Ashley Hoffmaster1 Megan Sassin1 Jeffrey Long1 Chi Kin Lo2 Anna Österholm2 John Reynolds2

1, Naval Research Laboratory, Washington, District of Columbia, United States
2, Georgia Institute of Technology, Atlanta, Georgia, United States

Conducting polymers (CPs) have been extensively investigated as prospective charge-storage materials for electrochemical capacitors. However, the methods typically used to fabricate CP-based electrodes (e.g., electrodeposition for 2D thin-film electrodes or solution-based synthesis followed by processing into composite-electrode formulations) severely limit their footprint-normalized capacity and rate performance, hindering their technological relevance. As an alternative, Reynolds and co-workers recently developed synthetic methods that yield gram-scale quantities of solution-processable CPs based on ProDOT and EDOT.[i],[ii] The ability to solubilize these CP variants makes them amenable to incorporation into advanced 3D electrode architectures. We demonstrate scalable solution-based deposition methods to incorporate these CPs as conformal thin films at loadings of ≥ 30 wt.% throughout macroscopically thick 3D carbon-paper electrodes. The resulting 3D electrode design maintains the inherently fast charge-storage kinetics of the CP, yet greatly enhances the footprint-normalized capacitance by a factor of 120, from 0.4 mF cm-2 for the 2D thin film to 48 mF cm-2 for the 3D electrode. To demonstrate the technological relevance of these CP-3D carbon paper electrodes, we assess their rate-dependent capacitance/capacity, self-discharge, and cycle life in two terminal devices.

[i]. Ponder Jr., J. F.; Österholm, A. M.; Reynolds, J. R. “Designing a Soluble PEDOT Analogue without Surfactants or Dispersants,” Macromolecules 49, 2106 (2016).

[ii]. Österholm, A. M.; Ponder Jr., J. F.; Kerszulis, J. A.; Reynolds, J. R., “Solution Processed PEDOT Analogues in Electrochemical Supercapacitors,” ACS Appl. Mater. Interfaces 8, 13492 (2016).