•Composite electrodes “a-TiSx/TiS2” were designed for all-solid-state batteries.•Conductivity of a-TiSx/TiS2 was higher than that of the a-TiS4.•Capacity of a-TiSx/TiS2 was higher than that of a-TiS4.Composite electrodes composed of amorphous titanium polysulfide (a-TiSx) and titanium disulfide (TiS2) were designed for application in all-solid-state batteries. The conductivity of the a-TiSx/TiS2-based working electrode was higher than that of the amorphous TiS4 (a-TiS4); the reversible capacity of the cell using a-TiSx/TiS2 electrode was higher than that of the cell using a-TiS4. Designing nanocomposite materials such as the a-TiSx/TiS2 described in this paper is an effective way to improve the performance of all-solid-state 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.