Multilayer composite nanofibrous film accelerates the Li⁺diffusion for quasi-solid-state lithium-ion batteries

The rational design of dense and flexible solid-state electrolytes (SSEs) with interface compatibility is still challenging. Here, we report a three-layer dense 3D nanofibrous matrix (PCOF) by constructing a nanofiber framework combining polyacrylonitrile (PAN) and fast Li-ion conductor covalent organic frameworks (COFs) by electrospinning method. PCOF film can maintain an extraordinary electrolyte/electrode interface and an interconnected ion-conduction pathway, accelerating Li+ diffusion. The PCOF quasi-solid-state electrolyte (QSSE) has high oxidative stability (4.70 V, versus Li+/Li) and ion conductivity of 2.94×10-4 S cm-1 at room temperature. Lithium-ion battery based on PCOF QSSE with LiFPO4 (LFP) cathode exhibits outstanding rate characteristics and cycling stability. This multi-layer composite strategy will start a new area of QSSEs lithium-ion electrolytic devices, and simultaneously accelerate the design of electrolytes featuring a wide range of properties.