Dr. Yunji Xie is an Assistant Professor at the School of Chemistry, Northeast Normal University, China. He received his bachelor's and master's degrees from Jilin University, where he conducted research on poly(arylene ether)-based proton-exchange membranes for fuel cells under the supervision of Prof. Zhenhua Jiang. He obtained his Ph.D. from the Karlsruhe Institute of Technology (KIT), Germany, in 2023, under the supervision of Prof. Patrick Théato. His doctoral research focused on polymer-based proton- and anion-exchange membranes for fuel cells, as well as gel polymer electrolytes for lithium-metal batteries. His current research interests include the molecular design and synthesis of ion-conducting polymers, the development of polymer-based composite membranes incorporating porous aromatic frameworks (PAFs), and their applications in fuel cells and water electrolysis, with particular emphasis on ion transport, membrane stability, and structure–property relationships.