An integrated solid-state lithium-oxygen battery with highly stable anionic covalent organic frameworks electrolyte

Rechargeable solid-state lithium-oxygen (Li-O2) batteries are considered promising candidates for next-generation energy storage systems. However, the development of solid-state Li-O2 batteries has been limited by the lack of solid-state electrolytes (SSEs) with high ionic conductivities and high stability toward air/metal Li. To address this challenge, we report the three-dimensional covalent organic framework (3D COF) CD-COF-Li with a prominent Li-ion conductivity of 2.7 × 10−3 S cm−1 as the SSE for Li-O2 batteries. The ion transport in the porous COFs is clarified through two-dimensional exchange nuclear magnetic resonance spectroscopy (2D-EXSY NMR), which provides a method at the forefront for understanding Li-ion transport in the molecular channel. Solid-state Li-O2 batteries with CD-COF-Li deliver a high specific capacity (9,340 mAh g−1) and a record cycling life (100 cycles). These findings pave the way for the application of COFs as superior Li-ion conductors in other next-generation solid-state energy storage systems.