Dispersing Agents Impact Performance of Protonated Phosphonic Acid High-Temperature Polymer Electrolyte Membrane Fuel Cells
Jiyoon Jung, Katie Heeyum Lim, Sandip Maurya, Luis Delfin Manriquez, Vladimir Atanasov, Cheol‐Hee Ahn, Seung Sang Hwang, Albert S. Lee, Yu Seung Kim
Abstract
The microstructure of ionomers plays a significant role in the performance of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). Here, we establish direct correlations between the properties of dispersing agents and the microstructure of a protonated phosphonic acid ionomer. Most importantly, the formation of the porous structure of a protonated phosphonic acid ionomer depends on the pKa of the liquid media. Namely, the acid–base interaction between the charged polymer and dispersing agents determines the porosity in the ionomer thin films. The HT-PEMFC performance increases with the level of porosity of the ionomer, as the pores enable fast reactant gas accessibility. This study concludes the importance of the pKa of ionomers’ dispersing media for the HT-PEMFC performance.