Effects of different fabrication conditions on the performance of free-standing carbon nanofiber cathodes in lithium–oxygen batteries

This study focuses on the systematic development of free-standing mats consisting of nonwoven carbon nanofibers (CNFs) via electrospinning for a lithium–oxygen battery (LOB) cathode. Electrospun fiber mats prepared using a polyacrylonitrile polymer were carbonized to CNFs at various temperatures ranging from 800 to 1200 °C. The diameter of the CNFs was controlled from 500 to 100 nm. The graphitization degree of the CNFs increased with increasing carbonization temperatures and decreasing CNF diameters and, thus, generated a higher electrical conductivity. The electrochemical performance of CNF cathodes with the different physicochemical properties was systematically evaluated together with close observation of discharge products and gas analyses. The LOB cell using the CNF-100–1200 cathode, with the smallest diameter and highest graphitization degree, exhibited the interesting galvanostatic performance with specific capacity of 7832 mAh/g at 200 mA/g and a cycle stability of 173 cycles with a cut-off capacity of 1000 mAh/g at 500 mA/g among the samples. Graphical abstract