Sulfophenylated Poly (Ether Ether Ketone Ketone) Nanofiber Composite Separator with Excellent Electrochemical Performance and Dimensional Thermal Stability for Lithium-Ion Battery via Electrospinning

In this investigation, the sulfophenylated poly (ether ether ketone ketone) (SPEEKK) separators for lithium-ion batteries (LIBs) are prepared via electrospinning. The electrospun sulfophenylated poly (ether ether ketone ketone) membranes (es-SP) are then modified with lithium bis(trifuoro-methanesulfonyl)imide (LiTFSI) by immersing in the LiTFSI/ethanol solution to obtain the modified es-SP composite separators (es-SP-Li). SPEEKK displays excellent dimensional thermal stability, and thus the thermal shrinkage of es-SP-Li-20 (20% of LiTFSI in ethanol) composite separators is only 2% after 0.5 h at 200 degrees C. The strong polarity of sulfonic acid groups on SPEEKK and LiTFSI enhances the electrolyte wettability and uptake, and thus afford more Li source, so as to promote the conductivity of lithium ions in the composite separators, which in turn exhibit positive impacts on the rate and cycling stability performance of LIBs. The Li//LiFePO4 cells assembled with es-SP-Li-20 separator demonstrate excellent electrochemical stability over 170 cycles at 0.2 C with a reversible discharge capacity of 153 mAh g(-1), and a promising rate capacity at 2 C. In short, the as-prepared es-SP-Li composite separators with excellent comprehensive property emerge as a promising application in LIBs.