Oxygen Etching‑Derived Semi‑Embedded TiO2 Nanoparticles for Superior Polysulfide Confinement and Catalytic Conversion.

Lithium-sulfur (Li‑S) batteries are promising as next‑generation high‑energy‑density storage systems, yet their practical application is hindered by the polysulfide shuttle effect and sluggish conversion kinetics. Herein, we report an innovative partial oxygen etching strategy, that achieves semi‑embedding of TiO2 nanoparticles within the porous carbon channels by partially removing the carbon at a specific temperature (TiO2@C‑500). Within this unique architecture, the semi‑embedded TiO2 nanoparticles offer abundant active sites for polysulfide chemisorption and accelerated sulfur conversion kinetics, while the microporous carbon network functions as both an effective physical barrier against the shuttle effect and a fast electron conduction pathway. Moreover, the coupling interaction of TiO2 nanoparticles with the carbon layer reinforces structural stability, ensuring durable and efficient catalysis over extended operation. Consequently, Li‑S batteries assembled with the TiO2@C‑500 modified separator deliver an initial discharge capacity of 1434 mAh g-1 at 0.1 C and exhibit a low capacity decay rate of 0.049% per cycle during long‑term cycling at 1 C. Furthermore, a high areal capacity of 9.6 mAh cm-2 is achieved even under a demanding sulfur loading of 8.34 mg cm-2. In summary, this work ingeniously designs a semi‑embedded TiO2@C structure, delivers a major breakthrough in Li‑S batteries, thereby establishing a new design paradigm.