Flexible binder-free electrode of porous carbon nanofibers by electrospinning for Li-O2 batteries

Abstract

Free-standing cathodes composed of porous, bendable carbon nanofibers (FCNFs) were fabricated by electrospinning for use in lithium-oxygen (Li-O₂) batteries. By using terephthalic acid (PTA) as the sublimating agent, one-step carbonisation at 1200°C for 2 hours under nitrogen converts the as-prepared samples to have interconnected pores along the FCNFs. Furthermore, the pores with a size of 2-4 µm between the individual FCNFs help prevent electrode clogging during discharge product formation. The physicochemical properties of FCNF were further carefully characterised by scanning electron microscopy (SEM), surface area analysis (BET), transmission electron microscopy (TEM), and Raman spectra (Raman). This strategy makes the FCNFs with a specific surface area of up to 156 m2 g-1, which is significantly higher than the CNFs with 94 m² g^-1. Electrochemical test results exhibited that the FCNFs have a high discharge capacity of 5270 mAh g^-1 at 200 mA g^-1. The cycle life of the Li-O2 battery was also tested, the FCNF electrode showed 262 cycles compared to 73 cycles of the CNF electrode at a limited capacity of 1000 mAh g^-1 and a current density of 500 mA g^-1.