TiC nanoparticles supported on free-standing carbon nanofibers enabled high-performance Lithium–Sulfur batteries

Lithium–sulfur (Li–S) batteries hold great promise for substituting current energy-storage technologies owing to their exceptional advantage in energy density. The main challenge in developing practical Li–S batteries is the lack of efficient sulfur host which can simultaneously suppress the shuttle effect and improve the redox kinetics. Polar host materials manifest chemisorptive properties for localizing the mobile polysulfide intermediates, being promising in inhibiting the shuttle effect; however, their poor intrinsic conductivity hinders their role in enhancing the redox kinetics of subsequent conversion reactions. In this regard, a conductive polar host material is highly desirable for efficient and long-life Li–S batteries. Herein, we design and develop a free-standing sulfur host consisted of carbon nanofibers decorated with titanium carbides nanoparticles (TiC/CNFs) for high performance Li–S batteries. Benefiting from the intrinsic chemical polarity and high electric conductivity of TiC, the chemisorption and conversion kinetics of lithium polysulfides are simultaneously promoted, leading to the greatly enhanced battery performance. For example, the S@TiC/CNFs composite cathode retains a high capacity of 672 mA h g−1 after 1000 cycles and an excellent rate performance of 938 mA h g−1 at 5 C. Impressively, even at a super high sulfur loading of 7 mg cm−2, the TiC/CNFs can retain a capacity of 5 mA h (630 mA h g−1) after 100 cycles, highlighting the advantages of the polar conductive sulfur host design for efficient conversion of lithium polysulfides.