PIM-1 as an artificial solid electrolyte interphase for stable lithium metal anode in high-performance batteries

Lithium metal anode is a promising electrode with high theoretical specific capacity and low electrode potential. However, its unstable interface and low Coulombic efficiency, resulting from the dendritic growth of lithium, limits its commercial application. PIM-1 (PIM: polymer of intrinsic microporosity), which is a polymer with abundant micropores, exhibits high rigidity and flexibility with contorted spiro-centers in the backbone, and is an ideal candidate for artificial solid electrolyte interphases (SEI). In this work, a PIM-1 membrane was synthesized and fabricated as a protective membrane on the surface of an electrode to facilitate the uniform flux of Li ions and act as a stable interface for the lithium plating/stripping process. Nodule-like lithium with rounded edges was observed under the PIM-1 membrane. The Li@PIM-1 electrode delivered a high average Coulombic efficiency (99.7%), excellent cyclability (80% capacity retention rate after 600 cycles at 1 C), and superior rate capability (125.3 mAh g⁻¹ at 10 C). Electrochemical impedance spectrum (EIS) showed that the PIM-1 membrane could lower the diffusion rate of Li⁺ significantly and change the rate-determining step from charge transfer to Li⁺ diffusion. Thus, the PIM-1 membrane is proven to act as an artificial SEI to facilitate uniform and stable deposition of lithium, in favor of obtaining a compact and dense Li-plating pattern. This work extends the application of PIMs in the field of lithium batteries and provides ideas for the construction of artificial SEI.