Enhanced Lithium-Ion Conductivity and Thermal Stability of Al<sub>2</sub>O<sub>3</sub>/Lithiated-Sulfonated-PEEK-Coated Separators for Lithium–Metal Batteries
Seong A. Park, Dongmin Shin, Hyejin Na, Ho Seok Park, Jungdon Suk, Do Youb Kim
Abstract
Lithium–metal batteries (LMBs) have garnered significant interest due to their potential for high-energy-density applications; however, safety concerns arising from lithium (Li) dendrite formation and thermal instability of a conventional polyolefin separator pose critical challenges. In this study, we developed an advanced separator coated with lithiated-sulfonated polyether ether ketone (Li-SPEEK, LSP) and Al 2 O 3 particles to enhance the electrochemical performance and stability of LMBs. The Al 2 O 3 /LSP-coated separator demonstrates improved thermal stability, wettability, and electrolyte uptake compared with bare polyethylene (PE) separators, along with a substantially higher Li + transference number (0.87) and Li + conductivity (0.38 mS/cm). When applied in NCM811//Li cells, the Al 2 O 3 /LSP-coated separator delivers an enhanced rate capability and cycle life, maintaining 77.1% of its initial capacity after 120 cycles. These improvements are attributed to the stabilization of Li growth and suppression of dendrite formation, facilitated by the effective regulation of Li + flux by the Al 2 O 3 particles and the LSP coating layer. This study suggests that Al 2 O 3 /LSP-coated separators present a promising approach to improving the safety and performance of LMBs.