This technology is an anion exchange membrane for fuel cells that incorporates long alkyl chains (C6–C20) in a comb-like structure onto the hydrophobic backbone of poly(phenylene oxide) and attaches quaternary ammonium conductive groups. The membrane is formed by imparting anion exchange groups to a polymer that has undergone acylation, reduction, and chloromethylation.
Anion exchange membranes have historically suffered from lower ionic conductivity compared to cation exchange membranes and poor chemical stability under high-temperature alkaline conditions. Increasing the ion exchange capacity (IEC) to boost water content often compromised the membrane's physical properties, sometimes to the point where the membrane structure could not be maintained.
By applying a comb structure to the hydrophobic backbone rather than the hydrophilic conductive groups, this technology increases water content and hydroxide ion conductivity without raising the IEC. It achieves a conductivity of 39–110 mS/cm at 95–100% relative humidity and 20–100°C. The membrane exhibits stable mechanical properties with minimal dimensional change relative to water content, along with improved alkaline stability. Applicable to anion exchange membrane fuel cell separators and battery separators, it ensures consistent ion transport performance across a wide operating temperature range.
This invention was developed with support from the Ministry of Science, ICT and Future Planning for the development of core materials for high-performance anion exchange membranes through molecular structure control.
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