Asymmetric Bipolar Membrane for High Current Density Electrodialysis Operation with Exceptional Stability

Creators: Lucas, Éowyn¹; Bui, Justin C.^{2, 3}; Stovall, Timothy Nathan^{2, 3}; Hwang, Monica¹; Wang, Kaiwen¹; Dunn, Emily R.¹; Spickermann, Ellis¹; Shiau, Lily¹; Kusoglu, Ahmet³; Weber, Adam Z.³; Bell, Alexis T.^{2, 3}; Ardo, Shane⁴; Atwater, Harry A.¹; Xiang, Chengxiang¹

1. California Institute of Technology
2. University of California, Berkeley
3. Lawrence Berkeley National Laboratory
4. University of California, Irvine

Abstract

Bipolar membranes (BPMs) enable isolated acidic/alkaline regions in electrochemical devices, facilitating optimized environments for electrochemical separations and catalysis. For economic viability, BPMs must attain stable, high current density operation with low overpotentials in a freestanding configuration. We report an asymmetric, graphene oxide (GrOx)-catalyzed BPM capable of freestanding electrodialysis operation at 1 A cm^–2 with overpotentials <250 mV. Use of a thin anion-exchange layer improves water transport while maintaining near unity Faradaic efficiency for acid and base generation. Voltage stability exceeding 1100 h with an average drift of 70 μV/h at 80 mA cm^–2 and 100 h with an average drift of −300 μV/h at 500 mA cm^–2 and implementation in an electrodialysis stack demonstrate real-world applicability. Continuum modeling reveals that water dissociation in GrOx BPMs is both catalyzed and electric-field enhanced, where low pK_a moieties on GrOx enhance local electric fields and high pK_a moieties serve as active sites for surface-catalyzed water dissociation. These results establish commercially viable BPM electrodialysis and provide fundamental insight to advance design of next-generation devices.

Copyright and License

Acknowledgement

This work (materials development, fabrication, and characterization) was primarily supported as part of United States Department of Energy, Advanced Research Projects Agency–Energy (ARPA-e) under contract number DE-AR0001407 (É.L., M.H., K.W., E.R.D., S.A., H.A.A, C.X.). Computational work was supported by the Liquid Sunlight Alliance, which is supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under award number DE-SC0021266 (J.C.B., E.S., L.S., A.T.B., A.Z.W.). J.C.B. would like to acknowledge support from the National Defense Science and Engineer Graduate Fellowship (NDSEG) supported by the Army Research Office (ARO). T.N.S. and E.R.D. acknowledge support from the National Science Foundation Graduate Research Fellowship (NSFGRFP) under Grant No. DGE 2146752 and No. 2139433, respectively.

Contributions

É.L. and J.C.B. contributed equally. É.L. developed five chamber BPM testing cell, designed and fabricated BPMs, performed electrochemical experiments, characterizations, and data analysis. J.C.B. performed data interpretation, figure development, and all continuum model calculations. T.N.S and fabricated BPMs and porous transport electrodes, performed zero-gap water electrolyzer testing, and T-peel tests. M.H. developed thin cell electrodialysis stack and testing of BPM in the stack. K.W. performed temperature environment simulations and figure development. E.R.D. and E.S. conducted electrodialysis measurements and assisted with reviewer responses and MS/SI updates. L.S. performed XPS measurements. A.K. assisted with T-peel test methods and measurements. A.T.B., A.Z.W., S.A., H.A.A., and C.X. supervised the project. All authors discussed results and participated in the preparation of the manuscript.

Conflict of Interest

The authors declare the following competing financial interest(s): Harry Atwater and CX Xiang are co-founders of Captura Corporation, which has licensed technology reported in this paper.

Supplemental Material

Materials and methods, experimental design and analysis, membrane stability, testing in electrodialysis stack, characterization and analysis of GrOx loading, cell and membrane temperature model, computational methods, additional modeling, titration details, supplemental figures, and water electrolysis data (PDF)

Files

nz4c01662_si_001.pdf

Files (3.8 MB)

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes