A High‐Performance Lithium Metal Battery with Ion‐Selective Nanofluidic Transport in a Conjugated Microporous Polymer Protective Layer

Abstract Lithium metal is the “holy grail” of anodes, capable of unlocking the full potential of cathodes in next‐generation batteries. However, the use of pure lithium anodes faces several challenges in terms of safety, cycle life, and rate capability. Herein, a solution‐processable conjugated microporous thermosetting polymer (CMP) is developed. The CMP can be further converted into a large‐scale membrane with nanofluidic channels (5–6 Å). These channels can serve as facile and selective Li‐ion diffusion pathways on the surfaces of lithium anodes, thereby ensuring stable lithium stripping/plating even at high areal current densities. CMP‐modified lithium anodes (CMP‐Li) exhibit cycle stability of 2550 h at an areal current density of 20 mA cm −2 . Furthermore, CMP is readily amenable to solution‐processing and spray coating, rendering it highly applicable to continuous roll‐to‐roll lithium metal treatment processes. Pouch cells with CMP‐Li as the anode and LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) as the cathode exhibits a stable energy density of 400 Wh kg −1 .