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

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 Al 2 O 3 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 Al 2 O 3 -coated separator can be significantly reduced by employing an eco-friendly water-soluble binder. When the Al 2 O 3 particles are coated onto the PE separator, the reactive Al 2 O 3 -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 Al 2 O 3 -coated separator exhibits stable cycling behavior at 55 °C and excellent thermal safety at 200 °C, demonstrating that the reactive Al 2 O 3 -coated PE is a safer and more reliable separator that ensures good cycling performance and safety. • A reactive Al 2 O 3 -coated separator is prepared using a water-soluble binder. • A reactive separator promotes the in-situ cross-linking of gel precursor in the cell. • The reactive separator exhibits enhanced electrolyte wettability and thermal safety. • The cell with reactive separator exhibits good cycling performance and less leakage. [ABSTRACT FROM AUTHOR]