Ionic covalent organic frameworks (COFs) are a class of crystalline materials with stable porous structures, which shows enormous potential for ion transport because of their well-defined nano-channels, especially working as solid-state electrolytes (SSE) materials for Li metal batteries. However, the ionic conductivity of COF SSE is low even directly incorporating additives (e.g., lithium salt), and still is challenging to reach 10–3 S cm–1 at room temperature for the practical All-solid-state Li-metal batteries (ASSLMB) in the absence of organic solvent plasticizers. Herein, we propose a strategy to prepare TpPa-SO3Li-p(BVIm-TFSI) composite SSE with exceptional ionic conductivity of 1.23 x 10–3 S cm–1 at r.t. and a high Li-ion transference number () of 0.82 by incorporating poly(ionic liquid) (PIL) into ionic COFs (iCOFs). Such high conductivity can be explained in two parts. PIL filled the gaps between iCOFs, resulting in decreased contact resistance. Besides, this type of SSE formed Li cation- bis(trifluoromethanesulfonyl)imide (TFSI) anion-Polycation co-coordination structure when lithium salt is introduced into cationic p(BVIm-TFSI). When these composite SEEs are used to assemble Li|SSE|Li symmetric coin cells and Li|SSE|LiCoO2 full coin cells, such a simplified modification achieves good cyclic charge-discharge performance and high stability, which provides a new way to make the next-generation high-safety ASSLMB.

Ionic covalent organic framework and poly(ionic liquid) composite electrolytes for all-solid-state Li-metal batteries

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