Free-standing sulfur host based on titanium-dioxide-modified porous-carbon nanofibers for lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries are regarded as a promising next-generation electrical-energy-storage technology due to their low cost and high theoretical energy density. Furthermore, flexible and wearable electronics urgently requires their power sources to be mechanically robust and flexible. However, the effective progress of high-performance, flexible Li-S batteries is still hindered by the poor conductivity of sulfur cathodes and the dissolution of lithium polysulfides as well as the weak mechanical properties of sulfur cathodes. Herein, a new type of flexible porous carbon nanofiber film modified with graphene and ultrafine polar TiO2 nanoparticles is designed as a sulfur host, in which the artful structure enabled the highly efficient dispersion of sulfur for a high capacity and a strong confinement capability of lithium polysulfides, resulting in prolonged cycle life. Thus, the cathode shows an extremely high initial specific discharge capacity of 1501 mA h g−1 at 0.1 C and an excellent rate capability of 668 mA h g−1 at 5 C as well as prolonged cycling stability. The artful design provides a facile method to fabricate high-performance, flexible sulfur cathodes for Li-S batteries