Comparison\nof Nanoarchitecture to Porous Media Diffusion\nModels in Reduced Graphene Oxide/Aramid Nanofiber Electrodes for Supercapacitors

Abstract

Structural electrodes\nmade of reduced graphene oxide (rGO) and\naramid nanofiber (ANF) are promising candidates for future structural\nsupercapacitors. In this study, the influence of nanoarchitecture\non the effective ionic diffusivity, porosity, and tortuosity in rGO/ANF\nstructural electrodes is investigated through multiphysics computational\nmodeling. Two specific nanoarchitectures, namely, “house of\ncards” and “layered” structures, are evaluated.\nThe results obtained from nanoarchitecture computational modeling\nare compared to the porous media approach and show that the widely\nused porous electrode theories, such as Bruggeman or Millington–Quirk\nrelations, overestimate the effective diffusion coefficient. Also,\nthe results from nanoarchitecture modeling are validated with experimental\nmeasurements obtained from electrochemical impedance spectroscopy\nand cyclic voltammetry. The effective diffusion coefficients obtained\nfrom nanoarchitectural modeling show better agreement with experimental\nmeasurements. Evaluation of microscopic properties such as porosity,\ntortuosity, and effective diffusivity through both experiment and\nsimulation is essential to understand the material behavior and to\nimprove its performance.