Rationally designing S/Ti₃C₂T_x as a cathode material with an interlayer for high-rate and long-cycle lithium-sulfur...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries offer high theoretical energy density but face challenges like poor cycling stability and low conductivity.
• Dissolution of lithium polysulfides and low intrinsic conductivity of sulfur are key limitations hindering practical applications.

Purpose of the Study:

• To develop an effective host material for sulfur cathodes to overcome Li-S battery limitations.
• To enhance the rate performance and cycling stability of sulfur cathodes through composite design and interlayer integration.

Main Methods:

• Synthesis of Ti3C2Tx "clay" by selective aluminum layer extraction from Ti3AlC2 using HCl and LiF.
• Preparation of a single-walled carbon nanotube thin film interlayer via vacuum filtration.
• Fabrication and electrochemical testing of sulfur cathodes utilizing the Ti3C2Tx host and carbon nanotube interlayer.

Main Results:

• The S/Ti3C2Tx composite cathode with a carbon nanotube interlayer exhibited a high initial discharge capacity of 1458 mA h g-1 at 0.1 A g-1.
• Exceptional cycling stability was achieved with an ultralow capacity decay of 0.04% per cycle at 0.8 A g-1 for over 1500 cycles.
• Superior rate capability was demonstrated, with a reversible capacity of 608 mA h g-1 at a high current density of 8.2 A g-1 (≈5C).

Conclusions:

• Ti3C2Tx "clay" serves as a promising host material for sulfur cathodes in Li-S batteries.
• The integration of a single-walled carbon nanotube interlayer significantly boosts rate performance and long-term cycling stability.
• This approach offers a viable strategy for developing high-rate, long-cycle life Li-S batteries.