Recent advances in lithium-ion battery separators with reversible/irreversible thermal shutdown capability

Currently, advancements in separator technology for lithium-ion batteries (LIBs) have been developed due to their widespread use and key role in ion transportation. Nevertheless, there is still a need for ensuring the operation safety, service life, and user's experience of the batteries. In order to avoid the safety issues caused by the elevating temperature during working process, it is essential to endow separators with thermal shutdown function, which can timely cut off the current and prevent the electrodes from contacting. At the same time, the demand for recycling and sustainability of separators are also growing. Therefore, functional separators with irreversible or reversible thermal shutdown ability came out for future utility and manufacture. In this review, we aim to provide a comprehensive analysis of the technologies employed to enhance the safety of LIBs via highlighting the recent achievements in separators with irreversible thermal protection fabricated by different methods and mechanisms. Moreover, we summarize the intelligent materials that are able to take actions and self-adapt in reversibly thermal protection separators. Current research directions and challenges associated with the use of these LIBs separators and future perspectives in battery thermal protection are also provided. We hope such a review could provide inspiration for the separator researches dedicated on the cyclic utilization, high safety and high performance for future battery developments.