Exquisite hybridized electrocatalyst with moderate selenium element integration for reliable lithium-sulfur batteries

Area of Science:

• Materials Science and Engineering
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries offer high theoretical energy density but suffer from poor cycle life due to lithium polysulfide (LiPS) shuttling.
• Effective immobilization and catalytic conversion of LiPSs are critical for improving Li-S battery performance.

Purpose of the Study:

• To design and evaluate a hybrid CoSe2-Co3O4-Se@CNTs electrocatalyst for enhanced LiPS management in Li-S batteries.
• To elucidate the role of selenium in the catalytic process and its contribution to battery stability.

Main Methods:

• Fabrication of a hybrid CoSe2-Co3O4-Se@CNTs electrocatalyst.
• Modification of a separator with the synthesized electrocatalyst.
• In situ X-ray diffraction (XRD) to study reaction mechanisms.
• Electrochemical performance testing of Li-S cells (discharge capacity, capacity retention, cycling stability).

Main Results:

• The CoSe2-Co3O4-Se@CNTs electrocatalyst demonstrated synergistic effects in adsorbing and catalyzing LiPSs.
• In situ XRD revealed the active participation of selenium in charge-discharge reactions.
• Li-S cells with the modified separator exhibited high initial discharge capacity (1,412 mAh g⁻¹ at 0.1 C) and excellent capacity retention (71% after 400 cycles).
• Exceptional cycling stability was observed at higher rates (0.5 C and 1 C) with very low decay rates (0.053% per cycle).

Conclusions:

• The hybrid CoSe2-Co3O4-Se@CNTs electrocatalyst effectively immobilizes and catalyzes LiPSs, significantly improving Li-S battery performance.
• Selenium plays an active and crucial role in the electrochemical reactions, contributing to enhanced cycling stability.
• This study presents a promising strategy for developing advanced electrocatalysts to extend the operational lifespan of Li-S batteries.