Carbon hosts have been utilized to obtain composite cathodes with high sulfur loadings for Li-S batteries. However, the complicated synthesis process may hinder their practical applications. Their mechanical and electrochemical properties shall be further improved. Herein, a facile scalable dip-coating process is developed to synthesize a flexible composite cathode with a high sulfur loading. Via the process, a hybrid composed of carbon nanotubes, carbon black, sulfur, and titania nanoparticles is successfully conformally coated on the carbonized textile (c-textile). The formed flexible c-textile@S/TiO2 cathodes with sulfur loadings of 1.5 and 3.0 mg cm-2 can deliver reversible discharge capacities of 860 and 659 mA h g-1 at 2 C, respectively. For the latter one, it can retain 94% of the initial capacity after 400 cycles with a high Coulombic efficiency (∼96%). When its sulfur loading is further increased to 7.0 mg cm-2, its areal capacity reaches 5.2 mA h cm-2. Such excellent performance is ascribed to the synergy effect of the three-dimension conductive hierarchical pore structure and TiO2 additive. They can physically and chemically entrap the soluble polysulfides in the composite cathode. The as-synthesized free-standing composite electrode is of low cost and a high areal capacity, making it suitable for flexible energy storage applications based on Li-S batteries.
Keywords: carbon nanotube; carbonized textile; dip coating; lithium−sulfur; titania.