Impact of crosslinked poly(arylene piperidinium) particles in electrode structures on the performance of anion exchange membrane fuel cells

The electrode's composition and structure, affecting ion-conduction and water uptake and transport, is crucial for polymer electrolyte fuel cells. This study investigates the role of particles versus dispersed ionomer based on poly(arylene piperidinium) (PAP) for AEMFC. Mixed ionomer electrodes, consisting of linear PAP ionomers and crosslinked particles, are synthesized and evaluated in AEMFC single cells through electrochemical characterizations. The addition of insoluble particles corresponding to 5 % of total electrode weight leads to an increase in peak power density of ∼60 % in comparison to when employing electrodes based purely on the linear ionomers such as poly(terphenyl piperidinium) and poly(terphenyl piperidinium- co -trifluoroacetophenone), respectively. A deconvolution of cell resistance contributions based on electrochemical impedance spectroscopy (EIS) data, combined with a distribution of relaxation times analysis (DRT), shows a significant decrease in effective cathode charge transfer resistance. This is attributed to particles serving as bridges between the membrane and the reaction sites, leading to increased ionic conductivity and active site utilization via shortening the distance of water and ion transport through the ionomer phase. In an expansion of the study, PAP particles were added to an electrode sample based on commercial Aemion + ™. A smaller peak power density increase of 27 % was observed, emphasizing the importance of matching the chemical structures of the particles, membrane, and linear ionomer. • The concept of mixed ionomer electrodes was successfully implemented in an AEMFC. • Crosslinked poly(arylene piperidinium) was used as basis for particles and ionomers. • EIS/DRT was applied to deconvolute and quantify resistance contributions. • Performance increase of ca. 60 % could be observed when particles were added. • Particles and ionomers from different polymer types incurred interfacial resistance.