A Collaboratively Polar Conductive Interface for Accelerating Polysulfide Redox Conversion.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sulfur cathodes in lithium-sulfur batteries suffer from poor cycle stability due to the dissolution of intermediate lithium polysulfides.
• The shuttle effect of soluble polysulfides leads to capacity fading and reduced battery lifespan.

Purpose of the Study:

• To design a novel host material for sulfur cathodes to improve cycle stability and electrochemical performance.
• To immobilize intermediate lithium polysulfides and mitigate the shuttle effect in lithium-sulfur batteries.

Main Methods:

• Synthesis of a self-assembled SnO2-doped manganese silicate nanobubble (SMN) host.
• Coating SMN with nitrogen-doped carbon (N-C) to form SMN@C composite.
• Electrochemical characterization of S-SMN@C cathodes in lithium-sulfur cells.

Main Results:

• The SMN@C composite effectively immobilizes lithium polysulfides via chemical bonding with oxygen-rich functional groups and heteronitrogen atoms.
• The N-C conductive network accommodates volume expansion and reduces charge transfer resistance (Rct).
• S-SMN@C cathodes exhibit a high initial capacity (1204 mA·h/g at 0.1 C) and excellent cycle stability (0.0277% capacity fading from 2nd to 1000th cycle at 2 C) with 2 mg/cm² sulfur loading.

Conclusions:

• The synergistic effect between N-C and SMN facilitates polysulfide conversion and accelerates redox kinetics.
• The designed SMN@C material significantly enhances the cycle stability and electrochemical performance of lithium-sulfur batteries.
• This approach offers a promising strategy for developing high-performance lithium-sulfur energy storage systems.