Graduate Research Assistant, Texas A&M University
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“Structural Supercapacitor Electrodes Based on Reduced Functionalized Graphene Oxide”
Structural energy storage devices address both energy storage and structural functionalities in a single unit leading to lighter electric vehicles and more miles between recharging. However, the key challenge is to design electrodes that can simultaneously store energy and bear mechanical loads as these properties come with an inherent trade-off. In this context, here, we demonstrate how selected materials such as reduced graphene oxide (rGO) and aramid nanofibers (ANFs) can be processed into supercapacitor electrodes with enhanced mechanical properties by engineering the interfacial interactions. Recently developed aramid nanofibers, nanoscale Kevlar® fibers, are of great interest due to their exceptional mechanical properties, such as ultimate strength and stiffness. rGO has high electrical conductivity, high surface area, high capacitance, and excellent mechanical properties. ANFs interact with rGO through hydrogen bonding and π-π stacking interactions. To enhance hydrogen bonding interactions, GO was functionalized with -NH2 groups, -COOH groups, dopamine, and tannic acid.
Furthermore, branching the ANFs was investigated. Divalent (Ca2+) and trivalent (Fe3+) ions were introduced to chelate with rGO and further improve the interfacial interactions through coordination bonding. The composite electrodes were fabricated utilizing vacuum-assisted filtration to achieve a nacre-like ‘brick-and-mortar’ structure. The effects of these modifications on the mechanical and energy storage properties are discussed to determine the approach that leads to the best multifunctional performance.
Overall, the enhanced interfacial interactions led to significant improvements in the mechanical performance (up to five-fold increase in Young’s modulus and four-fold increase in tensile strength compared to pure rGO), while maintaining good energy storage performance. This work highlights the importance of chemical interactions for realizing stronger multifunctional materials.
Paraskevi Flouda, Graduate Research Assistant, Texas A&M University
Evi Flouda is a Ph.D. candidate in the Department of Materials Science and Engineering at Texas A&M University working with Professor Lutkenhaus and Professor Lagoudas. In 2016, she received her diploma in materials science and engineering from the University of Ioannina, Greece.
During her undergraduate studies, she worked at the Max Planck Institute for Polymer Research in Germany on the synthesis of hybrid nanoparticles for the catalysis of organic sulfides. Currently, her research focuses on the design and development of structural electrodes for supercapacitors and batteries.
Evi has received several awards for excellence and has served as the internal outreach chair of the Texas A&M Energy Research Society, which organizes the annual TAMU Conference on Energy.