Combining polymeric membranes with inorganic woven fabric: Towards the continuous and affordable fabrication of a multifunctional separator for lithium-ion battery

Abstract

The close relationship between separators and the performances of lithium-ion batteries (LIBs) has motivated considerable R&D passions. However, commercial polyolefin-based separators are often limited by their inferior electrolyte wettability and poor thermal stability, whilst advanced polymeric/inorganic separators are confined in laboratory due to the use of expensive starting materials and complicated manufacture process. Here we report a sandwich separator fabricated by continuously sandwiching a glass fiber fabric with two layers of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) microporous membranes. SiO2 powders are incorporated in the middle layer to improve thermal stability and suppress dendrite growth. The separator inherits not only robust mechanical strength (≥20 MPa) and thermal stability (against both long-term heating and combustion) from inorganic fabric, but also high porosity and electrolyte affinity (electrolyte uptake ~369%) from polymeric membrane, thus possessing extraordinary electrochemical performances. The existence of SiO2 powders further extends the service life of LIB, in that the discharge capacity retains at 157.7 mA hg−1 after 100 cycles at 1.0C. More attractively, fabrication of such separators does not require a tedious procedure or sophisticated equipment, and all materials involved are of affordable price, making us anticipate the great commercial potential of this sandwich separator.