TiS2 as an Advanced Conversion Electrode for Sodium-Ion Batteries with Ultra-High Capacity and Long-Cycle Life.

Titanium disulfide (TiS2) is investigated as an advanced conversion electrode for sodium (Na)-ion batteries (NIB) in an ether-based electrolyte (NaPF6/glyme (DME)). The as-prepared TiS2 demonstrates a high reversible capacity of 1040 mA h g-1 at 0.2 A g-1 with the capacity contribution of 521 mA h g-1 in the voltage region below 1.0 V (vs Na/Na+), remarkable initial coulombic efficiency of 95.9% and superior rate capability of 621 mA h g-1 at 40 A g-1. The high conductivity of the Ti-based compounds and nanosized particles generated by chemical conversion reactions could minimize the entropic barrier for the reversible conversion, resulting in high reversibility and ultrafast charge/discharge ability of the electrode. Moreover, with its strong ability to adsorb soluble polysulfide intermediates, the as-prepared TiS2 electrode exhibits superior cycling stability over 9000 cycles, serving as a stable and ultra-high capacity conversion electrode for NIBs.