Hybrid TiO-TiO2 nanoparticle/B-N co-doped CNFs interlayer for advanced Li S batteries

Abstract

Herein, a novel composite nanofiber, which consists of TiO-TiO2 heterostructure nanoparticles and boron, nitrogen co-doped carbon nanofibers (BNCNF), has been successfully prepared through a facile electrospinning method. Remarkably, as interlayer for LiS batteries, the TiO-TiO2 heterostructure not only enhances the adsorbability of the interlayer to lithium polysulfides (LiPSs) via the Lewis acid-base interactions, but also accelerates the redox reaction kinetics of the LiS batteries dramatically. Moreover, the BNCNF as a flexible framework can remit the volumetric change of the sulfur cathode, physically retard the migration of LiPSs and chemically adsorb to the LiPSs. Attributing to the synergistic effect of TiO-TiO2 nanoparticle and BNCNF membrane, the LiS batteries with the novel composite interlayer (named as TiO-TiO2/BNCNF) exhibit outstanding cycling stability and high discharge capacity, especially at high current density. With the sulfur loading of 2.5 mg cm−2, the cell with the TiO-TiO2/BNCNF interlayer delivers a high initial discharge capacity of 1014.7 mA h g−1 with a decay rate of 0.092% over 400 cycles at 0.5C, and also possesses excellent initial discharge capacity of 650.0 mA h g−1 with a decay rate of 0.068% over 120 cycles even at 2.0C.