Interfacial engineering of polypropylene separator with outstanding high-temperature stability for highly safe and stable lithium-sulfur batteries

Abstract The thermal shrinkage of commercial polypropylene (PP) separator at high temperature seriously restricts the development of safe and stable lithium-sulfur (Li-S) batteries. To address such issue, herein, we present an interfacial engineering strategy by coating conductive polypyrrole (PPY) modified lithium-montmorillonite (PPY/Li-MMT) on the PP separator. The PPY/Li-MMT can service as an effective heat release layer to enhance the high-temperature stability of Li-S batteries. The engineered PP separator exhibits superior performance: it shows nearly no thermal shrinkage even up to 150 °C. Most importantly, the interface engineered separator has not be punctured during the hot piercing testing and the Li-S batteries deliver outstanding thermal stability even at 80 °C. In addition, the PPY/Li-MMT modified PP separator owns very high electrolyte uptake of 348.6%, large ionic conductivity of 3.63 mS cm−1 and stable performance over 600 cycles. This work provides an effective interfacial engineering strategy by coating PPY/Li-MMT interlayer to significantly improve the electrochemical performance and particularly the high-temperature stability of Li-S batteries.