Anewcomposite polymerelectrolyte (CPE) containing aflame-retardant material, Mg(OH)(2), isfabricatedvia a two-step process: porous poly(vinylidene-co-hexafluoropropylene) films composited with different Mg (OH)(2) contents are first prepared via casting and extraction steps, and they are then impregnated with a liquid electrolyte. As the Mg(OH)(2) content in the CPEs increases, their flame-retardant properties are greatly improved compared to those of the bare polymer electrolyte. Moreover, the better wettability of Mg(OH)(2) toward a liquid electrolyte leads to higher ionic conductivities of CPEs, thereby resulting in a better rate capability in LiCoO2/ graphite lithium-ion polymer batteries (LiPBs). However, the Mg(OH)(2) content must be limited to less than 40 wt% to maintain the mechanical properties of the corresponding CPEs. (C) 2017 Elsevier Ltd. All rights reserved.