Poly(Alkyl‐Terphenyl Piperidinium) Ionomers and Membranes with an Outstanding Alkaline‐Membrane Fuel‐Cell Performance of 2.58 W cm⁻²

Abstract

Aryl-ether-free anion-exchange ionomers (AEIs) and membranes (AEMs) have become an important benchmark to address the insufficient durability and power-density issues associated with AEM fuel cells (AEMFCs). Here, we present aliphatic chain-containing poly(diphenyl-terphenyl piperidinium) (PDTP) copolymers to reduce the phenyl content and adsorption of AEIs and to increase the mechanical properties of AEMs. Specifically, PDTP AEMs possess excellent mechanical properties (storage modulus>1800 MPa, tensile strength>70 MPa), H₂ fuel-barrier properties (<10 Barrer), good ion conductivity, and ex-situ stability. Meanwhile, PDTP AEIs with low phenyl content and high-water permeability display excellent peak power densities (PPDs). The present AEMFCs reach outstanding PPDs of 2.58 W cm^-2 (>7.6 A cm^-2 current density) and 1.38 W cm^-2 at 80 °C in H₂ /O₂ and H₂ /air, respectively, along with a specific power (PPD/catalyst loading) over 8 W mg^-1 , which is the highest record for Pt-based AEMFCs so far.