Dual‐Coated TiO 2 Functionalized Commercial Carbon Cathodes to Enhance the Lithium–Sulfur Battery Performance

Abstract

Lithium–sulfur (Li–S) batteries are among the most promising next-generation energy storage systems due to their high theoretical energy density and low cost. However, their performance is limited by the shuttle effect caused by the dissolution and migration of lithium polysulfides (LiPSs). In previous work, we used sulfurized polyacrylonitrile (SPAN) cathodes with TiO2-based additives to suppress this issue through strong chemical confinement. In this study, we explore the role of TiO2 additives in a more conventional sulfur cathode based on physical confinement, where sulfur is embedded in commercial Super P carbon (C/S). To enhance polysulfide retention, we designed a bilayer cathode architecture by depositing either commercial or synthesized TiO2 as a top layer (cTiO2/C/S and sTiO2/C/S, respectively), using a simple two-step coating method. Compared to the uncoated C/S cathode, TiO2-coated electrodes, particularly sTiO2/C/S, showed improved capacity, enhanced capacity retention and reduced shuttle effects. These improvements are attributed to the stronger chemical affinity between synthesized TiO2 and LiPSs, which effectively limits their diffusion even without covalent bonding. This work demonstrates that polar metal oxide additives like TiO2 can enhance the electrochemical performance of Li–S batteries based on physical sulfur confinement, offering a scalable and practical route for cathode design without relying on complex architectures, expensive current collectors, or additional conductive additives