Design of Composite Cathodes with High Interfacial Area Density Toward the Use of Non-conductive Active Materials

In contrast to conventional lithium-sulfur batteries facing the fundamental challenge of battery degradation caused by the dissolution of reaction intermediates, it has become evident that utilizing solid electrolytes to construct Li–S batteries in the form of all-solid-state batteries can completely circumvent this issue. Nevertheless, there are still numerous remaining challenges. One of the critical bottlenecks toward high-performance solid-state Li–S batteries is the limitation of carrier transport. The electrochemical utilization of insulating sulfur necessitates intimate compositing with ion and electron-conducting media at a microscopic level. This compositing leads to the miniaturization of constituent components and a drastic increase in interfacial area density, giving rise to unique problems. Among these, the deterioration of macroscopic ionic transport within the composite is particularly severe. This chapter summarizes the current understanding and introduces the quantitative measurement techniques for ionic conduction within composites. At last, the experimental approaches taken to address this critical challenge are showcased.