The alkaline anion exchange membrane fuel cell (AAEM-FC) is able to deliver a comparable performance to the traditional proton exchange membrane fuel cell (PEM-FC) without the use of precious metal electrocatalysts, making it a more cost-competitive alternative for low-temperature fuel cell applications. However, issues relating to degradation and specifically interaction with CO2 still hinder the technology's commercialisation prospects. With hydration playing a key role in solid polymer electrolyte fuel cell operation, this study examines how membrane hydration affects the AAEM interaction with CO2. The change of membrane conductivity upon exposure to atmospheric CO2 has been compared with the change in viscoelastic properties of a cast thin-film ionomer, both as a function of humidity. The effect of CO2 on the membrane as a function of hydration suggests a link to its solvation and swelling regimes and thus the access of CO2 to the ionic channels within the membrane. The thin-film QCM composite resonator study has suggested that during the solvation (pore opening) regime, there is a linear increase in CO2 uptake as water can further permeate the pore system and the cationic headgroups become increasingly accessible. During the transition to the pore swelling regime, there is a step increase in CO2 uptake as the network is thought to be fully open; as such, subsequent increases in RH do not lead to any significant increase in CO2 uptake.
Bibliographical noteFunding Information:
The authors acknowledge the NPL for supporting Bharath's PhD Studentship and the EPSRC for funding the Electrochemical Innovation Lab's fuel cell research programme through (EP/M014371/1, EP/K038656/1; EP/G060991/1; EP/J001007/1; EP/I037024/1; EP/G030995/1; EP/G04483X/1). PRS acknowledges the Royal Academy of Engineering for funding support.
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Copyright 2017 Elsevier B.V., All rights reserved.
- Alkaline anion exchange membrane
- Carbonate formation
- CO interaction
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Fuel Technology
- Condensed Matter Physics
- Energy Engineering and Power Technology