Porous graphene oxide/carbon nanotube hybrid films as interlayer for lithium-sulfur batteries

Abstract

Highly porous, conductive graphene oxide (GO)/carbon nanotube (CNT) composite films are synthesized via facile vacuum filtration of hybrid dispersion. The flexible film is used as interlayer between separator and sulfur cathode to entrap active materials and prevent polysulfide shuttle. The lithium-sulfur (Li–S) battery furnished with an optimal GO/CNT interlayer delivers an excellent reversible capacity of 671 mA h/g after 300 cycles with a low degradation rate of 0.33 mA h/g or 0.043% per cycle at 0.2C. The encouraging outcome arises from synergistic effects of interlayer characteristics: namely, (i) the porous structure facilitates easy ion transport and electrolyte penetration; (ii) the GO layers with oxygenated functional groups entrap active materials, preventing polysulfide shuttle and enhancing their recycling; and (iii) the highly conductive CNTs offer fast pathways for electron/ion transfer.