CoS2@montmorillonite as an efficient separator coating for high-performance lithium-sulfur batteries

The shuttle effect and sluggish redox kinetic of polysulfides still hinder the large-scale application of lithium-sulfur (Li-S) batteries. Herein, we adopt a CoS2-intercalated/coated-montmorillonite (CoS2@montmorillonite) composite to work as an efficient separator coating for improving the performance of Li-S batteries. The polar montmorillonite aluminosilicate sheets can efficiently anchor polysulfides and the well-dispersed nano-micron CoS2 particles can act as electrocatalysts to propel the polysulfide conversion. Furthermore, the modified separator possesses high electrolyte affinity and excellent Li ion transport performance. Consequently, the Li-S cell with the modified separator achieves an outstanding rate performance of up to 7 C (similar to 446 mA h g(-1)) and a high initial specific capacity of 1348 mA h g(-1) at 0.2 C. It also maintains excellent long-term cycling stability for a reversible capacity of 676 mA h g(-1) after 1000 cycles at 2 C with an extremely low decay rate of only 0.025% per cycle. Even with a high sulfur loading of 4.0 mg cm(-2), the cell with the modified separator still delivers satisfactory cycling performance with an areal capacity of 3.41 mA h cm(-2) after 100 cycles at 0.2 C.

Automated summary

By using a modified separator, the performance of lithium-sulfur batteries can be improved, achieving outstanding rate performance and long-term cycling stability.