Bifunctional separator with sandwich structure for high-performance lithium-sulfur batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries face challenges like the "shuttle effect" and lithium dendrite growth, limiting their practical use.
• These issues stem from polysulfide dissolution and uneven lithium deposition during cycling.

Purpose of the Study:

• To develop a bifunctional separator for Li-S batteries to overcome the shuttle effect and lithium dendrite formation.
• To enhance the cycling stability, rate performance, and safety of Li-S batteries.

Main Methods:

• A facile method was employed to modify a separator with Al2O3 and carbon nanotubes (CNTs).
• The modified separator was used in Li-S battery assembly for performance evaluation.

Main Results:

• The modified Li-S battery demonstrated excellent cycling stability (760.4 mA h/g at 0.2 C after 100 cycles) and promising rate performance.
• The Al2O3 layer effectively interacted with polysulfides, mitigating the shuttle effect.
• CNTs provided high conductivity, improving reaction kinetics and sulfur utilization.
• The composite layers enhanced separator hardness and regulated Li+ ion deposition, preventing dendrite formation and improving safety.

Conclusions:

• The synergistic effect of Al2O3 and CNTs in the bifunctional separator significantly improves Li-S battery performance.
• This approach offers a viable strategy for developing safer and more stable Li-S batteries for energy storage applications.