Binary Atomic Sites Enable a Confined Bidirectional Tandem Electrocatalytic Sulfur Conversion for Low-Temperature...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Current all-solid-state sodium-sulfur (Na-S) batteries face challenges with high operating temperatures and poor sulfur utilization.
• Sluggish polysulfide redox kinetics and uncontrolled sulfur speciation limit the theoretical potential of Na-S battery chemistry.

Purpose of the Study:

• To develop a low-temperature all-solid-state Na-S battery with enhanced performance.
• To address limitations of sulfur utilization and polysulfide kinetics through a novel catalytic approach.

Main Methods:

• Fabrication of a bifunctional hollow sulfur matrix with atomically dispersed MnN4 and CoN4 hotspots using a sacrificial template process.
• Utilization of a Na3Zr2Si2PO12 ceramic membrane as a platform for confined bidirectional tandem electrocatalysis.
• Investigation of the catalytic effect on polysulfide electrochemistry during battery cycling.

Main Results:

• The bifunctional catalyst effectively tuned polysulfide electrochemistry, enabling low-temperature (80°C) operation.
• CoN4 sites catalyzed polysulfide reduction, while MnN4 sites accelerated Na2S4 to Na2S conversion, ensuring uniform Na2S deposition.
• The synergistic effect of the catalysts mitigated cathodic passivation and improved Na2S decomposition during recharging.

Conclusions:

• The developed all-solid-state Na-S battery demonstrates stable cycling with a reversible capacity of 1060 mAh g⁻¹, high Coulombic efficiency (98.5%), and high energy density (1008 Wh kgcathode⁻¹).
• This approach offers a promising pathway for high-performance, low-temperature solid-state sodium-sulfur batteries, comparable to liquid electrolyte systems.