Polyketone-Based Anion-Exchange Membranes for Alkaline Water Electrolysis

Area of Science:

• Polymer Chemistry
• Materials Science
• Electrochemistry

Background:

• Anion-exchange membranes (AEMs) are critical components in electrochemical devices like fuel cells and electrolyzers.
• Efficient AEMs typically require robust anion-exchange sites integrated into a stable polymer backbone.
• Developing straightforward and effective AEM preparation methods is essential for technological advancement.

Purpose of the Study:

• To synthesize and characterize novel AEMs based on functionalized aliphatic polyketone.
• To investigate the effect of varying crosslinking degrees on membrane properties.
• To evaluate the performance of the developed AEMs for potential electrochemical applications.

Main Methods:

• Functionalization of aliphatic polyketone with 1-(3-aminopropyl)imidazole via the Paal-Knorr reaction.
• Quaternization of imidazole groups using different alkyl halides (1,4-iodobutane and 1-iodobutane) to control crosslinking.
• Characterization of membrane properties including thermal stability, mechanical strength, and ionic conductivity using techniques like DSC, tensile testing, and electrochemical impedance spectroscopy (EIS).

Main Results:

• Successfully synthesized AEMs with a carbonyl conversion of 33%.
• The membranes exhibited amorphous nature (Tg ~ 30 °C), thermal resistance up to 130 °C, and good mechanical properties (Young's modulus of 372 ± 30 MPa, elongation at break of 86 ± 5%).
• Achieved a maximum ionic conductivity of 9.69 mS/cm, comparable to a commercial AEM (9.66 mS/cm).

Conclusions:

• The developed Paal-Knorr reaction-based functionalization offers a straightforward route to efficient AEMs.
• The synthesized polyketone-based AEMs show promising performance, comparable to commercial standards.
• Further improvements in robustness are needed for widespread application in electrolytic cells.