Boehmite-Enhanced PVDF-HFP/PAN Coaxial Electrospun Nanofiber Hybrid Membrane: A Superior Separator for Lithium-Ion Batteries

Abstract

Abstract Polyethylene (PE) and polypropylene (PP) are widely employed in commercial lithium-ion batteries (LIBs) separators due to their superb mechanical strength and chemical stability. Nonetheless, inherent limitations such as inadequate high-temperature resilience, low porosity, and suboptimal wettability curtail their application in high-temperature settings and diminish their lifespan. Creating LIB separators with superior attributes is imperative to attain high electrochemical efficiency. Herein, we engineered nanofibers with a boehmite-modified PVDF-HFP shell and PAN core via electrospinning, subsequently integrating them into an LIB separator. Contrasted with prevailing commercial PP separators, the BM-doped PVDF-HFP/PAN (PAN@PVDF-HFP/BM) membrane showcases a commendable suite of properties, including a heightened shrinkage temperature of 160 o C, impressive porosity at 85.2%, remarkable electrolyte absorption capacity at 872.8%, and stellar ionic conductivity measuring 3.98 mS/cm. An LIB featuring the PAN@PVDF-HFP/BM separator was cycled 200 times at a current rate of 0.2C, revealing minimal specific discharge capacity decay (from 164.9mAhg-1 to 153mAhg-1), and a capacity retention rate of 93.3%. Additionally, the enhancement mechanism of the coaxial nanofiber facilitated by boehmite has been elucidated using Density Functional Theory (DFT) calculations. The PAN@PVDF-HFP/BM nanofiber membrane introduces a pioneering approach to fabricate LIB separators that boast prolonged longevity and high-temperature resilience.