Proton-shuttling nanosheet membranes enable high-power-density protonic fuel cells

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• High-temperature operation is desirable for electrochemical devices but limited by conventional polymer membranes' dehydration and conductivity loss.
• Atomically thin nanosheets offer potential for high-temperature proton conduction via nanoscale features.
• Challenges exist in achieving efficient inter-layer proton transport in stacked nanosheet assemblies.

Purpose of the Study:

• To develop a novel nanosheet-based membrane architecture for anhydrous, high-temperature proton conduction.
• To overcome the limitations of inter-layer proton transport in stacked nanosheet membranes.
• To demonstrate the potential of this architecture in hydrogen fuel cells and methanol tolerance.

Main Methods:

• Fabrication of nanosheet-based membranes by bridging individual nanosheets with nanoconfined phosphoric acid.
• Utilizing a polyethylenimine-functionalized graphene/boron nitride bilayer membrane.
• Testing proton conductivity and fuel cell performance at 250°C under anhydrous conditions.
• Evaluating methanol tolerance of the developed membrane.

Main Results:

• Achieved ultrafast, stable proton conduction under anhydrous high-temperature conditions.
• The developed membrane exhibited a proton conductivity of 166 mS/cm.
• Demonstrated a power density of 1011 mW/cm² in hydrogen fuel cells at 250°C.
• Showcased superior methanol tolerance with a power density of 502 mW/cm² on concentrated methanol.

Conclusions:

• The nanoconfined phosphoric acid bridging architecture enables synergistic proton transport, overcoming inter-layer transport issues.
• The developed membrane significantly outperforms existing anhydrous proton-conducting membranes at high temperatures.
• This work presents a versatile platform for next-generation high-temperature proton-conducting membranes for fuel cells and other electrochemical devices.