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Investigation of Charge Transfer Kinetics of Polyaniline Supercapacitor Electrodes by Scanning Electrochemical Microscopy

Authors

  • Afriyanti Sumboja,

    1. School of Materials Science and Engineering, Nanyang Technological University, Singapore
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  • Ushula Mengesha Tefashe,

    1. Carl von Ossietzky University of Oldenburg, Center of Interface Science, Department of Pure and Applied Chemistry, Oldenburg, Germany
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    • Laboratory for Electrochemical Reactive Imaging and Detection of Biological Systems, Department of Chemistry, McGill University, Montreal, QC, Canada, H3A 0G4

  • Gunther Wittstock,

    1. Carl von Ossietzky University of Oldenburg, Center of Interface Science, Department of Pure and Applied Chemistry, Oldenburg, Germany
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  • Pooi See Lee

    Corresponding author
    1. School of Materials Science and Engineering, Nanyang Technological University, Singapore
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Abstract

Scanning Electrochemical Microscopy (SECM) is introduced as a promising technique to probe localized interfacial kinetics at the interface of electrolyte/supercapacitor electrode based on polyaniline (PANI) by measuring approach curves from which heterogeneous charge transfer rate constants (k eff) are extracted. The values correlate with the effectiveness of the electrode material for supercapacitor application. Specifically, measurements on PANI films of different thicknesses show that potential-dependent rate constants are observed only for PANI films of up to 5 μm thickness. In addition to the thickness of PANI, k eff is also found to be affected by the applied potential and surface morphology of PANI electrodes. These findings correlate with the macroscopic electrochemical performance of PANI electrodes which shows enhanced specific charge storage ability when their thickness is below 5 μm. Under these conditions, they deliver a specific capacitance of 486 F g−1 and a rate capability of 89%. The observed correlation between microscopic kinetic data determined by SECM and macroscopic device characteristics provides rational guidelines for the optimization of the physical and structural properties of high performance supercapacitor electrodes.

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