Streamline Sulfur Redox Reactions to Achieve Efficient Room‐Temperature Sodium–Sulfur Batteries. Issue 16 (21st February 2022) - Lei, Yaojie
Abstract: 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 (Na2 S4 ) 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 . Abstract : Engineering CoS2 as electron reservoirs overcomes the limited length of the electron diffusion tunnel over an insulating sulfur cathode and thus achieves fast reaction kinetics in sodium–sulfur batteries. With the assistance of Co1 single atoms, this strategy provides streamlined redox paths, which reduce the formation of unstable polysulfides and enable stable sodium–sulfur batteries.