Streamline Sulfur Redox Reactions to Achieve Efficient Room-Temperature Sodium-Sulfur Batteries

It is vital to dynamically regulate S activity to achieve efficient and stable room-temperature sodium-sulfur (RT/Na-S) batteries. Herein, we report using cobalt sulfide as an electron reservoir to enhance the activity of sulfur cathodes, and simultaneously combining with cobalt single atoms as double-end binding sites for a stable S conversion process. The rationally constructed CoS2 electron reservoir enables the straight reduction of S to short-chain sodium polysulfides (Na2S4) via a streamlined redox path through electron transfer. Meanwhile, cobalt single atoms synergistically work with the electron reservoir to reinforce the streamlined redox path, which immobilize in situ formed long-chain products and catalyze their conversion, thus realizing high S utilization and sustainable cycling stability. The as-developed sulfur cathodes exhibit a superior rate performance of 443 mAh g(-1) at 5 A g(-1) with a high cycling capacity retention of 80 % after 5000 cycles at 5 A g(-1).

Automated summary

It is crucial to regulate S activity dynamically for efficient and stable room-temperature sodium-sulfur (RT/Na-S) batteries. In this study, cobalt sulfide is used as an electron reservoir to enhance the activity of sulfur cathodes, and cobalt single atoms serve as double-end binding sites for stable S conversion. The rational construction of CoS2 electron reservoir enables the direct reduction of S to short-chain sodium polysulfides (Na2S4) through a streamlined redox path. Cobalt single atoms synergistically work with the electron reservoir to reinforce the streamlined redox path, immobilize in situ formed long-chain products, and catalyze their conversion, leading to high S utilization and sustainable cycling stability. The developed sulfur cathodes exhibit superior rate performance and high cycling capacity retention.