Inorganic ceramic fiber separator for electrochemical and safety performance improvement of lithium-ion batteries

A separator based on ceramic fibers with excellent properties, utilized for powerful laminated lithium ion batteries, was prepared by low-cost production process. Physical and chemical characteristics of the separator and the electrochemical as well as the safety performance of lithium ion batteries were extensively investigated, and compared to commercialized polyethylene (PE) and ceramic-coating PE (C-PE) separators. The results demonstrated that inorganic ceramic fiber (CF) membrane exhibited higher porosity (85%), higher electrolyte uptake (381%) and higher ionic conductivity (1.48 mS/cm). Moreover, CF separator did not display thermal shrinkage at 160 °C for 1 h, manifesting that the separator possession of high thermal stability. The lithium nickel cobalt manganese oxide LiNi0.5Co0.2Mn0.3O2/ graphite battery employing the CF membrane displayed superior rate capability, which delivered the discharge capacities of 13.206 A h (0.2 C), 12.729 A h (0.5 C), and 12.074 A h (1 C), respectively. In addition, this battery improved cycle stability, with the capacity retention of 101.4% following 100 cycles at 1 C rate. Results of safety tests presented that batteries with CF separator passed both nail penetration and extrusion tests, implying that the safety performance was remarkably improved. Additionally, CF membrane had only 20 cents in cost for 1 Ah cells, which was ten times lower than commercial PE and C-PE separators. The perfect combination of good properties and low cost made it possible for the CF separator to be a promising separator for laminated lithium-ion batteries, which are especially used in electric vehicles.