Graphene-Selenium Hybrid Microballs as Cathode Materials for High-performance Lithium-Selenium Secondary Battery...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-selenium (Li-Se) batteries are promising next-generation energy storage devices.
• Developing efficient cathode materials is crucial for improving Li-Se battery performance.
• Selenium's low conductivity and polyselenide dissolution limit its practical application.

Purpose of the Study:

• To prepare graphene-selenium hybrid microballs (G-SeHMs) using a scalable aerosol microdroplet drying method.
• To investigate the potential of G-SeHMs as cathode material for lithium-selenium secondary batteries.
• To analyze the electrochemical properties and performance-enhancing mechanisms of G-SeHMs.

Main Methods:

• One-step synthesis of G-SeHMs via aerosol microdroplet drying using a commercial spray dryer.
• Electrochemical characterization, including specific capacity, cycling stability, and rate capability testing.
• Structural analysis to understand the role of graphene in confining selenium and facilitating electron transport.

Main Results:

• G-SeHMs exhibited high initial specific capacity (642 mAh g⁻¹ at 0.1 C) with 95.1% Se utilization.
• Excellent cycling stability was achieved (544 mAh g⁻¹ after 100 cycles at 0.1 C, 84.5% retention).
• High rate capability was demonstrated (301 mAh g⁻¹ at 5 C), surpassing previously reported Se-based cathodes.

Conclusions:

• The G-SeHM structure effectively confines polyselenides and provides an electron conduction pathway.
• High selenium loading (80 wt%) contributes to the superior electrochemical performance.
• The facile, scalable synthesis method makes G-SeHMs a promising cathode material for advanced lithium-selenium batteries.