A polyolefin-based hybrid separator for durable and advanced lithium-/sodium-metal batteries

Polyolefin separators are widely used in commercial lithium metal batteries (LMBs). However, their inherent hydrophobic nature causes poor electrolyte uptake and diminished battery performance. And their low melting temperatures eventually led to inevitable dimensional shrinkage at high temperatures, raising the possibility of internal short-circuits that could lead to explosions. In this work, an advanced separator is developed to overcome safety problems and optimize overall performance. By incorporating heat-resistant boehmite (BH) and multipolar self-polymerizing dopamine (DA) into biaxially oriented poly(ethylene) (PE), which allows the separator to promote rapid electrolyte absorption, accelerate Li+/Na+ transference without sacrificing the macrostructure and physiochemical properties of the PE matrix. This hybrid separator possesses excellent thermal stability, and our tests of LMBs cells (Li || LiFePO4) using this hybrid separator demonstrated superior cycle stability compared to commercial polyolefin separators. In addition, the hybrid separator can be used in sodium-metal batteries (NMBs) as well.