Structural energy and power systems offer both mechanical and electrochemical performance in a single multifunctional platform. These are of growing interest because they potentially offer reduction in mass and/or volume for aircraft, satellites, and ground transportation. The long-term vision is to combine the mechanical properties of structural composites with the energy storage properties of batteries or capacitors. However, there is a natural tradeoff between mechanical and energy storage properties, such that it remains difficult to synergistically optimize both. To this end, flexible graphene-based supercapacitors have attracted much attention due to their extraordinary mechanical and electrical properties, yet they suffer from poor strength. This problem may be exacerbated with the inclusion of functional guest materials, often yielding strengths of less than 15 MPa. Here, we show that reduced graphene oxide paper supercapacitor electrodes containing aramid nanofibers as guest materials exhibit extraordinarily high tensile strength (100.6 MPa) and excellent electrochemical stability (Kwon, S. et al. ACS Nano 11 (7), 6682-6690 (2017)). This is achieved by extensive hydrogen-bonding and π-π interactions between the reduced graphene oxide sheets and aramid nanofibers. Aramid nanofibers are the nanoscale version of Kevlar, which is known for its exceptional mechanical properties and use in bullet-proof vests. The tradeoff between capacitance and mechanical properties is evaluated as a function of aramid nanofiber loading, where it is shown that these electrodes exhibit multifunctionality superior to that of other reduced graphene oxide-based supercapacitors. We anticipate these composite electrodes to be a starting point for structural energy and power systems that harness the mechanical properties of aramid nanofibers. Our future work, which includes an informatics-driven assessment of the system as well as functionalization effects of the reduced graphene oxide sheets will also be discussed.

Reduced graphene oxide: Aramid nanofiber capacitors for structural energy and power

2019 Spring National Meeting

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