Bipolar Membrane Polarization Behavior with Systematically Varied Interfacial Areas in the Junction Region

Subarna Kole, Gokul Venugopalan, Deepra Bhattacharya, Le Zhang, John Cheng, Bryan Pivovar, Christopher G. Arges

Research output: Contribution to journalArticlepeer-review

34 Scopus Citations

Abstract

The palette of applications for bipolar membranes (BPMs) has expanded recently beyond electrodialysis as they are now being considered for fuel cell and electrolysis applications. Their deployment in emerging electrochemical technologies arises from the need to have a membrane separator that provides disparate pH environments and to prevent species crossover. Most materials research for BPMs has focused on water dissociation catalysts and less emphasis has been given to the design of the polycation-polyanion interface for improving BPM performance. Here, soft lithography fabricated a series of micropatterned BPMs with precise control over the interfacial area in the bipolar junction. Polarization experiments showed that a 2.28× increase in interfacial area led to a 250 mV reduction in the onset potential. Additionally, the same increase in interfacial area yielded marginal improvements in current density due to the junction region being under kinetics-diffusion control. A simple physics model based on the electric field of the junction region rationalized the reduction in the overpotential for water dissociation as a function of interfacial area. Finally, the soft lithography approach was also conducive for fabricating BPMs with different chemistries ranging from perfluorinated polymer backbones to alkaline stable poly(arylene) hydrocarbon polymers. These polymer chemistries are better suited for fuel cell and electrolysis applications. The BPM featuring the alkaline stable poly(terphenyl) anion exchange membrane had an onset potential of 0.84 V, which was near the thermodynamic limit, and was about 150 mV lower than a commercially available variant.

Original languageAmerican English
Pages (from-to)2223-2238
Number of pages16
JournalJournal of Materials Chemistry A
Volume9
Issue number4
DOIs
StatePublished - 28 Jan 2021

Bibliographical note

Publisher Copyright:
© The Royal Society of Chemistry 2021.

NREL Publication Number

  • NREL/JA-5900-79255

Keywords

  • alkaline fuel cells
  • alkalinity
  • dissociation
  • electric fields
  • electrolysis
  • ion exchange membranes
  • polarization

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