Designing inorganic-organic nanofibrous composite membrane for advanced safe Li-ion capacitors.

In this work, the inorganic-organic nanofibrous composite separators were successfully prepared for Li-ion capacitor (LIC) via wet-laid method using electro-blown spun inorganic alumina (Al 2 O 3) nanofibers and electrospun organic polyimide (PI) nanofibers as components. Benefitting from the synergistic action of fast ions transfer performance and outstanding fire-resistance offered by Al 2 O 3 nanofibers as well as heat-resistance and entangled force derived from PI nanofibers, the novel membranes exhibited excellent film forming property, outstanding flexibility and high ionic conductivity. Moreover, it delivered superior fire-resistance with dimensional stability after burning. It was discovered that the novel membranes prepared with 50 wt% Al 2 O 3 nanofibers showed better ionic conductivity of 2.71 × 10−3 S cm−1 and broader electrochemical stability window of 5.3 V than those of commercial membranes. The LIC assembled with this novel separator reached the energy density of 12.5 Wh kg−1 even at the high power density of 15 kW kg−1. In addition, this LIC presented a high energy density of 57.3 Wh kg−1 at the current density of 0.5 A g−1 and maintained a high cycle stability even after 10,000 cycles. This study provided the design idea and experimental basis for the development of high-performance LIC separator. [ABSTRACT FROM AUTHOR]