Anhydrous Proton Conducting Polymer Electrolyte Membranes via Polymerization-Induced Microphase Separation

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid-state polymer electrolyte membranes (PEMs) are critical for next-generation lithium-ion batteries and high-temperature fuel cells.
• Key requirements for these applications include high ionic conductivity, mechanical robustness, and thermal stability.

Purpose of the Study:

• To develop a facile, one-pot synthetic strategy for creating nanostructured PEMs with enhanced properties.
• To incorporate protic ionic liquids into a microphase-separated block copolymer for improved performance.

Main Methods:

• In situ preparation of nanostructured PEMs via polymerization-induced microphase separation.
• Incorporation of a protic ionic liquid into poly(ethylene oxide) domains within a polystyrene/divinylbenzene matrix.
• Characterization of morphology, mechanical properties, thermal stability, and ionic conductivity at elevated temperatures.

Main Results:

• A robust, transparent monolith with a bicontinuous morphology was successfully synthesized.
• The cross-linked polystyrene scaffold provided excellent thermal and mechanical stability, with an elastic modulus of ~10 MPa at 180 °C.
• The membranes achieved an outstanding ionic conductivity of 14 mS/cm at 180 °C due to continuous PEO/protic IL conducting nanochannels.
• Proton conduction via the vehicular mechanism was observed, with a proton transference number of 0.7.

Conclusions:

• The developed one-pot synthesis offers a promising route for high-temperature, robust PEMs with excellent proton conductivities.
• These materials are well-suited for demanding applications in advanced energy storage and conversion devices.
• The combination of mechanical integrity and high ionic conductivity at elevated temperatures represents a significant advancement.