Free-Standing Selenium Impregnated Carbonized Leaf Cathodes for High-Performance Sodium-Selenium Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-selenium batteries are promising for next-generation energy storage due to selenium's high theoretical capacity.
• Developing stable and efficient cathodes remains a key challenge for practical sodium-selenium battery applications.

Purpose of the Study:

• To develop a novel carbon-selenium composite cathode using a sustainable leaf-based carbon material.
• To investigate the electrochemical performance of this composite as a binder- and current collector-free electrode for sodium-selenium batteries.

Main Methods:

• Carbonization of leaves via thermal pyrolysis with melt diffusion.
• Selenium vapor deposition onto the carbonized leaf structure.
• Fabrication of binder- and current collector-free composite cathodes.
• Electrochemical testing including cycling stability and rate capability assessment.

Main Results:

• The leaf-derived carbonized material exhibits hierarchical porosity and high mass loading.
• The composite cathode achieved a high reversible specific capacity of 520 mA h g^-1 at 100 mA g^-1 after 120 cycles.
• Exceptional cycling stability was observed with 300 mA h g^-1 at 2 A g^-1 after 500 cycles without capacity loss.
• The unique 3D structure of the leaf-based carbon facilitates ion and electron transport, enhancing selenium utilization.

Conclusions:

• A novel, high-performance carbon-selenium composite cathode was successfully fabricated using readily available leaves.
• The binder- and current collector-free design and unique porous structure contribute to excellent electrochemical performance.
• This approach presents a promising strategy for developing advanced electrodes for efficient sodium-selenium batteries.