Cerâmicas ferroelétricas à base de BNT-BT para armazenamento de energia
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Data
2021-02-22
Autores
Rocha, Yasmim da Silva [UNIFESP]
Orientadores
Lente, Manuel Henrique [UNIFESP]
Tipo
Trabalho de conclusão de curso de graduação
Título da Revista
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Resumo
A migração da matriz energética mundial para consumo de fontes renováveis é uma tendência
atual. Esse fato vem impulsionado o desenvolvimento de dispositivos que armazenem energia,
dentre eles os capacitores. Esse mercado é dominado por cerâmicas à base de chumbo, um
elemento altamente tóxico para a saúde humana e ambiental. Com isso, diversas pesquisas têm
sido feitas com o objetivo de desenvolver capacitores livres de chumbo que sejam equiparáveis
aos produzidos com tal elemento. Os dielétricos à base de titanato de bário e bismuto estão entre
os mais pesquisados. Além de não serem tóxicos, tais dielétricos são menos densos do que os à
base de chumbo, o que colabora para a diminuição do peso nesses dispositivos. Realizando um
cálculo J/kg, os capacitores à base de BNT-BT que apresentarem densidade de energia
recuperável superior à 3.77 J/cm³ tornam-se mais efetivos do que os à base de chumbo. Sob essa
perspectiva, foi realizada uma revisão bibliográfica das estratégias e resultados de cerâmicas
(“bulk”) à base de Bi0,5Na0,5TiO3-BaTiO3 (BNT-BT) para aplicações em armazenamento de
energia. Os trabalhos revisados envolveram cerâmicas sintetizadas pelo método de mistura de
óxidos e sinterização convencional. Os dopantes utilizados para melhorias nas propriedades de
armazenamento de energia de cerâmicas à base de BNT-6BT podem ser categorizados dentro de
três grupos principais: metais alcalinos, alcalino-terrosos e terras-raras. O maior valor de
densidade de energia recuperável foi 1.88 J/cm³ obtido com o dopante de metal alcalino-terroso,
SrTiO3, e a maior eficiência foi com o dopante alcalino Na0.73Bi0.09NbO3, 92.5%. As estratégias
empregadas que efetivamente contribuíram para a melhoria nos parâmetros de armazenamento de
energia (densidade de energia recuperável, eficiência, estabilidade térmica, sob fadiga e sob
diferentes frequências de carga-descarga) foram: introdução de vacâncias no sítio A, B, de
oxigênio, indução ao comportamento relaxor-antiferroelétrico e redução do tamanho de grão.
Tais estratégias e o modo de executá-las serão discutidas nesse trabalho de revisão bibliográfica.
The change of the world energy matrix from non-renewable sources to renewable ones is a current trend. This fact has driven the development of energy storage devices, including capacitors. This market is dominated by lead-based ceramics, a highly toxic element for the human health and environment, as well. Thus, several researches have been conducted to develop lead-free based-capacitors that are comparable to those produced with such an element. Dielectrics based on barium titanate and bismuth are the most investigated. In addition, such dielectrics are lighter than those based on lead, which contributes to the reduction of weight in these devices. Performing a J/kg calculation, capacitors based on BNT-BT presenting a recoverable energy density greater than 3.77 J/cm³ become more effective than those based on lead. From this perspective, the study of the strategies and results of ceramics ("bulk") based on Bi0,5Na0,5TiO3-BaTiO3 (BNT-BT) for energy storage applications is demanded. The reviewed works concerning ceramics synthesized by the method of mixing oxides and conventional sintering are presented. The dopants used to improve the energy storage properties of BNT-6BTbased ceramics can be categorized into three main groups: alkaline, alkaline-earth and rare-earth metals. The highest recoverable energy density value obtained was 1.88 J/cm³ with the alkalineearth metal dopant, SrTiO3, and the highest efficiency found was with the alkaline-dope Na0.73Bi0.09NbO3, 92.5%. The better strategies used that effectively contributed to the improvement in energy storage parameters (recoverable energy density, efficiency, thermal stability, under fatigue and under different load-discharge frequencies) were: introduction of vacancies at site A, B, vacancies of oxygen, induction of relaxor-antiferroelectric behavior and reduction of grain size. Such strategies and the way to execute them will be discussed in this bibliographic review.
The change of the world energy matrix from non-renewable sources to renewable ones is a current trend. This fact has driven the development of energy storage devices, including capacitors. This market is dominated by lead-based ceramics, a highly toxic element for the human health and environment, as well. Thus, several researches have been conducted to develop lead-free based-capacitors that are comparable to those produced with such an element. Dielectrics based on barium titanate and bismuth are the most investigated. In addition, such dielectrics are lighter than those based on lead, which contributes to the reduction of weight in these devices. Performing a J/kg calculation, capacitors based on BNT-BT presenting a recoverable energy density greater than 3.77 J/cm³ become more effective than those based on lead. From this perspective, the study of the strategies and results of ceramics ("bulk") based on Bi0,5Na0,5TiO3-BaTiO3 (BNT-BT) for energy storage applications is demanded. The reviewed works concerning ceramics synthesized by the method of mixing oxides and conventional sintering are presented. The dopants used to improve the energy storage properties of BNT-6BTbased ceramics can be categorized into three main groups: alkaline, alkaline-earth and rare-earth metals. The highest recoverable energy density value obtained was 1.88 J/cm³ with the alkalineearth metal dopant, SrTiO3, and the highest efficiency found was with the alkaline-dope Na0.73Bi0.09NbO3, 92.5%. The better strategies used that effectively contributed to the improvement in energy storage parameters (recoverable energy density, efficiency, thermal stability, under fatigue and under different load-discharge frequencies) were: introduction of vacancies at site A, B, vacancies of oxygen, induction of relaxor-antiferroelectric behavior and reduction of grain size. Such strategies and the way to execute them will be discussed in this bibliographic review.
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Citação
Rocha, Yasmim da Silva; Lente, Manuel Henrique. Cerâmicas ferroelétricas à base de BNT-BT para armazenamento de energia. Trabalho de Conclusão de Curso - Engenharia de Materiais. UNIFESP, 2021.