Open AccessMitigation of Carbon Crossover in CO2 Electrolysis by Use of Bipolar Membranes
Author(s) -
Björn Eriksson,
Tristan Asset,
Francesco Spanu,
Frédéric Lecoeur,
Marc Dupont,
Felipe A. GarcésPineda,
José Ramon Galan Mascaros,
Sara Cavaliere,
Jacqués Rozière,
Frédéric Jaouen
Publication year - 2022
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/ac580e
Subject(s) - anode , electrolysis , chemistry , overpotential , membrane , cathode , selectivity , ion exchange , polymer electrolyte membrane electrolysis , steady state (chemistry) , carbon fibers , analytical chemistry (journal) , inorganic chemistry , chemical engineering , ion , materials science , chromatography , electrode , electrochemistry , electrolyte , organic chemistry , catalysis , biochemistry , composite material , composite number , engineering
The selectivity of CO 2 electrolyzers has hitherto mainly been associated with the cathode selectivity. A few recent studies have shown that the nature of the polymer membrane can impact the system ionic selectivity, with anion exchange membranes (AEM) leading to high crossover of (bi)carbonates during operation and a CO 2 pumping effect. In the present work, we investigate and compare CO 2 crossover during operation through an AEM and a bipolar membrane (BPM) in a flow cell fed with gaseous CO 2 . With AEM, starting with 1 M KHCO 3 catholyte and 1 M KOH anolyte, the anolyte pH rapidly drops from 14 to 8. This triggers an increase of 1.2 V in cell voltage at 45 mA·cm −2 , due to increased OER overpotential and anolyte resistance. Steady-state operation at 45 mA·cm −2 with the AEM results in a CO 2 /O 2 ratio of 3.6 at the anode. With BPM, the anolyte pH decreases more slowly, and the CO 2 /O 2 ratio at the anode under steady-state at 45 mA·cm −2 is only 0.38. Overall, the cell voltage is lower with the BPM than with the AEM at steady-state. These results show the potential of BPMs to mitigate carbon crossover, which could be further reduced by optimizing their design.