Synergistic Electrocatalysis and Spatial Nanoconfinement to Accelerate Sulfur Conversion Kinetics in Aqueous Zn-S...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous zinc batteries offer high theoretical energy density, low cost, and safety.
• Conversion-type sulfur cathodes face challenges due to sluggish reaction kinetics, leading to lower discharge voltage and inefficient sulfur utilization.
• These limitations suppress the practical energy density of zinc-sulfur batteries.

Purpose of the Study:

• To develop a high-performance cathode material for aqueous zinc batteries.
• To address the kinetic limitations of sulfur cathodes by enhancing sulfur reduction reaction (SRR) kinetics.
• To improve the overall energy density and efficiency of zinc-sulfur batteries.

Main Methods:

• Fabrication of sulfur nanoparticles confined within sulfur and nitrogen co-doped carbon nanofibers (S@S,N-CNF) with a yolk-shell S@C nanostructure.
• Utilized successive sulfidation, pyrolysis, and sulfide oxidation processes for material synthesis.
• Employed density functional theory (DFT) calculations to investigate reaction mechanisms and energy barriers.

Main Results:

• The S@S,N-CNF composite exhibits a yolk-shell S@C nanostructure, enhancing charge transfer and lowering activation energy.
• Sulfur and nitrogen co-doping effectively catalyzes the sulfur reduction reaction (SRR) by reducing energy barriers and accelerating kinetics.
• DFT calculations confirmed that dual-doping significantly reduces the energy barrier of the rate-determining step in SRR, boosting kinetics.

Conclusions:

• The developed S@S,N-CNF cathode material demonstrates significantly improved SRR kinetics and performance in aqueous zinc batteries.
• The synergistic effects of the yolk-shell structure and S,N-co-doping are crucial for enhancing electrochemical performance.
• This work provides a promising strategy for designing advanced cathode materials for high-performance aqueous zinc-sulfur batteries.