Hydrophobic Quaternized Poly(fluorene) Ionomers for Emerging Fuel Cells

Quaternized polymers as electrode ionomeric binders enable fuel cell operation under high-pH or anhydrous conditions. Herein we report quaternized poly(fluorene) ionomers with controlled hydrophobicity (contact angle of electrodes with the ionomers 109–164°) by changing the length of tethered fluoroalkyl chains. The anion-exchange membrane fuel cell employing the hydrophobic ionomer exhibits improved durability (voltage loss 0.41 mV h–1) through better water management. The high-temperature proton-exchange-membrane fuel cell using the ionomer shows superior H2/air performance (1.7 A cm–2 at 0.4 V). The finding in this study highlights the benefits of hydrophobic ionomers for emerging fuel cell applications.