A Review on Recent Advances, Progressive Design, and Future Challenges of Separators in Lithium‐Ion Batteries

The separator is one of the key inner components in the structure of lithium‐ion batteries (LIBs), which has an important impact on the performance of the batteries. The traditional separators are mainly made from thin‐film and porous polyolefin materials, such as polypropylene (PP), polyethylene (PE), or PP/PE/PP composite separators. With the continuous expansion of the application field of lithium‐ion batteries, the requirements for high‐safety and long‐life separators are becoming higher, which is contributed to the improvement of performance. In this review, the authors firstly gave a detailed introduction to the latest advances in composite separators, including Janus and organic‐inorganic hybrid separators, especially through coating technology to achieve performance improvement. Then, the the types of special separators and related research were introduced, including paper, ceramic, and high‐temperature‐resistant polymer separators. Finally, the challenges and development direction of separators was proposed to provide guidance for practical applications in the high‐power LIBs.