A long life sodium-selenium cathode by encapsulating selenium into N-doped interconnected carbon aerogels

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Selenium cathodes offer high capacity and conductivity for sodium-ion batteries.
• Challenges include capacity fading due to volume changes and polyselenide shuttle effect.

Purpose of the Study:

• To develop a stable and high-performance cathode material for sodium-selenium batteries.
• To address the limitations of pure selenium cathodes.

Main Methods:

• Fabrication of selenium-carbon aerogel composites (Se@NCAs) via infiltration.
• Utilizing N-doped interconnected carbon aerogels as a host matrix.
• Electrochemical characterization of Na-Se batteries with Se@NCA cathodes.

Main Results:

• Se@NCA cathodes demonstrated high discharge capacity (600 mAh g⁻¹ after 50 cycles at 0.1 A g⁻¹).
• Superior rate capability was achieved (430 mAh g⁻¹ at 2 A g⁻¹).
• Excellent long-term cycling stability was observed (407 mAh g⁻¹ after 800 cycles at 0.5 A g⁻¹ with 0.04% capacity decline per cycle).

Conclusions:

• The carbon aerogel matrix effectively accommodates volume expansion and suppresses polyselenide shuttling.
• N-doped carbon aerogels provide a promising host for high-performance selenium cathodes in sodium-selenium batteries.