Zeolitic imidazolate framework-8 derived zinc oxide/ carbon nanofiber as freestanding electrodes for lithium storage in lithium-ion batteries

Zeolitic imidazolate framework-derived carbon and metal oxide composites are promising for applications in lithium-ion batteries due to their morphology and porous structure. Herein, we report freestanding carbon nanofibers grafted with amorphous ZnO where the rhombic dodecahedral morphology of the parent (ZIF8) is maintained. The impacts of ZIF8 loading temperature on particle size after pyrolysis and on the electrochemical properties of these hybrid structures for LIBs are investigated. Polyacrylonitrile nanofiber loaded with ZIF8 at 45 °C exhibits a perfect sodalite topology and optimized particle size. The carbonized freestanding composite fibers have a high specific capacity of 818 mAh·g⁻¹ at a current density of 100 mA·g⁻¹ after 100 cycles. This remarkable performance of ZIF8-derived ZnO is due to its loading and coordination chemistry, which facilitates flexible volume changes and continuity in electrical conductivity through a continuous carbon nanofiber.