Designing dendrite resistive poly (ether-ether-ketone) modified multifunctional Celgard separator for lithium metal batteries: Mechanistic and experimental study

Polyolefin membranes are considered promising materials for providing safe and long-term stability for lithium metal batteries (LMBs). However, the practical applicability of LMBs is plagued by various limitations, including lithium dendrite formation, thermal stability, and poor electrolyte compatibility. There is an urgent need to develop multifunctional separators with excellent safety and electrochemical performance benchmarks. In this study, we developed a modified polyolefin separator through a simplified phase inversion method by coating poly (ether-ether-ketone) onto the membrane. Unlike the pristine Celgard separator, the PEEK-modified membrane successfully improved the physical and electrochemical properties of conventional polymeric separators. Theoretical calculations demonstrate that PEEK-modified membranes possess high structural stability and electrolyte affinity, promoting uniform Li⁺ ion flux, facilitating uniform solid electrolyte interface, and preventing dendrite formation. Therefore, the symmetric and full cells using the modified separator exhibit superior electrochemical performance regarding cycling stability and rate capability compared to their original Celgard counterparts. This study may trigger the possibility of designing multifunctional membranes from conventional separators, accelerating the practical implementation of LMBs.