MOF-Derived Hierarchically Porous Carbon with Orthogonal Channels for Advanced Na-Se Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-selenium (Na-Se) batteries are promising due to selenium's high theoretical capacity and abundance.
• Key challenges include selenium's significant volume expansion and the polyselenide shuttling effect, which degrade battery performance.

Purpose of the Study:

• To develop a novel electrode material for high-performance Na-Se batteries.
• To address the limitations of volume expansion and polyselenide shuttling in Na-Se battery systems.

Main Methods:

• Hierarchically porous carbon encapsulated selenium (Se/HPC) was synthesized by infiltrating molten selenium into an indium-metal-organic framework (In-MOF) derived carbon matrix.
• Electrochemical performance was evaluated through cycling tests and capacity retention measurements.
• Density functional theory (DFT) calculations were employed to investigate sodium-ion adsorption and diffusion mechanisms.

Main Results:

• The Se/HPC electrode demonstrated effective nano-confinement of selenium, buffering volume expansion and suppressing polyselenide shuttling.
• High specific capacity of 465 mAh g^-1 at 50 A g^-1 was achieved.
• Exceptional long-term cycling stability was observed, with 533 mAh g^-1 after 2800 cycles at 10 A g^-1 and a decay rate of only 0.003% per cycle.
• DFT calculations confirmed the beneficial role of Se─C bonds in facilitating Na⁺ adsorption and diffusion.

Conclusions:

• The developed Se/HPC electrode significantly enhances the electrochemical performance of Na-Se batteries.
• The in-situ construction of a hierarchically porous carbon matrix derived from MOFs is an effective strategy for high-performance selenium-based energy storage.
• This approach provides valuable insights for designing advanced electrode materials for next-generation sodium batteries.