Engineering the Undercoordinated Edge-Rich Single-Crystal Microreactors for High-Performance Lithium─Sulfur Batteries.

Lithium─sulfur (Li─S) batteries have garnered extensive research interest due to their high theoretical capacity and cost-effectiveness. However, their practical application is hindered by severe shuttle effects and sluggish conversion kinetics. Here, the development of a novel microreactor composed of undercoordinated edge-rich single-crystal nickel─cobalt bimetallic oxides embedded within a conductive carbon nanotube network (NCO/CNT), as an electrocatalyst for Li─S batteries is reported. The single-crystal bimetallic oxide matrix ensures high structural stability during reactions, while its abundant edge sites provide abundant active catalytic centers. Structural analyses reveal pronounced oxygen undercoordination within NCO/CNT, with these unsaturated sites demonstrating strong adsorption and catalytic activity, effectively promoting sulfur species immobilization and conversion. Complementary theoretical calculations indicate that the unique edge-rich undercoordinated design optimizes the electronic configuration of metal atoms, enhancing electron exchange with sulfur species. Benefiting from these features, Li─S batteries incorporating NCO/CNT achieve an initial discharge capacity of 1327.1 mAh g at 0.2C, and a high areal capacity of 5.4 mAh cm under a sulfur loading of 5.83 mg cm, with 96.3% capacity retention after 50 cycles. This work offers insights into the design of high-performance sulfur microreactors, paving the way for efficient and sustainable sulfur electrochemistry.