A Sandwich-Structure Composite Membrane as Separator with High Wettability and Thermal Properties for Advanced Lithium-Ion Batteries

摘要

Lithium-ion batteries with high energy density and environmental friendliness have attractedconsiderable interest for reseachers in recent years. However, the conventional polyolefin separatorswith poor electrolyte wettability and low thermal stability limited the further development of lithium-ion batteries. Here we designed a porous poly(m-phenylene isophthalamide) (PMIA) layer, embeddedwith high-dispersed TiO 2 -P(MMA-AA-BA) (TP) nanohybrid, on both sides of a polyethylene (PE)membrane by a facile nonsolvent-induced phase inversion process to improve the electrolyte wettabilityand thermal stability of the PE separator. The TP nanoparticles can disperse uniformly in PMIA layer.Due to the inherent high-heat resistance and good affinity to the liquid electrolyte of PMIA andnanohybrid, this (TP-PMIA)-modified PE (TP-PMIA@PE) membrane exhibits high porosity, high ionicconductivity, improved thermal resistance and superior interfacial stability, which can endow thecomposite membrane-based Li/LiFePO 4 cell with good capacity retention and superior rate capability.The as-prepared composite membrane can serve as a promising separator for high-safety and high-performance lithium-ion batteries.