Post-synthetic Covalent Organic Framework to Improve the Performance of Solid-State Li+ Electrolytes

Asa new class of crystalline materials, covalent organic frameworks(COFs) have long-range ordered channels and feasibility to functionalize.The well-arranged pores make it possible to contain and transportions. Here, we designed a novel functionalized anionic COF-SS-Li bya post-synthetic method utilizing the Povarov reaction of BDTA-COF,anchoring -SO3 (-) groups to theCOF backbone and converting the imine linkage to a more stable quinolineunit. The grafted -SO3 (-) groupsand directional channels can promote the lithium-ion transport througha hopping mechanism. As a solid-state lithium-ion electrolyte, COF-SS-Liexhibits the conductivities of 9.63 x 10(-5) Scm(-1) at 20 & DEG;C and 1.28 x 10(-4) S cm(-1) at 40 & DEG;C and a wide electrochemicalwindow of 4.85 V. The assembled Li|COF-SS-Li|Li symmetric cell cancycle stably for 600 h at 0.1 mA cm(-2). Also, theLi|COF-SS-Li|LiFePO4 cell delivers an initial capacityof 117 mAh g(-1) at 0.1 A g(-1) andretains a capacity rate of 56.7% after 500 cycles. The research enrichesthe solid-state electrolytes for lithium-ion batteries.