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Desenvolvimento de elétrodos de fibra de carbono modificados para baterias ou supercondensadores
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Abstract(s)
Esta dissertação de mestrado tinha como fundamento a criação de elétrodos de fibra de carbono modificados, para que estes pudessem ser utilizados em baterias e supercondensadores.
Inicialmente, começou-se por experimentar várias configurações físicas e químicas do elétrodo de fibra de carbono, de modo a potenciar ao máximo as qualidades que a fibra de carbono apresenta, nomeadamente a condutividade elétrica, a resistência à corrosão e a estabilidade quando sujeita a altas temperaturas. Para além das propriedades físicas e químicas da fibra de carbono, também é importante salientar que usando este produto para produção de elétrodos, abriria também uma área de negócio para as empresas fornecedoras deste tipo de material, nomeadamente a empresa que facultou bobines de fibra de carbono, a SGL Composites, localizada no Lavradio.
Com o objetivo de tornar a fibra de carbono eletroativa, impregnou-se pequenas porções de fibra com Hexacianoferrato de cobre (II) utilizando material apropriado de laboratório, sendo que de seguida secou-se o recipiente contendo a fibra e a solução numa mufla a 50ºC. Quando o preparado e a fibra estivessem completamente secos, retirava-se a fibra do recipiente, sendo que de seguida lavou-se a fibra com água destilada e secou-se novamente. De seguida lavou-se com KCL 1M e, com a fibra ainda húmida, preparam-se os elétrodos e a célula eletroquímica, passando depois para a execução dos métodos de caracterização dos elétrodos: voltametria cíclica, espectroscopia de impedância eletroquímica, cronopotenciometria e microscopia de varrimento eletrónico.
Após análise cuidada dos resultados, constatou-se que este método de preparação deste tipo de elétrodos poderia ser promissor no que toca à sua aplicação em supercondensadores devido ao seu bom poder de armazenamento de eletricidade, apesar de ter perdido muita capacitância em apenas trinta ciclos, levando assim a que, provavelmente, tivesse de ser estudado um novo método de impregnação. No que toca à sua aplicação a baterias, é necessário um ajuste ao processo de fabricação destes elétrodos pois os resultados obtidos demonstram que não aconteceram reações químicas durantes os ensaios eletroquímicos, que é uma condição fundamental no funcionamento das baterias.
This master’s thesis was aimed at creation of modified carbon fiber electrodes which application would be in batteries or in supercapacitors. Initially, it started to test some physical and chemical configurations of the electrode in order to maximize the good features of carbon fibers, such as electric conductivity, corrosion resistance and high temperature stability. In addiction of the physical and chemical properties of carbon fibers, it’s important to emphasize that building this type of electrodes can open a business market to companies that produces carbon fibers, like SGL Composites, that provided carbon fiber. This company is situated in Lavradio. In order to create an electroactive surface in carbon fiber, it was impregnated small portions of carbon fiber with cupper hexacyanoferrate (II) using laboratory equipment. After the impregnation, the container with the fiber and solution was dried in a muffle at 50ºC. After the drying phase, the impregnated fibers were washed with distillated water and were placed again in the muffle at 50 ºC. After this stage, the impregnated carbon fibers were washed with KCL 1M and, with the fiber still wet, it started to build the electrodes and the electrochemical cell and after this there were tested the analysis to characterize the electrodes: cyclic voltammetry, electrochemical Impedance spectroscopy chronopotentiometry, and scanning electron microscopy, After the results analysis, it is possible to conclude that this type of preparation of the electrodes can be a good way to applicate in supercapacitors, due to the good power in storage electricity, despite having a lot of capacitance in thirty cycles. This fact shows that, probably, a new technique to impregnate the carbon fibers must be studied. In case of applicate this method in batteries, it is necessary to adjust the manufacturing process of this electrodes because the results obtained shows that there were no redox reactions during the electrochemical analysis, and in batteries this type of reactions have to occur.
This master’s thesis was aimed at creation of modified carbon fiber electrodes which application would be in batteries or in supercapacitors. Initially, it started to test some physical and chemical configurations of the electrode in order to maximize the good features of carbon fibers, such as electric conductivity, corrosion resistance and high temperature stability. In addiction of the physical and chemical properties of carbon fibers, it’s important to emphasize that building this type of electrodes can open a business market to companies that produces carbon fibers, like SGL Composites, that provided carbon fiber. This company is situated in Lavradio. In order to create an electroactive surface in carbon fiber, it was impregnated small portions of carbon fiber with cupper hexacyanoferrate (II) using laboratory equipment. After the impregnation, the container with the fiber and solution was dried in a muffle at 50ºC. After the drying phase, the impregnated fibers were washed with distillated water and were placed again in the muffle at 50 ºC. After this stage, the impregnated carbon fibers were washed with KCL 1M and, with the fiber still wet, it started to build the electrodes and the electrochemical cell and after this there were tested the analysis to characterize the electrodes: cyclic voltammetry, electrochemical Impedance spectroscopy chronopotentiometry, and scanning electron microscopy, After the results analysis, it is possible to conclude that this type of preparation of the electrodes can be a good way to applicate in supercapacitors, due to the good power in storage electricity, despite having a lot of capacitance in thirty cycles. This fact shows that, probably, a new technique to impregnate the carbon fibers must be studied. In case of applicate this method in batteries, it is necessary to adjust the manufacturing process of this electrodes because the results obtained shows that there were no redox reactions during the electrochemical analysis, and in batteries this type of reactions have to occur.
Description
Relatório de Dissertação do Mestrado em Engenharia Biológica e Química
Keywords
Fibras de carbono Eletroquímica Supercondensadores Baterias Carbon fibers Electrochemical Supercapacitors Batteries
Citation
Publisher
Instituto Politécnico de Setúbal. Escola Superior de Tecnologia do Barreiro