We described the design and synthesis of a modified poly(aryl ether ketone) bearing phenolphthalein and allyl groups (P-PAEK) via nucleophilic polycondensation. A new kind of composite separator, crosslinked P-PAEK/polyvinylidene fluoride (c-P-PAEK/PVDF) membrane was successfully prepared using phase separation, phase inversion method, and UV crosslinking technique. As a separator of lithium-ion battery, c-P-PAEK/PVDF membrane demonstrates high porosity and uniform distribution of pores with interconnected pathways. Low thermal shrinkage, distinct shut-down effect, high liquid electrolyte uptake capacity, and exciting liquid electrolyte wettability of the prepared c-P-PAEK/PVDF membrane have been revealed through comprehensive study. Moreover, the c-P-PAEK/PVDF membrane was applied to assemble a conventional Li/LiFePO4 coin cell, which exhibited hopeful cell performance. (C) 2016 Wiley Periodicals, Inc.