Fluorene-containing poly(aryl ketone) membranes with high-density sulfonation and improved stability for proton exchange membrane fuel cells - Qiang Ren; Wenying Li; Liyuan Chen; Ziyu Lin; Hongyu Pan; Zhiwei Zhao; Guannan Chen; Jinhui Pang; Zhewen Liu; Zhenhua Jiang (Chemical Engineering Journal, 2026)