Freestanding polyimide fiber network as thermally safer separator for high-performance Li metal batteries

A stable and high-performance polyimide (PI) fiber mat was prepared via a facile two-step procedure, electrospinning deposition followed by an imidization process. The PI separator presents higher thermal stability (>300 °C) than the commercial polypropylene (PP) (<160 °C). In Li/Cu half-cell configuration, shows long cycle life performance with coulombic efficiency of 82% at 0.5 mA cm–2 after 100 cycles impedance 29 Ω. It also showed suppression sharp Li dendrite growth. While PP delivers poor 24% 99 Ω because formation dendritic Li. Moreover, Li/LiFePO4 full cell exhibits lower polarization charge transfer separator. fibers enhanced electrochemical cells that deliver capacity 118 mAh g−1 C-rate C retention 86% > 99% 200 cycles. Additionally, multimode calorimetry (MMC) studies under in-situ mode revealed freestanding high in cells.