Okra-Like Multichannel TiO@NC Fibers Membrane with Spatial and Chemical Restriction on Shuttle-Effect for Lithium–Sulfur Batteries

Abstract

It is especially important to coordinately design the structure and composition of the host in lithium–sulfur batteries (LSBs) for improving its physicochemical adsorption and conversion of lithium polysulfide, which can alleviate the harmful shuttle effect. Herein, a self-supporting multichannel nitrogen-doped carbon fibers membrane embedded with TiO nanoparticles (TiO@NC) was constructed as the electrode for LSBs. The inner channels and the embedded TiO nanoparticles offer spatial confinement and chemical binding for polysulfides, respectively. Moreover, the TiO nanoparticles have abundant oxygen vacancies that promote the conversion of polysulfides. In addition, the nitrogen-doped carbon skeleton can not only serve as highly conductive transportation paths for electrons, but also integrate with the inner channels to sustain the morphology and bear volume expansion during cycling processes. Therefore, the fabricated self-supporting quadruple-channel TiO@NC ultrathin fibers electrode exhibits a high initial specific capacity of 1342.8 mAh g−1 at 0.5 C and high-rate capability of 505.8 mAh g−1 at 4.0 C. In addition, it maintains 696.0 mAh g−1 over 500 cycles with only 0.059% capacity decay per cycle at the high current density of 2.0 C. The multichannel configuration combined with TiO nanoparticles provides a synergetic design strategy for fabricating high-performance electrodes in LSBs. Graphical abstract: The okra-like multichannel TiO@NC membrane has a multiscale synergistic effect on polysulfides to restrict the shuttle effect in lithium–sulfur batteries. In macroscopic, the self-supporting fibers membrane offers a stable conductive network. In microscopic, the multiple channels provide long-range spatial confinement for polysulfides and alleviate volume expansion. In nanoscopic, TiO nanoparticles have chemical binding effect on polysulfides [Figure not available: see fulltext.] Show more