Rationally coupling thermal tolerance, thermal conductance, and overheating-response in a separator for safe batteries


Batteries with increasing energy density have boosted the development of electric vehicles with longer driving ranges but are also arousing safety concerns, especially thermal runaway, which impede their large-scale application. Herein, guided by electro-chemo-thermal process modeling, we reveal the coupled roles of thermal tolerance, thermal conductance, and overheating-response properties of separators in preventing thermal runaway under abusing conditions. As such, we realize the thermal process intensification by integrating these properties into a thermal-managing trilayer separator, by sandwiching a thermal-tolerant poly(p-phenylene benzobisoxazole) matrix between mixture layers of thermal conducting boron nitride nanosheets and overheating-responding polyvinylidene fluoride. Compared with commercial separators, such a separator shows much improved safety performance including nonflammability, anti-shrinkage performance at high temperature (almost zero at 350 °C) and thermal shutdown property, finally doubling safety-responding window for battery management system. The strategy of coupling thermal tolerance, conductance, and overheating-response capability in a separator provides a new venue to intensify the thermal management of batteries and paves up the way for the application of high-safety and high-energy-density batteries.

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