In-built durable Li–S counterparts from Li–TiS2 batteries

Although lithium-sulfur (Li–S) batteries have attracted lots of attention due to their relatively low cost and high theoretical energy density, the shuttle effect caused by dissolution of lithium polysulfides (Li2Sn) and low conductivity of S/Li2S have hampered the development of this technology. Instead of pure sulfur, TiS2 nanosheets aggregates are synthesized through a facile two-step method and used as the incipient cathode in Li–S batteries, which show high specific capacity and durable cyclic life. Even under an ultra-high charge density of 1 A g−1, the battery can maintain a capacity over 300 mAh g−1 after 1,000 cycles. Experimental results and the first-principles calculations illustrate that the primary capacity contributor gradually changes from TiS2 to Li2S during the long-term cycles due to the tendency of Ti–S bond cleavage and Li–S bond formation, thus the in-built Li–S counterparts take shape from the Li–TiS2 battery. Meanwhile, the emerging Ti atomic layers can act as the current collector, helping the charge transfer for the redox reactions of Li2S. TiS2 nanosheet aggregates synthesized by in situ arc-discharge plasma fabrication of TiH2 precursor followed by after-sulfuration reaction exhibit stable mesoporous structure and novel electrochemical performance. [Display omitted] •Mesoporous TiS2 nanosheet aggregates are synthesized by a facile two-step method.•TiS2 nanosheet aggregates show high specific capacity and durable cyclic life.•Capacity contributors change from TiS2 to Li2S gradually during the long-term cycles.•Maintenance of mesoporous and adsorption of Li2Sn by TiS2 inhibit the shuttle effect.•The in-situ generated Ti can be used as current collector.