RuO_x Quantum Dots Loaded on Graphdiyne for High-Performance Lithium-Sulfur Batteries

Here, a strategy to strengthen d-p orbital hybridization by fabricating π backbonding in the catalyst for efficient lithium polysulfides (LiPSs) conversion is reported. A special interface structure of RuO_x quantum dots (QDs) anchored on graphdiyne (GDY) nanoboxes (RuO_x QDs/GDY) is prepared to enable strong Ru-to-alkyne π backdonation, which effectively regulates the d-electron structures of Ru centers to promote the d-p orbital hybridization between the catalyst and LiPSs and significantly boosts the catalytic performance of RuO_x QDs/GDY. The strong affinity with Li ions and fast Li-ion diffusion of RuO_x QDs/GDY also enable ultrastable Li metal anodes. Thus, S@RuO_x QDs/GDY cathodes exhibit excellent cycling performance under harsh conditions, and Li@RuO_x QDs/GDY anodes show an ultralong cycling life over 8800 h without Li dendrite growth. Lithium-sulfur (Li-S) full cells with S@RuO_x QDs/GDY cathodes and Li@RuO_x QDs/GDY anodes can deliver an impressive areal capacity of 17.8 mA h cm^-2 and good cycling stability under the practical conditions of low negative-to-positive electrode capacity (N/P) ratio (N/P = 1.4), lean electrolyte (E/S = 3 µL mg^-1 ), and high S mass loading (15.4 mg cm^-2 ).