Thermotolerant separators for safe lithium-ion batteries under extreme conditions

Abstract

Lithium-ion batteries are nowadays one of the ultimate energy-storage devices with high power and energy densities. Their thermal-abuse tolerance is needed urgently to meet the safety requirements for hybrid and electric vehicles, especially at elevated temperatures. Separators, while typically regarded as an inactive component, play a crucial role in battery safety and rate capability. Nowadays, in order to meet the safety demands of high-energy-density batteries, thermotolerant separators have become increasingly important for battery design and overall performance. In this review, the strategies and the recent advances in separators for high-safety batteries as well as their uses under extreme conditions are summarized. Several effective routes to thermotolerant separators for lithium-ion batteries are discussed, which include modified polyolefin separators, separators made of thermally stable materials, integration of electrolytes and separators, and smart separators as well. The review provides insights into the design principles of separators to enhance battery performance, and highlights the challenges of emerging energy-storage devices working under extreme conditions of high temperatures.