N-Methylquinuclidinium-Based Anion Exchange Membrane with Ultrahigh Alkaline Stability

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Anion-exchange-membrane (AEM) water electrolysis is a key technology for sustainable hydrogen production.
• Current AEMs suffer from poor stability under harsh alkaline conditions and elevated temperatures, hindering performance.
• Development of robust AEMs is crucial for advancing AEM water electrolysis.

Purpose of the Study:

• To develop a novel AEM with enhanced alkaline stability and comprehensive performance.
• To investigate the potential of a new cationic group, N-methylquinuclidinium, for AEM applications.
• To evaluate the performance of the developed AEM in water electrolysis.

Main Methods:

• Synthesis of a full-carbon chain poly(aryl quinuclidinium) AEM incorporating N-methylquinuclidinium cationic groups.
• Comprehensive stability testing in 10 m NaOH at 80°C for over 1800 hours.
• Characterization of ionic conductivity, dimensional stability, and mechanical properties.
• Performance evaluation in a water electrolyzer with nickel-alloy foam electrodes.

Main Results:

• The novel AEM demonstrated ultrahigh alkaline stability, with no chemical decomposition or conductivity decay.
• Excellent dimensional stability was observed, with low swelling ratios in both pure water and concentrated NaOH.
• High hydroxide conductivity (≈139.1 mS cm⁻¹) and robust mechanical properties were achieved.
• The AEM-based water electrolyzer showed high current density (1.94 A cm⁻² at 2.0 V) and durability.

Conclusions:

• The N-methylquinuclidinium-based AEM exhibits superior comprehensive performance, particularly in alkaline stability.
• This new AEM addresses critical limitations of current materials for efficient and durable hydrogen production.
• The developed AEM holds significant promise for advancing anion-exchange-membrane water electrolysis technology.