Poly(arylene ether nitrile) porous membranes with adjustable pore size for high temperature resistance and high-performance lithium-ion batteries

In this study, flame-retardant poly(arylene ether nitriles) (PEN) porous membranes are prepared by nonsolvent induced phase separation method. Porous PEN membranes with adjustable morphology are obtained by controlling the Hildebrand solubility parameters between non-solvent and PEN. The obtained PEN porous membranes exhibit much higher porosity and electrolyte uptake compare with commercial separators owing to abundant interconnected pore structure in membranes. High thermal stability and flame retardant properties of PEN membrane ensure the high temperature security of lithium batteries. Especially, PEN-IPA membrane with three-dimensional interconnected dendritic network structure shows the best electrolyte affinity and the highest ionic conductivity (1.47 mS/cm). The LFP||Li half cells assembled with the PEN-IPA separator shows outstanding cycle and C rate performance at 85 °C, the discharge capacity retention of the cell was 86% after 100 cycles at 1 C. Our research reveals the role of the cyano groups in the lithium-ion batteries separator and the relationship between morphology and performance of PEN porous membranes for lithium-ion batteries, which provides a facile and effective approach for preparing the promising separators with adjustable pore size, high temperature resistance and high performance for lithium-ion batteries.