Recent progress of advanced separators for Li-ion batteries

The current state-of-the-art lithium-ion batteries (LIBs) face significant challenges in terms of low energy density, limited durability, and severe safety concerns, which cannot be solved solely by enhancing the performance of electrodes. Separator, a vital component in LIBs, impacts the electrochemical properties and safety of the battery without association with electrochemical reactions. The development of innovative separators to overcome these countered bottlenecks of LIBs is necessitated to rationally design more sustainable and reliable energy storage systems. Therefore, exploitation of advanced separators has emerged as an appealing research trend in laboratory and industry. Here, we review the recent progress made in advanced separators for LIBs, which can be delved into three types: 1. modified polymeric separators; 2. composite separators; and 3. inorganic separators. In addition, we discuss the future challenges and development directions of the advanced separators for next-generation LIBs.