Effects of structure and chemistry on electrochemical transport properties of anion exchange membranes for separation of CO₂

ABSTRACT

The effects of structure, chemistry, and morphology of an anion exchange membrane (AEM) for separation of CO₂ from a humidified gas mixture were characterized to determine the influence on the kinetics and transport properties of a membrane electrode assembly (MEA). Supported and unsupported membranes with thicknesses of 30 µm and 50 µm were used to determine through-plane resistance, ion transport capacity, and gas diffusion properties. The effects of membrane saturation on the membrane resistance was characterized by impedance measurements under conditions with varying relative humidity from 0% to 100%. Permeability measurements with varying CO₂ concentration from 1% CO₂ to 10% CO₂ at temperatures of 25°C and 35°C determined changes in the membrane behavior, which could influence the performance of the CO₂ separating MEA. This study characterized how AEM properties influence the behavior and performance of an electrochemical separating CO₂ MEA suitable for high-humidity, low CO₂ concentration environments. Pt and IrO₂ electrodes were used evaluate the performance of unsupported and supported membranes within a MEA, characterized by electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and constant-current measurements to examine the CO₂ electromigration.

KEYWORDS:

• Anion exchange membrane
• separation
• carbon dioxide
• membrane electrode assembly

Acknowledgements

The authors would like to thank the program sponsors and the support of those at the U.S. Army Combat Capabilities Development Command Chemical Biological Center.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the U.S. Army Combat Capabilities Development Command Chemical Biological Center