Titanium‐Modified Silicon Oxycarbide as an Efficient Sulfur Host for Lithium–Sulfur Batteries

Research on sulfur hosts that can efficiently anchor lithium polysulfides (LiPSs) is essential to the development of lithium‐sulfur batteries (LSBs). Various host materials have been investigated, including materials that present polar domains that can chemically adsorb LiPSs. Polymer‐derived ceramics (PDCs) can be used as sulfur hosts, as their structure presents regions with carbon and polar domains, which can physically and chemically adsorb LiPSs, respectively, contributing to the capacity retention of LSBs. Here, we investigated the performance of a titanium‐modified silicon oxycarbide (SiOC), referred to as SiTiOC, which consists of a PDC prepared by the crosslinking and pyrolysis of a blended polymer. Thus, sulfur‐impregnated SiTiOC (S@SiTiOC) was investigated as a cathode for LSB cells, which provided stable cycling performance. X‐ray absorption spectroscopy (XAS) at the S K‐edge of post‐cycled S@SiTiOC electrodes in a fully charged state confirmed the oxidation of low‐order LiPSs to high‐order LiPSs. Furthermore, the stability of the sulfur particles present in the S@SiTiOC electrode was directly revealed by operando transmission X‐ray microscopy (TXM), which showed significant sulfur dissolution during the initial discharge, followed by stability. These results indicate that SiTiOC suppressed polysulfide shuttle and sulfur volume expansion, confirming its efficiency as a sulfur host.