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Material Design Considerations for Bipolar Membranes in Energy Conversion

ORAL

Abstract

Bipolar membranes (BPMs), which consist of a catalyst layer (CL) sandwiched between a cation-exchange membrane (CEM) and an anion-exchange membrane (AEM), possess significant potential for application in energy conversion due to their ability to convert electrical energy into pH gradients by accelerating water dissociation (WD) within their catalytic interface. Unfortunately, the mechanism of WD, and the electrochemical behavior of BPMs, are poorly understood. Advancing understanding of BPM performance is critical to their deployment.

In this talk, we will discuss our recent continuum modeling efforts to understand structure-property-performance relationships in BPMs. We demonstrate that the BPM polarization curve can be broken down into three regimes: a low-current-density regime dominated by salt-ion leakage, an intermediary-current-density regime dominated by the kinetics of WD, and a high-current-density regime controlled by water transport. Modeling reveals that ionomer properties dictate ion leakage and the water limited current density. Meanwhile, the surface properties of the WD catalyst dictate the behavior in the water dissociation regime. The work establishes guidelines for the design of BPMs, setting the stage for BPMs in a wide array of energy technologies.

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Publication: Bui, J. C., Digdaya, I., Xiang, C., Bell, A. T. & Weber, A. Z. Understanding multi-ion transport mechanisms in bipolar membranes. ACS Applied Materials and Interfaces, 12, 52509–52526 (2020). <br>Bui, J. C.*, Corpus, K. R. M., Bell, A. T. & Weber, A. Z.*, On the nature of field enhanced water dissociation catalysis in bipolar membranes. J. Phys. Chem. C, 125, 45, 24974–24987 (2021). Supplementary cover article.<br>Bui, J. C., Lucas, E., Lees, E. W., Xiang, C., Atwater, H. A., Bell, A. T., & Weber, A. Z.* Modeling bipolar membranes for electrochemical carbon capture. In Preparation (2022).<br>Bui, J. C.*, Bell, A. T., & Weber, A. Z.* Elucidating water transport mechanisms in bipolar membranes. In Preparation (2022).

Presenters

  • Justin Bui

    UC Berkeley

Authors

  • Justin Bui

    UC Berkeley

  • Adam Z Weber

    Lawrence Berkeley National Laboratory

  • Alexis T Bell

    University of California, Berkeley