A Freestanding, Dissolution- and Diffusion-Limiting, Flexible Sulfur Electrode Enables High Specific Capacity at High...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Achieving stable, high-areal-capacity sulfur (S) cathodes (>10 mA h cm⁻²) is crucial for high energy density lithium-sulfur (Li-S) batteries.
• Increasing sulfur cathode areal capacity often leads to poor specific capacity and stability due to sulfur dissolution and polysulfide diffusion in thick electrodes.

Purpose of the Study:

• To design a freestanding composite cathode with 3D covalent binding sites and chemical adsorption for enhanced Li-S battery performance.
• To address the challenges of sulfur dissolution and polysulfide migration in high-loading electrodes.

Main Methods:

• Fabrication of a freestanding composite cathode utilizing 3D covalent binding sites and a chemical adsorption environment.
• Electrochemical testing of coin cells and pouch cells with the developed cathode material.
• Evaluation of cycling stability, specific capacity, areal capacity, and flexibility through bending tests.

Main Results:

• The composite cathode demonstrated excellent cycling stability and a specific capacity of 1444.3 mA h g⁻¹ (13 mA h cm⁻²).
• Pouch cells achieved an areal capacity exceeding 11 mA h cm⁻² with a high sulfur loading of 9.00 mg cm⁻².
• The cathode exhibited remarkable flexibility and stability during consecutive bending cycles.

Conclusions:

• The developed freestanding composite cathode effectively limits sulfur dissolution and polysulfide diffusion.
• This architecture enables high-loading, flexible Li-S batteries with exceptional energy density and stability.
• The study provides a foundational strategy for advancing flexible energy storage devices.