Important Role of Ion Flux Regulated by Separators in Lithium Metal Batteries

Polyolefin separators are the most common separators used in rechargeable lithium (Li)-ion batteries. However, the influence of different polyolefin separators on the performance of Li metal batteries (LMBs) has not been well studied. By performing particle injection simulations on the reconstructed three-dimensional pores of different polyethylene separators, it is revealed that the pore structure of the separator has a significant impact on the ion flux distribution, the Li deposition behavior, and consequently, the cycle life of LMBs. It is also discovered that the homogeneity factor of Li-ion toward Li metal electrode is positively correlated to the longevity and reproducibility of LMBs. This work not only emphasizes the importance of the pore structure of polyolefin separators but also provides an economic and effective method to screen favorable separators for LMBs. The three-dimensional pore structures of polyolefin separators have a significant influence on the ion flux distribution towards the lithium (Li) electrode, which consequently causes different Li deposition behavior. It is revealed that an appropriate separator creates a more homogeneous Li ion flux, a more compact deposit Li, and enables Li metal batteries to achieve a longer cycle life. image