Batch Preparation and Performance Study of Boehmite-Based Electrospun Nanofiber Separators for Lithium-Ion Batteries

The design and preparation of high-performance separators for lithium-ion batteries (LIBs) have far-reaching practical significance in enhancing the overall performance of LIBs. Electrospun nanofiber separators (ENSs) have the characteristics of large specific surface area, high porosity, small pore size and good affinity with the electrolyte, making them become ideal candidates for LIB separators. In this work, polyacrylonitrile (PAN)/polyurethane (PU) (PAU) ENSs loaded with boehmite (BM) particles (BM/PAU ENSs) were mass-produced using spherical section free surface electrospinning (SSFSE), and used as LIB separators. Their morphology, structures and performances were tested and characterized. The results showed that all BM/PAU ENSs maintained excellent thermal dimensional stability in the range of 140-180 °C, and had good electrolyte wettability and high porosity. The composite BM/PAU-2 ENS with the best performance had a porosity of 52.5%, an electrolyte uptake rate of 822.1%, and an ionic conductivity of 1.97 mS/cm. Additionally, the battery assembled with BM/PAU-2 separator also demonstrated best electrochemical performance, cycling performance, and rate capability, with a capacity retention rate of 94.4% after 80 cycles at 0.5 C, making it a promising high-performance separator for LIBs.