Modelagem teórica para melhoramento da eficiência energética em supercapacitores
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2023-03-01
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Universidade Federal de Goiás
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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.
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CHAGAS, H. A. Modelagem teórica para melhoramento da eficiência energética em supercapacitores. 2023. 86 f. Dissertação (Mestrado em Fisica) - Universidade Federal de Goiás, Goiânia, 2023.