Vertically Aligned Mesoporous Arrays Catalyzing Long-Chain Polysulfide Conversion to Unlock High-Energy...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Rechargeable magnesium-sulfur (Mg-S) batteries offer high volumetric energy density and safety for energy storage.
• The shuttle effect, caused by unclear origins, severely limits Mg-S battery performance.
• Insufficient MgS8 conversion kinetics is identified as the primary cause of the shuttle effect.

Purpose of the Study:

• To investigate the origins of the shuttle effect in Mg-S batteries.
• To design and synthesize a novel interlayer to modulate sulfur conversion kinetics.
• To improve the electrochemical performance and stability of Mg-S batteries.

Main Methods:

• Fabrication of a metal-organic framework (MOF)-derived cuprous interlayer (Cu-HHTP-200@CNT) with vertically aligned mesoporous arrays.
• Electrochemical characterization of Mg-S batteries with the novel interlayer.
• Analysis of sulfur conversion kinetics and polysulfide shuttle mitigation.

Main Results:

• The Cu-HHTP-200@CNT interlayer effectively modulated sulfur conversion kinetics.
• The shuttle effect was significantly suppressed, leading to an elevated discharge plateau (1.1 to 1.6 V).
• High-rate performance (4090 W kg-1 at 3C after 500 cycles) and low-temperature capacity (236 mAh g-1 at -20°C) were achieved.

Conclusions:

• Insufficient MgS8 conversion kinetics is the primary cause of the shuttle effect in Mg-S batteries.
• The MOF-derived interlayer with catalytic Cu sites effectively regulates sulfur conversion.
• This work provides design principles for high-performance sulfur-based batteries through electrocatalytic regulation.