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/kgelectrode and 1155 Wh/Lelectrode. 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.