Revisiting TiS₂ as a diffusion-dependent cathode with promising energy density for all-solid-state lithium secondary batteries

All-solid-state lithium batteries require a well-designed electrode structure to efficiently charge and discharge active materials. Mimicking electrodes impregnated with liquid electrolyte in lithium-ion batteries, composite-type all-solid-state electrodes have been widely utilized. An alternative electrode configuration is the diffusion-dependent electrode, which consists mostly of active material. Unlike the composite electrode, which uses lithium-ion transport via a percolated solid electrolyte, the diffusion-dependent electrode uses interparticle lithium-ion diffusion through active material particles with a seamless interface. In this design, the energy density dramatically increases owing to the increased content of active material in the electrode. Herein, titanium disulfide (TiS₂) is systematically explored as an appropriate material applicable as a diffusion-dependent cathode owing to its outstanding mechanical and electrochemical properties. Based on the morphology-based study of TiS₂ particles, the diffusion-dependent cathode composed of spherical TiS₂ nanoparticles stably delivers high areal and volumetric capacities of ~ 9.43 mAh/cm² and ~ 578 mAh/cm³, respectively, at a loading level of 45.6 mg/cm², which corresponds to specific energy densities of 414 Wh/kg_electrode and 1155 Wh/L_electrode. The proposed TiS₂ electrode, which can be fabricated by a practical slurry-based process using a conventional binder and solvent, is a strong candidate as a cathode for commercially available all-solid-state lithium batteries.