Solid Carbon Spheres with Interconnected Open Pore Channels Enabling High-Efficient Polysulfide Conversion for...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Hollow or core-sheath porous carbon spheres are common in lithium-sulfur (Li-S) battery cathodes.
• Existing structures can impede active species transport and sulfur accommodation.
• Addressing polysulfide shuttle and improving energy density remain key challenges.

Purpose of the Study:

• To develop solid porous carbon spheres (PNCS) as an advanced sulfur host for Li-S batteries.
• To improve ion/electron transport pathways and cathode/electrolyte contact area.
• To enhance polysulfide conversion kinetics and overall battery performance.

Main Methods:

• Synthesis of solid porous carbon spheres (PNCS) with high porosity and surface area.
• Integration of PNCS with nitrogen-doped graphene (NG) to form a composite cathode material.
• Electrochemical characterization of Li-S batteries using the PNCS/NG cathode, including cycling tests, rate capability, and performance under high sulfur loading.

Main Results:

• PNCS/NG cathodes enable high sulfur loading and excellent cathode/electrolyte contact.
• Li-S batteries exhibit high initial discharge capacity (1445 mAh g^-1 at 0.2 C) and rate capability (872 mAh g^-1 at 4 C).
• Exceptional cycling stability with low capacity decay (0.047% per cycle over 500 cycles) and strong performance under practical conditions (5.5 mg cm^-2 sulfur loading, 5 μL mg^-1 E/S ratio).

Conclusions:

• Solid porous carbon spheres are effective sulfur hosts for Li-S batteries.
• The PNCS/NG composite significantly mitigates polysulfide shuttle and enhances electrochemical performance.
• This approach offers a promising strategy for developing high-performance and practical Li-S batteries.