Enabling High Performance Lithium Metal Battery by Ion-Selective Nanofluidic Transport in a Conjugated Microporous Polymer Protective Layer

Abstract

Lithium metal is the “holy grail” anode needed for unlocking the full potential of cathodes in next generation batteries. However, the use of pure lithium anode faces daunting challenges in terms of safety, cycle life and rate capability. Here, we have developed a solution-processable conjugated microporous thermosetting polymer (CMP) that can be made into 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. As a result, CMP-modified lithium anodes (CMP-Li) exhibit cycle stability of 2550 hours at an areal current density of 20 mA cm−2. Remarkably, 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 using CMP-Li as anode and LiNi0.8Co0.1Mn0.1O2 (NCM811) as cathode exhibits a stable energy density of 400 Wh kg−1.