Tin sulfide modified separator as an efficient polysulfide trapper for stable cycling performance in Li-S batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries offer high theoretical energy density and low cost, making them promising for next-generation energy storage.
• Key challenges include poor sulfur conductivity and capacity degradation due to the shuttle effect of lithium polysulfides (LiPSs).

Purpose of the Study:

• To investigate the use of a tin-sulfide (SnS2) modified separator to improve the electrochemical performance of Li-S batteries.
• To address the limitations of LiPSs shuttle effect and enhance overall battery capacity and cycling stability.

Main Methods:

• Modification of battery separators with tin-sulfide (SnS2) nanoparticles.
• Electrochemical testing, including capacity measurements, rate capability tests, and long-term cycling.
• Density Functional Theory (DFT) calculations to understand the interaction between SnS2 and LiPSs.

Main Results:

• The SnS2-modified separator demonstrated a high specific capacity of 1300 mA h g⁻¹ at 0.2C, with capacity maintained at 1040 mA h g⁻¹ after 150 cycles.
• Excellent rate capability was achieved, with 700 mA h g⁻¹ at 5C.
• The modified separator showed stable cycling performance up to 500 cycles at 2C with a low decay rate of 0.0710% per cycle.

Conclusions:

• The SnS2 coating effectively confines polysulfides through chemical and physical interactions, improving lithium-ion diffusion and sulfur utilization.
• The modified separator significantly enhances the electrochemical performance, capacity, and cycling stability of Li-S batteries.
• SnS2 is a promising material for developing advanced separators for high-performance Li-S energy storage systems.