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DOE OSTI · 1908675

Neutralization Short-Circuiting with Weak Electrolytes Erodes the Efficiency of Bipolar Membranes

Dinh, Hieu Q.·Toh, Wei Lun·Chu, An T.·Surendranath, Yogesh
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Abstract

Bipolar membranes (BPMs) are critical components of a variety of electrochemical energy technologies. Many electrochemical applications require the use of buffers to maintain stable, nonextreme pH environments, yet the impact of buffers or weak acids/bases on the electrochemical behavior of BPMs remains poorly understood. Here, our data for a cell containing weak electrolytes is consistent with internal pH gradients within the anion exchange membrane (AEM) or cation exchange membrane (CEM) component of the BPM that form via ionic short-circuiting processes at open-circuit. Short-circuiting results from the coupling of co-ion crossover and parasitic neutralization and leads to buffering of the bipolar interface. This phenomenon, which we term neutralization short-circuiting, serves to erode BPM efficiency by attenuating the open-circuit membrane voltage and introducing parasitic reverse bias currents associated with weak acid/base dissociation at the interface. These findings establish a mechanistic basis for the operation of BPM cells in the presence of weak acid/base electrolytes.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRYacid and base chemistrybipolar membranesbuffersco-ion crossoverdissociationelectrolytesionic short-circuitingmembranesneutralization short-circuitingpHparasitic neutralizationreverse bias polarizationweak acids/basesweak electrolytes

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Dinh, Hieu Q., Toh, Wei Lun, Chu, An T., Surendranath, Yogesh. 2023-01-12. Neutralization Short-Circuiting with Weak Electrolytes Erodes the Efficiency of Bipolar Membranes. https://doi.org/10.1021/acsami.2c18685

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