Core-Shell Tandem Catalysis Coupled with Interface Engineering For High-Performance Room-Temperature Na-S Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Room-temperature sodium-sulfur (RT Na-S) batteries face challenges from sluggish redox kinetics and the shuttle effect, limiting their practical application.
• A single catalyst is insufficient to address the complex, multi-step sulfur redox process.

Purpose of the Study:

• To design and fabricate a cathode material with dual catalysts to overcome the limitations of RT Na-S batteries.
• To improve the catalytic efficiency of the entire sulfur redox conversion process.

Main Methods:

• Fabrication of a nitrogen-doped core-shell carbon nanosphere integrated with ZnS nanocrystals (core) and isolated Ni-N4 sites (shell).
• Investigating the synergistic catalytic effects of ZnS and Ni-N4 on sulfur reduction and polysulfide conversion.
• Characterization of the cathode-electrolyte interface (CEI) and electrochemical performance.

Main Results:

• The ZnS core efficiently reduces S8 to Na2Sx, while the Ni-N4 shell catalyzes Na2Sx conversion to Na2S.
• The Ni-N4 sites promote an inorganic-rich CEI, effectively inhibiting the shuttle effect.
• The ZnS-NC@Ni-N4/S cathode achieved excellent rate performance (650 mAh g-1 at 5 A g-1) and ultralong cycling stability (2000 cycles with 0.011% decay per cycle).

Conclusions:

• The developed dual-catalyst cathode material significantly enhances the electrochemical performance of RT Na-S batteries.
• This work provides a rational design strategy for multicatalyst systems for high-performance sodium-sulfur batteries.