Amorphous TiS4 positive electrode for lithium–sulfur secondary batteries

• Amorphous titanium polysulfide-acetylene black composite was mechanically prepared.
• Acetylene black was dispersed inside a-TiS4 particles in the composite.
• The composite discharged and charged with a high reversible capacity of 650 mAh g− 1.
• Relatively high coulomb efficiency was achieved by suppressing polysulfide dissolution.

Composite electrodes based on amorphous titanium polysulfide and acetylene black were mechanically prepared, and their performance was investigated. The amorphous TiS4 and acetylene black composites were discharged and charged with a high reversible capacity of 563 mAh g− 1 in the 1.9–3.0 voltage range. The Coulombic efficiency of the composite was higher than that of a sulfur electrode because the dissolution of the polysulfide into electrolytes was suppressed. Amorphization and dispersion of carbon inside the particles were effective in improving the performance of the titanium polysulfide electrodes.