The improvement of ionic conductivity, thermal property, as well as cycle performance, is key to promoting the development of lithium-ion batteries (LIBs). Commercial polyolefin-based separators often suffer from low thermal stability and poor electrolyte wettability. Herein, a PVDF-based nanocomposite membrane is prepared by electrospinning and subsequent thermal crosslinking process. The membrane exhibits a highly interconnected macro-porous structure with molecular sieves firmly attaching on it through chemical bonding between particles and synthesized fluorinated copolymer. Molecular sieves with special channel structures and strong Lewis acidity are proposed to contribute to the disassociation of lithium salt and an increase in the lithium ion transport rate. The three-dimensional crosslinked membrane integrates advantages of molecular sieves, copolymer and PVDF, exhibiting near zero contact angle with electrolyte and high electrolyte uptake value of 378%. In addition, the membrane displays fire-resistant property and superior thermal dimensional stability at elevated temperature. The LiFePO<sub>4</sub>/Li cell with the nanocomposite membrane possesses enhanced C-rate capability and excellent cycling performance with capacity retention of 93.8% after 150 cycles at 0.5C. The as-prepared nanocomposite separator is promising as a new kind of separator for advanced LIBs with enhanced electrochemical performance and high safety.

Polymer/molecular sieve hybrid flexible membrane with enhanced thermal and wetting properties for high-performance lithium-ion batteries

256th National Meeting (2018)

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