Zeolitic imidazolate framework-7 textile-derived nanocomposite fibers as freestanding supercapacitor electrodes

Zeolitic imidazole frameworks (ZIFs) are a class of metal organic frameworks (MOFs) with diverse energy-related applications. High-surface area materials derived from ZIFs can serve as electrodes with good long-term capacity retention. Herein, we demonstrate an electrospun ZIF7/carbon nanofiber (CNF) derived nanocomposite as a freestanding electrode for supercapacitors with excellent capacitance retention. The optimal ZIF7 composite nanofiber carbonized at 950 °C exhibited a specific capacitance of 202 F·g−1 at a current density of 1 A·g−1 and ~98% specific capacitance retention after 5000 charge-discharge cycles. N-doped nanoporous C and the Zn framework of ZIF7 composite fibers delivered an energy density of 42 W·h·kg−1 at a power density of 0.6 kW·kg−1. These scalable ZIF7/CNF composite textiles (30 × 10 cm2) can be used as freestanding supercapacitor electrodes without a separate substrate or current collector.