Comb-shaped cationic bridges in phosphoric acid-doped PBI gel membranes: A pathway to flexible and efficient fuel cell operation from −20 °C to 200 °C - Chao Chen; Yan Chen; Bing Zhao; Mingjie Ma; Ningbo Wang; Zheng Li; Yunchu Cheng; Ling Zhou; Congjie Gao; Fei Huang; Lixin Xue (Chemical Engineering Journal, 2025)