between such materials can accelerate the aging process and decrease device performance. In this context, we analyzed the compatibility of TEABF4-EC: DMC at multi-porous carbon electrodes, and with the best electrode material, we deciphered the degradation mechanisms occurring at the EDL interface through combined Raman and mass spectroscopy operando analysis. The first part of the study indicates AC as the best electrode material for high capacitance and energy density applications. In which the Raman operando highlighted the ion insertion inside very narrow pores, affecting the material's vibrational mode and causing the Fermi level shift. For mesoporous carbon, this phenomenon is much less pronounced. However, the graphite presented the BF4- insertion into its layers resulting in a capacitance three orders of magnitude higher than expected for ion adsorb onto graphite. In the second part of this study, we report different organic electrolytes' behavior on MWCNT and AC electrodes. The results showed the anomalous ion transport process that occurs within irregular pores. Furthermore, in-situ analyzes demonstrated the high stability of carbon-based electrodes that enter a state of decomposition at high voltages (above 2.5 V) combined with TEABF4-PC. It was noticed that the system consumes most of the oxygen produced, forming by-products of CO and CO2, while the hydrogen appears in reduced amounts due to the control of the organic solvent composition. In summary, the residual gas analysis provided important information about the composition of the electrodes and interfacial reactions of aging (AU) | |
| FAPESP's process: | 20/14968-0 - Electrodes and electrolytes characterization under dynamic conditions: analysis of evolved gases in different cell assemblies and abuse conditions |
| Grantee: | Raissa Venâncio |
| Support Opportunities: | Scholarships in Brazil - Master |