Boosting Battery Safety by Mitigating Thermal‐Induced Crosstalk with a Bi‐Continuous Separator

Abstract Lithium‐ion batteries are taking center stage in the environmental revolution through the ever‐growing adoption of electric vehicles. However, safety issues derived from battery thermal runaway remain a prominent challenge. In this work, a bi‐continuous separator (Bi‐Sep) via micro‐gravure and phase inversion techniques is developed. The proposed nonshrinkage separator exhibits a nanoporous morphology and a super‐stretchable property, thus effectively blocking both internal short circuits and chemical crosstalk between electrodes at thermal abusive temperatures. Besides its considerable performance at normal conditions, the LiNi 0.6 Co 0.2 Mn 0.2 O 2 /graphite pouch cell assembled with the Bi‐Sep separator presents superior sustainability at an elevated temperature of 60 °C. Moreover, the cell using this Bi‐Sep separator achieves an extremely high level of survivability under thermal abusive conditions. This work concludes that engineering the porous structure and thermomechanical properties of a separator, rather than simply improving its heat‐resistance, is of significant importance for the development of safe batteries.