Synergistically integrated phosphonated poly(pentafluorostyrene) for fuel cells.

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Advanced proton conductors are crucial for electrochemical energy conversion devices like fuel cells.
• Phosphonated polymers are promising anhydrous proton conductors, but anhydride formation limits their conductivity.
• Existing fuel cells face challenges in hot and dry operating conditions.

Purpose of the Study:

• To develop a novel phosphonated polymer that overcomes the limitations of anhydride formation.
• To investigate the performance of this new polymer in fuel cell electrodes.
• To demonstrate high power densities in fuel cells operating at elevated temperatures.

Main Methods:

• Synthesis of poly(2,3,5,6-tetrafluorostyrene-4-phosphonic acid).
• Fabrication of a membrane electrode assembly using the phosphonated polymer in electrodes and an ion-pair coordinated membrane.
• Performance testing of the fuel cell under H2/O2 conditions at various temperatures.

Main Results:

• The developed polymer, poly(2,3,5,6-tetrafluorostyrene-4-phosphonic acid), does not form anhydrides and maintains protonic conductivity above 200°C.
• The integrated fuel cell achieved peak power densities of 1,130 mW cm⁻² at 160°C and 1,740 mW cm⁻² at 240°C.
• Performance significantly surpassed that of polybenzimidazole- and metal phosphate-based fuel cells.

Conclusions:

• The novel phosphonated polymer offers a viable solution for anhydrous proton conduction in fuel cells.
• This material enables high-performance fuel cells capable of operating under hot and dry conditions.
• The findings pave the way for utilizing phosphonated polymers in next-generation fuel cell technologies.