Abstract
Hydroxide-exchange-membrane water electrolysis (HEMWE) is an emerging hydrogen-production pathway that combines many advantages of incumbent alkaline water electrolysis (AWE) and proton-exchange-membrane water electrolysis (PEMWE). Advancement in HEMWE has been accelerated with the development of stable and conductive hydroxide exchange membranes (HEMs) and a more comprehensive understanding of alkaline gas-evolving kinetics. However, performance and durability without supporting electrolytes (SELs) remain inferior to PEMWE and AWE and little is known about the role and impact of the SELs. This study investigates the effects of SELs used as anolyte solutions in HEMWEs including cation-type, anion-type, SEL conductivity and pH, presence of carbonates and increased cation/OH- ratios on cell voltage and stability. We report our findings that (i) cell potential and high-frequency resistance did not correlate with anolyte SEL conductivity, (ii) cation-type influences cell voltage at low current densities (<50 mA cm-2) as predicted by half-cell measurements, (iii) increased cation/OH- ratio causes increased overpotentials, and (iv) carbonates are exchanged in the HEM but removed via self-purging at high current density. Overall, this study concludes that concentrated KOH is still the best SEL.
| Original language | English |
|---|---|
| Article number | 084512 |
| Journal | Journal of the Electrochemical Society |
| Volume | 168 |
| Issue number | 8 |
| DOIs | |
| State | Published - Aug 2021 |
| Externally published | Yes |
Funding
This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, ), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office 89233218CNA000001 DE-AC02-05CH11231 Department of Energy, Advanced Research Projects Agency-Energy DE-AR000688 National Science Foundation DE 1106400 German Fulbright Commission Studienstiftung des Deutschen Volkes https://doi.org/10.13039/501100004350 yes � 2021 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited http://creativecommons.org/licenses/by/4.0/ A.K. gratefully acknowledges funding from the German Fulbright Commission and the Studienstiftung des deutschen Volkes. A.K. thanks the Office for International Education for continuous support during this stay in the US and Prof. Hubert Gasteiger for fruitful discussions. N.D., M.R.G., X.P., A.Z.W., J.F., Y.S.K. and G.A. gratefully acknowledge research support from the HydroGEN Advanced Water Splitting Materials Consortium, established as part of the Energy Materials Network under the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office, under Contract Number DE-AC02–05CH11231 (LBNL) and 89233218CNA000001 (LANL). JCF thanks the National Science Foundation (grant DGE 1106400) for support. S.M., B.Z. and A.S. also acknowledge Advanced Research Projects Agency-Energy under contract DEAR000688. The authors would like to thank Nel Hydrogen for supplying titanium porous transport layers.
| Funders | Funder number |
|---|---|
| German Fulbright Commission | |
| National Science Foundation DE 1106400 German Fulbright Commission Studienstiftung des Deutschen Volkes | |
| Office for International Education | |
| Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office | 89233218CNA000001 DE-AC02-05CH11231 |
| National Science Foundation | DGE 1106400 |
| U.S. Department of Energy | |
| Advanced Research Projects Agency - Energy | DEAR000688 |
| Los Alamos National Laboratory | |
| Studienstiftung des Deutschen Volkes |
