Modelagem teórica para melhoramento da eficiência energética em supercapacitores

• Ano de defesa: 2023
• Autor(a) principal: Chagas, Henrique de Araujo
• Orientador(a): Oliveira, Guilherme Colherinhas de
• Banca de defesa: Oliveira, Guilherme Colherinhas de, Castro, Marcos Antonio de, Andrade, Douglas Xavier de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Goiás
• Programa de Pós-Graduação: Programa de Pós-graduação em Fisica (IF)
• Departamento: Instituto de Física - IF (RMG)
• País: Brasil
• Palavras-chave em Português: Dinâmica molecular; Supercapacitor; Grafino; Grafeno; Líquidos iônicos; Eletrólitos; Energia eletroquímica
• Palavras-chave em Inglês: Molecular dynamics; Graphyne; Graphene; Ionic liquids; Electrolytes; Electrochemical energy
• Área do conhecimento CNPq: CIENCIAS EXATAS E DA TERRA::FISICA::FISICA DOS FLUIDOS, FISICA DE PLASMAS E DESCARGAS ELETRICAS::FISICA DE PLASMAS E DESCARGAS ELETRICAS
• Link de acesso: http://repositorio.bc.ufg.br/tede/handle/tede/12790

Two-dimensional carbon materials, such as graphene and graphyne, have stood out in energy storage applications due to their unique physical, chemical, and electronic properties. Graphyne, in particular, presents even more remarkable properties, such as higher specific area, electronic mobility, and intrinsic energy band. Furthermore, biocompatible ionic liquids (ILs), such as those formed by choline and glycine, are increasingly being studied as a less toxic alternative for the environment. This work performed molecular dynamics simulations to investigate the properties of electrolytes based on aqueous mixtures of the biodegradable IL [Ch][Gly] with the IL [Bmim][PF6] as electrolytes in graphyne supercapacitors. Through energetic, structural, and electrostatic analyses, it was possible to describe the Electric Double Layer (EDL) formed near the electrodes. It was found that, although the structure and formation of the EDL are governed by a complex network of electrostatic and van der Waals (vdW) interactions, their interaction with the electrode is dominated by vdW interactions. It was observed that choline-based electrolytes can perform as well as most conventional ILs, but with the advantage of low toxicity. The comparison between graphyne and graphene supercapacitors for the IL mixture revealed a higher capacitance for graphyne, even when comparing similar values for the potential drop. Subsequently, an extensive comparison of electrode performances in energy storage applications under thermodynamic conditions was performed. The electrostatic properties of eight different supercapacitors, four made of graphene and four made of graphyne, in different electrolytes were investigated. A detailed analysis of the energy and organization of the electric charges of these systems is reported for all systems. The results indicate the superiority of the graphyne electrode over the graphene electrodes, confirming previous findings and making graphyne a promising candidate for electrochemical energy storage systems. Thus, this study contributes to the understanding of the properties of two-dimensional carbon materials and their application in energy storage devices.