Park, Young Sang Jung, Jiyoon Koo, Mo Beom Kim, Jung Gyu Gu, Jinsuk Choi, Gwan Hyun Kim, Seung Hwan Kim, Jeong F. Ahn, Cheol-Hee Hwang, Seung Sang Chung, Hoon Taek Lee, Albert S. 2025-09-17T02:32:35Z 2025-09-17T02:32:35Z 2025-09-16 2025-10 1385-8947 https://pubs.kist.re.kr/handle/201004/153176 Fuel cells operating at intermediate temperature and low humidity conditions are a potential solution to overcome the drawbacks of both high and low temperature fuel cells for heavy duty transportation applications. Here, we report protonated phosphonic acid membranes that significantly increase the proton conductivity and durability of polymer electrolyte membrane fuel cells operating at intermediate temperatures and low humidity. The protonated phosphonic acid membrane with rigid aromatic polymers is an ideal strategy that utilizes the mixed vehicular and Grotthuss proton hopping ion conduction mechanisms of sulfonated and phosphonic acid polymers to increase proton conductivity and dimensional stability. By applying the protonated phosphonic acid system as both the membrane and ionomeric binder, fuel cell reached peak power densities of 0.51 W cm- 2 at 120 degrees C and 40 % RH without leachable liquid phosphoric acid and demonstrated over 1000 h of onset voltage durability of 30.6 mu V h- 1 at 100 degrees C and 40 % RH conditions vastly outperforming perfluorinated membrane and ionomer combinations. English Elsevier BV All protonated phosphonic acid membrane and ionomers for high powered intermediate temperature proton exchange membrane fuel cells Article 10.1016/j.cej.2025.167336 1 Chemical Engineering Journal, v.522 Chemical Engineering Journal 522 Y scie scopus 001562188800009 2-s2.0-105013546456 Engineering, Environmental Engineering, Chemical Engineering Article HYDROGEN CROSSOVER CHALLENGES CONDUCTION Hydrocarbon membrane Phosphonic acid ionomer Intermediate temperature fuel cell Membrane electrode assembly