Tuning the ionic and electronic paths in Li2S-based cathode for high-rate performance all-solid-state lithium-sulfur batteries

All-solid-state lithium-sulfur batteries (ASSLSBs) based on sulfur or lithium sulfide (Li2S) as cathodes are one of the most promising candidates for next-generation energy storage devices due to their high theoretical energy density and good safety features. However, despite the promising outlook, the practical application of ASSLSBs is impeded due to the electronically and ionically insulating nature of S and Li2S. Consequently, even with carbon and solid state electrolytes (SSEs) addition, the electron and lithium-ion cannot transport smoothly through the cathode. Therefore, it is imperative to establish and tune effective electron/ion transport paths in the composite cathode to achieve high performance. In the present study, electronically/ionically dual conductive active material Li2S-LiI-MoS2 and high ionically conductive Li6PS5Cl SSE were coupled and modified to control ionic and electronic paths in Li2S-based cathode composite. The optimized composite cathode possessed an overall gravimetric capacity of 423 mAh g-1 at 0.5C and 308 mAh g-1 at 2C with respect to the total mass of the cathode. The corresponding ASSLSBs achieved distinctively high energy with acceptable power density. The indepth analysis by X-ray computed tomography revealed the three-dimensional conductive pathway in the composite cathode.