Sodium-Selenium Batteries with Outstanding Rate Capability by Introducing Cubic Mn₂ O₃ Electrocatalyst

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-selenium (Na-Se) batteries offer high volumetric capacity and conductivity.
• Irreversible sodium selenide deposition causes capacity fade and low Coulombic efficiency in Na-Se batteries.

Purpose of the Study:

• To introduce cubic α-Mn₂O₃ as an electrocatalyst to improve Na-Se battery performance.
• To enhance the utilization of active materials and mitigate capacity degradation.

Main Methods:

• Incorporation of cubic α-Mn₂O₃ as an electrocatalyst in selenium/Ketjen black (Se/KB) composites.
• Analysis of Na₂Se conversion kinetics and sodium-ion transport.

Main Results:

• 10 wt% Mn₂O₃ addition lowered the activation energy for Na₂Se conversion to Se.
• Enhanced sodium-ion kinetics and reduced internal resistance were observed.
• The Mn₂O₃-based composite achieved a specific capacity of 635 mAh·g⁻¹ at 675 mA·g⁻¹ after 250 cycles.
• Excellent cycling stability was demonstrated with 317 mAh·g⁻¹ at 3375 mA·g⁻¹ after 800 cycles.

Conclusions:

• Cubic α-Mn₂O₃ effectively catalyzes Na₂Se conversion, improving Na-Se battery performance.
• The developed composite exhibits superior electrochemical performance compared to state-of-the-art Na-Se batteries.