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Synergistically integrated phosphonated poly(pentafluorostyrene) for fuel cells

Nature Materials

Lee, Albert S.; Park, Eun J.; Maurya, Sandip; Baca, Ehren B.; Fujimoto, Cy F.; Hibbs, Michael R.; Matanovic, Ivana; Kerres, Jochen; Kim, Yu S.

Modern electrochemical energy conversion devices require more advanced proton conductors for their broad applications. Phosphonated polymers have been proposed as anhydrous proton conductors for fuel cells. However, the anhydride formation of phosphonic acid functional groups lowers proton conductivity and this prevents the use of phosphonated polymers in fuel cell applications. Here, we report a poly(2,3,5,6-tetrafluorostyrene-4-phosphonic acid) that does not undergo anhydride formation and thus maintains protonic conductivity above 200 °C. We use the phosphonated polymer in fuel cell electrodes with an ion-pair coordinated membrane in a membrane electrode assembly. This synergistically integrated fuel cell reached peak power densities of 1,130 mW cm−2 at 160 °C and 1,740 mW cm−2 at 240 °C under H2/O2 conditions, substantially outperforming polybenzimidazole- and metal phosphate-based fuel cells. Our result indicates a pathway towards using phosphonated polymers in high-performance fuel cells under hot and dry operating conditions.

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TYPE Journal Article YEAR 2021
DOIOSTIScopus

Electrode Ionomers for High Temperature Fuel Cells

Hibbs, Michael R.

HT-PEMFCs offer advantages over LT-PEMFCs because of their higher operating temperatures. These advantages include higher catalytic activity, higher tolerance to impurities, and easier thermal management. LANL, in collaboration with SNL, has developed phosphate-quaternary ammonium ionpair coordinated proton exchange membranes for use in HT-PEMFCs. Fuel cells made with the ion-pair membranes have the potential to be operated at temperatures above 200 °C, however there is a tendency for the phosphoric acid to evaporate from the electrodes at temperatures above 180 °C. Thus, there is a need to develop an ionomer that can conduct protons at high temperatures and which can be processed into MEAs. Such a polymer also needs to be extremely durable in order to function at low pH, low RH, high temperature conditions.

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TYPE Other Report YEAR 2018
DOIOSTI
Results 1–25 of 55
Results 1–25 of 55