An oxygen-vacancy-boosted heterostructured catalyst with synergistically integrated dual transition-metal oxides for high-performance lithium-sulfur batteries

The practical use of high-energy–density Li–S batteries (LSBs) is significantly hampered by the severe dissolution of soluble Li polysulfides (LiPSs) and their sluggish redox kinetics. To address these issues, a novel heterostructured electrocatalyst comprising nano-RuO₂-decorated hexagonal CeO₂ (NRHC) was developed in this study. The hetero-growth of RuO₂ on the plate-shaped HC induced beneficial oxygen vacancies (OVs), which provided positively charged sites and free electrons owing to the lattice disorder between RuO₂ and CeO₂, thereby boosting the ability of the NRHC to adsorb LiPSs, exhibit enhanced conversion kinetics, and facilitate Li⁺ transport. Moreover, the NRHC heterostructure comprising RuO₂ (a polar but highly conductive material) and CeO₂ (a polar and surface-OV-rich material) effectively improved the “trapping–diffusion–conversion” process to transform LiPSs into Li₂S on its surface. Benefiting from the synergistic catalytic attributes of the NRHC, an LSB with the NRHC-modified separator exhibited superior cyclability (844.7 mAh/g after 1000 cycles with a low-capacity decay rate of 0.029% per cycle) at a high current density of 1 C. Even at a high sulfur loading (6.4 mg cm⁻²), the LSB achieved a high areal capacity of over 4.5 mAh cm⁻² at 0.1 C, highlighting its practical applicability.