Ion-specific phenomena limit energy recovery in forward-biased bipolar membranes

Bui, Justin C. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:000000034525957X); Lees, Eric W. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)]; Liu, Andrew K. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000165987254); Toh, Wei Lun [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)] (ORCID:0000000190010488); Stovall, T. Nathan [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); University of California, Berkeley, CA (United States)]; Goyal, Priyamvada [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000198098293); Galang, Francisco U. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000239424623); Surendranath, Yogesh [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)]; Bell, Alexis T. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000257384645); Weber, Adam Z. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000277491624)

doi:10.1038/s44286-024-00154-x

DOE OSTI · 2565274

Ion-specific phenomena limit energy recovery in forward-biased bipolar membranes

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Abstract

The ability for bipolar membranes (BPMs) to interconvert voltage and pH makes them attractive materials for use in energy conversion and storage. Reverse-biased BPMs, which use electrical voltage to dissociate water into acid and base, have become increasingly well studied. However, forward-biased BPMs (FB-BPMs), in which voltage is extracted from pH gradients through recombination, require further study. Here physics-based modeling elucidates how the complex coupling of transport and kinetics dictates the performance of FB-BPMs in electrochemical devices. Simulations reveal that the open-circuit potential of FB-BPMs is dictated by the balance of ion recombination and crossover, where recombination of buffering counter-ions attenuates the open-circuit potential. Counter-ion mass-transport limitations and uptake of ionic impurities limit achievable current densities by reducing the applied pH gradient or the available fixed-charge sites that mediate recombination. Further, the model highlights the importance of selective ion management in mitigating energy losses and provides insight into the rational material design of FB-BPMs for energy applications.

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Bui, Justin C. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:000000034525957X), Lees, Eric W. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Liu, Andrew K. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000165987254), Toh, Wei Lun [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)] (ORCID:0000000190010488), Stovall, T. Nathan [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); University of California, Berkeley, CA (United States)], Goyal, Priyamvada [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000198098293), Galang, Francisco U. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000239424623), Surendranath, Yogesh [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)], Bell, Alexis T. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000257384645), Weber, Adam Z. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000277491624). 2024-12-20. Ion-specific phenomena limit energy recovery in forward-biased bipolar membranes. https://doi.org/10.1038/s44286-024-00154-x

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