Natural Halloysite Nanotubes Coated Commercial Paper or Waste Newspaper as Highly‐Thermal‐Stable Separator for Lithium‐Ion Batteries

Abstract Commercial polypropylene (PP) and polyethylene (PE) films are widely used as separators for lithium‐ion batteries (LIBs). However, owing to the poor thermal stability of PP and PE films, current LIBs suffer from serious safety risks in their practical applications. As an effective path, the design of novel high‐safety composite separators can significantly overcome the safety issues of LIBs. Herein, a universal and cost‐effective strategy is developed to fabricate highly‐thermal‐stable separators via coating natural halloysite nanotubes (HNTs) on both sides of commercial papers or waste newspaper. The resulted separators show superior properties, including thermal stability, heat conduction, wettability, and electrolyte uptake. Compared with commercial PP separators, both HNTs coated A4 paper and waste newspaper composite separators enable better cycling and rate performance for Li/LiFePO₄ cells. Even after burning in fire or treating under 180 °C, the composite separators still present a normal structure, and the assembled cell can perform as regular. Furthermore, the nail penetration test of pouch cells illustrates that such separator significantly prevents thermal runaway of LIBs. The inexpensive and environmentally friendly materials with a facile coating process provide a highly‐thermal‐stable separator for commercial LIBs.