Quantifying and elucidating the effect of CO₂ on the thermodynamics, kinetics and charge transport of AEMFCs

Abstract

Exposing operating AEMFCs to CO2 leads to performance-robbing overpotentials, linked to fundamental thermodynamics, transport and kinetics – the impact of which can be reduced through careful systems design and selection of operating conditions.

Effect of reacting gas flowrates and hydration on the carbonation of anion exchange membrane fuel cells in the presence of CO2

“…This third effect was captured quite well in the Gerhardt model [23]. Therefore, the operating voltage for an AEMFC with CO 2 in the cathode feed can be described by Equation (3) 16 :…”

“…Now that AEMFC performance and stability have been enhanced to the point where their future deployment in real applications is realistic, it is an important time in AEMFC development to begin to answer some of the contemporary issues that have to date been mostly put aside in the literature, including operating on real air, which contains CO 2 , leading to the carbonation discussed above. Recently, there have been several experimental [16][17][18][19][20][21] and modeling [22][23][24][25] studies that have allowed researchers in the field to well-understand how adding CO 2 to high performing AEMFCs influences their behavior.…”

“…In total, the voltage loss from these three mechanisms are typically several hundred millivolts under operating conditions of practical interest. The Nernstian voltage loss (ΔV Nernst ) and increase in the charge transfer resistance (iΔR ctHOR ) dominate the CO 2 -related performance loss whereas the voltage loss related to the ASR (iΔASR) increase is often a minor contributor (<10% of the total loss) [16,23].…”

High carbonate ion conductance of a robust PiperION membrane allows industrial current density and conversion in a zero-gap carbon dioxide electrolyzer cell

“…Furthermore, due to the very different operational conditions, new challenges are also faced, among which the presence of CO 2 is the most important one. [25][26][27] By analyzing the anode gas composition during CO 2 reduction, HCO 3 À and CO 3 2À were identified as majority charge carriers responsible for the ion conduction through the AEM (and not OH À such as in water electrolysis), due to the rapid formation of HCO 3 À and CO 3…”

Synthesis of CeOx‐Decorated Pd/C Catalysts by Controlled Surface Reactions for Hydrogen Oxidation in Anion Exchange Membrane Fuel Cells

“…Significant progress has been achieved recently in the field of anion exchange membrane fuel cells (AEMFCs). [1][2][3] In spite of the remarkable development of this technology, the deployment of AEMFCs is still hindered by the chemical degradation of the anion exchange membrane (AEM) and ionomers, [4][5][6][7][8][9][10][11] carbonation issues, [12][13][14][15] and by the sluggish kinetics of the hydrogen oxidation reaction (HOR). [2,16,17] It has been shown that the HOR kinetics in alkaline media is two to three orders of magnitude lower than that in acidic media, [18,19] even for the most active catalysts such as Pt, [17,[19][20][21][22] Rh, [23] and Ir.…”