Nanofibers versus Nanopores: A Comparison of the Electrochemical Performance of Hierarchically Ordered Porous Carbons

Christian Koczwara, Simon Rumswinkel, Lorenz Hammerschmidt, Miralem Salihovic, Michael S. Elsaesser, Heinz Amenitsch, Oskar Paris, Nicola Huesing

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Two hierarchically organized carbon materials with an inverse mesopore structure were synthesized. Their nanostructure is either composed of hexagonally packed nanofibers (nanocast carbon) or cylindrical nanopores arranged on a hexagonal lattice (soft-templated carbon). Micropores were subsequently introduced by CO2 activation with a concomitant increase in specific surface area. All materials were characterized regarding their structure using electron microscopy, gas adsorption, X-ray diffraction, and small-angle X-ray scattering. Electrochemical characterization was performed employing cyclic voltammetry and electrochemical impedance spectroscopy. It was shown that CO2 activation not only influences the pore structure and specific capacitance but also the rate handling stability for high charging and discharging rates. For short activation times considerable differences in the rate handling capability of the two materials were observed, which are attributed to their entirely different nanostructures and connectivity. For optimum activation parameters, both materials outperform a purely microporous activated carbon reference material in terms of specific capacitance. In terms of rate handling capability, only the nanocast material shows a clearly better performance, while the soft-templated material behaves similarly to the reference. The superior performance of the nanocast material is attributed to an enhanced ion transport mediated by the optimized hierarchical pore structure.

Original languageEnglish
Pages (from-to)5279-5291
Number of pages13
JournalACS Applied Energy Materials
Volume2
Issue number7
DOIs
Publication statusPublished - 22 Jul 2019

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Keywords

  • electrical double-layer capacitor
  • ordered porous carbon
  • rate handling
  • supercapacitor

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Energy Engineering and Power Technology
  • Electrochemistry
  • Materials Chemistry
  • Electrical and Electronic Engineering

Fields of Expertise

  • Advanced Materials Science

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