Suppressing the Shuttle Effect in Lithium-Sulfur Batteries by a UiO-66-Modified Polypropylene Separator

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Lithium-sulfur (Li-S) batteries offer high energy density but suffer from the polysulfide shuttle effect.
• This effect, caused by soluble polysulfides migrating to the lithium anode, hinders practical application.
• Separator modification is a key strategy to mitigate the shuttle effect.

Purpose of the Study:

• To functionalize commercial polypropylene separators with a metal-organic framework (MOF), UiO-66.
• To investigate UiO-66 as a physical and chemical barrier against polysulfide migration.
• To improve the cycling stability and performance of Li-S batteries.

Main Methods:

• Functionalization of commercial polypropylene separators with UiO-66 MOF.
• Assembly of Li-S cells using the modified separators.
• Performance evaluation through cycling stability tests at a current rate of 0.5 C for 500 cycles.
• Experimental and theoretical investigations of the MOF-polysulfide interactions.

Main Results:

• Li-S cells with UiO-66 functionalized separators exhibited significantly improved cycling stability.
• An average specific capacity of approximately 720 mA h g^-1 was maintained over 500 cycles.
• UiO-66 demonstrated excellent thermal stability and chemical robustness in various electrolytes and solutions.

Conclusions:

• UiO-66 acts as an effective physical and chemical barrier, suppressing the shuttle effect in Li-S batteries.
• The enhanced cell performance is attributed to both physical restriction and strong chemical interactions between UiO-66 and polysulfides.
• UiO-66 is a highly competitive material for modifying separators in advanced Li-S battery technologies.