Covalent Organic Framework-Based Electrolytes for Fast Li+ Conduction and High-Temperature Solid-State Lithium-Ion Batteries

It has been a long-standing challenge to design and fabricate high Li+ conductive polymer electrolytes at the atomic level with superior thermal stability for solid-state lithium-ion batteries. Covalent organic frameworks (COFs) with tailormade 1D nanochannels provide a potential pathway for fast ion transport, but it remains elusive. In this work, three crystalline thiophene-based imine-linked COFs were constructed and explored as Li+-conducting composite electrolytes by doping ionic liquids into their 1D nanochannels. The COF-IL composite electrolytes exhibited excellent thermal stability (up to 400 degrees C) and high Li+ conductivity (up to 2.60 x 10(-3) S/cm at 120 degrees C, one of the highest values of doped porous organic materials). Furthermore, the COF-IL composite electrolytes exhibited stable cycling in a LiFePO4-Li full cell with a high initial discharge specific capacity of 140.8 mA.h/g at 100 degrees C, more stable than common poly(ethylene oxide)-based electrolytes, indicating great potential application under a high-temperature operation. This work opens a new avenue for the development of fast Li+-conducting COF-based electrolytes for high-temperature solid-state lithium-ion batteries.

Automated summary

This study designed and explored three crystalline thiophene-based imine-linked COFs as Li+-conducting composite electrolytes, demonstrating excellent thermal stability and high Li+ conductivity. The composite electrolytes showed stable cycling performance at high temperatures, indicating great potential for application in high-temperature solid-state lithium-ion batteries.