Boehmite Nanosheets-coated Separator with Enhanced Performance for Lithium-ion Batteries

It has received extensive attention to modify polyolefin separator by boehmite coating for the improvement of thermal stability and electrolyte wettability, but how to affect the electrochemical performance of the boehmite-coated separators is unclear. In this work, boehmite nanosheets with a mean particle size of 150 nm were synthesized by a simple hydrothermal method, and these nanosheets were coated on the surface of polyethylene (PE) separator by a scraper. The boehmite nanosheet-coated separator has porosity of 46.6%, electrolyte uptake of 138.9%, ionic conductivity of 0.47 mS/cm, and lithium-ion transference number of 0.42. The battery assembled with this separator exhibits good cycling stability, retaining 93.7% discharge specific capacity after 100 cycles at 1C (1C= 150 mA/g). Meanwhile, the boehmite nanosheet-modified separator has a uniformly distributed pore structure, which optimizes the lithium-ion transport flux and suppresses the formation of lithium dendrites.