Evaluación de las estrategias de mejora de estabilidad química y estudio de las propiedades electroquímicas de perovskitas de conductividad protónica para dispositivos electroquímicos de alta temperatura
[EN] The main objective of the research performed during this thesis involves the synthesis processing, and characterisation of ceramic materials for application as electrolytes in protonic ceramic fuel cells (PCFC) and protonic ceramic electrolyser cells (PCEC). The studied materials are the most r...
| Autor: | |
|---|---|
| Tipo de documento: | tese |
| Estado: | Versão publicada |
| Data de publicação: | 2022 |
| País: | España |
| Recursos: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositório: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/275093 |
| Acesso em linha: | http://hdl.handle.net/10261/275093 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Proton-conducting ceramics electrolytes Yttrium-doped barium cerates (BCY) Yttrium-doped barium zirconates (BZY) Yttrium-doped strontium zirconates (SZY) Sol-gel synthesis Thin films Dip-coating Chemical stability Proton conductivity Halogen doping A-position deficiency Impedance spectroscopy Partial conductivity Transport numbers Sintering additives Electrolitos cerámicos conductores protónicos Ceratos de bario dopados con itrio (BCY) Circonatos de bario dopados con itrio (BZY) Circonatos de estroncio dopados con itrio (SZY) Síntesis sol-gel Láminas delgadas Inmersión-extracción Estabilidad química Conductividad protónica Dopaje con halógenos Deficiencia en la posición A Espectroscopía de impedancia Conductividad parcial Números de transporte Aditivos de sinterización |
| Resumo: | [EN] The main objective of the research performed during this thesis involves the synthesis processing, and characterisation of ceramic materials for application as electrolytes in protonic ceramic fuel cells (PCFC) and protonic ceramic electrolyser cells (PCEC). The studied materials are the most relevant proton-conducting ceramics electrolytes for commercial, high-temperature applications, namely barium and strontium cerates and zirconates with the ABO3 perovskite structure. The perovskites are doped in the B-position with trivalent cations, typically yttrium, to create oxygen vacancies, forming mobile protonic defects in humid atmospheres in the intermediate temperature range (500-800 °C). In general, these materials are characterised by poor chemical stability when submitted to CO2-containing atmospheres and high water-vapour partial pressures, particularly the barium-cerate family. Their use in PCFCs fed with hydrocarbons may be limited during operation since CO and CO2 are formed as by-products and are prone to react with the electrolyte. Hence, one aim of this doctoral thesis is the improvement in the chemical stability of proton-conducting perovskites in CO2-containing and high pH2O atmospheres to develop more versatile proton conductors. Improvements in the stability of PCFCs would lead to greater fuel flexibility, including the use of methane or bioethanol, in addition to enhanced adaptability to other technologies such as membrane reactors. Moreover, stable proton-conducting ceramics may be used in reversible electrochemical cells which can perform in either fuel cell or electrolyser mode in the same device, creating electrical energy from hydrogen conversion and producing hydrogen from electrical energy, as required. In this thesis, the impact of different processing strategies on the chemical stability, including the incorporation of halogens in the oxide-ion sublattice and the introduction of Ba deficiency, is studied, as well as the effects of these approaches on structural, microstructural and electrochemical properties. |
|---|