Ordered Ionic-Liquid Channels Enable Fast Anhydrous Proton Conduction at up to 240°C for Fuel Cells

Area of Science:

• Electrochemistry
• Materials Science
• Nanotechnology

Background:

• Intermediate-temperature electrochemical technologies require high-performance anhydrous proton exchange membranes.
• Existing membranes often struggle with stability and conductivity under anhydrous conditions.

Purpose of the Study:

• To design and demonstrate a novel anhydrous proton exchange membrane with enhanced proton conductivity.
• To investigate the mechanism of proton transport in confined ionic liquid systems.

Main Methods:

• Confinement of ionic liquids (phosphonium-, imidazolium-, sulphonium-based) within 2D channels formed by functionalized boron nitride and graphene nanosheets.
• Fabrication of solid-state composite membranes.
• Characterization of anhydrous proton conductivity and fuel cell performance.

Main Results:

• Achieved stable anhydrous proton conductivities up to 10⁻² S cm⁻¹ at 240°C.
• Demonstrated peak power density of 82 mW cm⁻² in hydrogen-oxygen fuel cells under anhydrous conditions at 240°C.
• Suppressed bulk diffusion of ionic liquid ions, enhancing membrane stability.

Conclusions:

• The proposed strategy of confining ionic liquids within functionalized 2D nanosheet channels offers a robust pathway for high-performance anhydrous proton exchange membranes.
• This approach enables tailored membrane properties for specific electrochemical applications.
• The developed membranes show significant promise for intermediate-temperature fuel cell applications.