Polyethylene (PE) is widely used as a separator material in rechargeable batteries. However, its poor thermal stability restricts proper high-temperature performance and poses safety risks. Additionally, the poor wettability between PE separators and liquid electrolytes limits the rate capability and cycle stability, particularly in high-energy-density lithium-metal batteries (LMBs). To address these challenges, this work reports on strategies involving silica (SiO2)/polydopamine (PDA) coatings on commercial PE separators, allowing enhancement of their electrochemical and thermal properties for LMBs. PDA was predeposited on PE and subsequently directed the in situ sol-gel growth of SiO2, ultimately resulting in a SiO2@PDA-coated PE hybrid separator (SiO2@PDA@PE). PDA furnishes an adhesive catecholamine interlayer for conformal SiO2 nucleation; SiO2 imparts thermomechanical stabilization and homogenizes the ionic flux. Remarkably, incorporation with SiO2@PDA (0.5 wt %, denoted SiO2@PDA@PE-0.5) significantly enhances the separator's ionic conductivity, Li+ transference number, and thermal stability. Consequently, LMBs constructed with a lithium metal anode, LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode, and the SiO2@PDA@PE-0.5 separator demonstrate improved long-term cycle stability (1000 cycles at 72.6% retention rate), high-rate capability (58.1% of 8 C over to 1 C), and high-temperature performance (at 120 °C). This work presents an effective strategy, through separator design, to enhance the electrochemical performance and high-temperature operation of LMBs.
Zhong et al. (Wed,) studied this question.