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 lowcapacity 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.