Polyethylene Oxide-Coated Electrospun Polyimide Fibrous Seperator for High-Performance Lithium-Ion Battery

A polyethylene oxide (PEO)-coated polyimide (PI) membrane was prepared by electrospinning method followed by a dip-coating and drying process for high-performance lithium-ion batteries (LIB). Semicrystal PEO was covered on the surface of the fibers and partially enmeshed in PI matrix, which formed unique porous structures. The pores with an average size of 4.1 µm and a porosity of 90% served as ion transport channels. Compared with the cell with Celgard 2400 membrane, the half-cell using PEO-coated PI membrane as a separator exhibits excellent electrochemical performance both at room temperature and at low temperature. The electrolyte uptaking rate of PEO-coated PI membrane was 170% and the ionic conductivity was 3.83 × 10–3 S cm–1. PEO-coated PI membrane possessed 5.3 V electrochemical window. The electrode–electrolyte interfacial resistance was 62.4 Ω. The capacity retention ratios with PEO-coated PI membrane were 86.4% at 5 C and 73.5% at 10 C at 25 °C and 75% at 5 C at 0 °C. Furthermore, the cell using the separator demonstrates excellent capacity retention over cycling. These advanced characteristics would boost the application of the PEO-coated PI membrane for high-power lithium ion battery.