Nanostructured reactive alumina particles coated with water-soluble binder on the polyethylene separator for highly safe lithium-ion batteries

Abstract

The separator and electrolyte are critical to the cycle performance and safety of lithium-ion batteries (LIBs). Selecting a proper combination of separator and electrolyte is thus imperative to develop LIBs that assure long cycle life and enhanced safety. In this work, we deliberately select their good combinations and demonstrate that in-situ thermal cross-linking promoted by reactive Al2O3 particles coated on polyethylene (PE) separator to form the cross-linked network is a potential solution for enhancing both cycling performance and battery safety. The cost for making the reactive Al2O3-coated separator can be significantly reduced by employing an eco-friendly water-soluble binder. When the Al2O3 particles are coated onto the PE separator, the reactive Al2O3-coated separator exhibits enhanced electrolyte wettability and thermal stability. Trimethylolpropane trimethacrylate is chosen as a cross-linking agent and its conversion is investigated by 1H nuclear magnetic resonance (NMR) analysis. The lithium-ion cell assembled with reactive Al2O3-coated separator exhibits stable cycling behavior at 55 °C and excellent thermal safety at 200 °C, demonstrating that the reactive Al2O3-coated PE is a safer and more reliable separator that ensures good cycling performance and safety.