Boehmite-coated microporous membrane for enhanced electrochemical performance and dimensional stability of lithium-ion batteries

A heat-resistant boehmite-coated polypropylene (PP) membrane has been successfully fabricated and its potential application as a promising separator in the lithium-ion battery was explored. The boehmite powders with average sizes of 0.78, 1.03, and 1.72 μm, respectively, were used to fabricate the coated membrane. It was demonstrated that the coated membrane prepared by boehmite with a 0.78-μm size showed superior heat tolerance and proper air permeability. As compared to the commercialized PP membrane, such coated membrane presented improved electrolyte uptake, better interface stability, and enhanced ionic conductivity. In addition, the lithium iron phosphate (LiFePO₄)/Li cell using this composite membrane exhibited better rate capability and cycling retention than that using PP membrane owing to its facile ion transport and excellent interfacial compatibility. The coating layer showed an advantage on solid electrolyte interface film formation and greatly reduced charge transfer resistance. All these fascinating characteristics would boost the application of this composite membrane for high-performance lithium-ion battery.