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/TiO cathodes with sulfur loadings of 1.5 and 3.0 mg cm can deliver reversible discharge capacities of 860 and 659 mA h g 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, its areal capacity reaches 5.2 mA h cm. Such excellent performance is ascribed to the synergy effect of the three-dimension conductive hierarchical pore structure and TiO 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.

Three-dimensional (3D) free-standing nanostructured materials have been proven to be one of the most promising electrodes for energy storage due to their enhanced electrochemical performance. And they are also widely studied for the wearable energy storage systems. In this work, interconnected V6O13 nanosheets were grown on the flexible carbonized textile (c-textile) via a seed-assisted hydrothermal method to form a 3D free-standing electrode for lithium-ion batteries (LIBs). The electrode exhibited a specific capacity of 170 mA h g−1 at a specific current of 300 mA g−1. With carbon nanotube (CNT) coating, its specific capacities further increased 12–40% at the various current rates. It could retain a reversible capacity of 130 mA h g−1, 74% of the initial capacity after 300 cycles at the specific current of 300 mA g−1. It outperformed most of the mixed-valence vanadium oxides. The improved electrochemical performance was ascribed to the synergistic effect of the 3D nanostructure of V6O13 for feasible Li+ diffusion and transport and highly conductive hierarchical conductive network formed by CNT and carbon fiber in c-textile.Electronic supplementary materialThe online version of this article (10.1186/s11671-018-2469-6) contains supplementary material, which is available to authorized users.