Sulfur Distribution Analysis in Lithium-Sulfur Cathode via Confined Inverse Vulcanization in Carbon Frameworks

Lithium-Sulfur (Li-S) batteries are promising energy storage devices due to their high theoretical energy density. However, challenges such as the shuttling effect and volume expansion have significantly hindered their cycle life and capacity retention. Furthermore, the complex kinetic pathways in Li-S batteries call for advanced characterization techniques to unravel underlying mechanisms. In this study, a hollow porous carbon (HPC) is used as a microreactor, where inverse vulcanization occurs between 1,3-diisopropylbenzene (DIB) and sulfur (S8), resulting in the creation of three-dimensionally interconnected and well-distributed S-DIB in carbon frameworks. As a result, the dual confinement strategy imparts Li-S coin cells with remarkable cycling stability and capacity retention, exhibiting an impressive capacity of 866 mAh g-1 when returning to 0.1 C after 100 cycles of rate capability tests. Particularly, the Energy-selective Backscattered (EsB) assisted Scanning Electron Microscope (SEM) technique as a novel approach is introduced to distinguish different lengths of polysulfides. Their distribution is visualized in the cross-section view of the electrode in a micrometer range. These EsB images provide concrete indications of the sulfur evolution process and explain the capacity degradation during cycling. A hollow carbon framework is used as a microreactor for inverse vulcanization between 1,3-diisopropylbenzene and sulfur. This dual confinement strategy enhances Li-S coin cells' cycling stability and capacity retention. (Poly)sulfide distribution is visualized by Energy selective Backscattered electron imaging (EsB), unraveling the sulfur lithiation and capacity degradation process. image