Gel-type polymer separator with higher thermal stability and effective overcharge protection of 4.2 V for secondary lithium-ion batteries

Overcharge protection by electroactive polymer composite separators is an alternative solution for the alleviation of safety concerns of rechargeable Li or Li-ion batteries. The use of gel-type electrolyte with less free organic solvent may benefit the safety performance as well as provide enhanced thermostability. Herein, a kind of gel-type polymer electrolyte separator, prepared by a facile electroactive conducting polymer solution dip-coating method, for effective overcharge protection of Li-ion batteries with enhanced thermal stability and electrochemical safety due to the introduction of heat-resistant polyfluorene end-capped with polysilsesquioxane, may be beneficial for solution of the Li-ion battery safety problem.