Bifunctional N, S Dual-Doped Carbon Enabling Fast Polysulfide Redox and Stable Lithium Deposition

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries offer high theoretical capacity but face challenges with poor cycling stability and rate performance.
• Sluggish redox kinetics during Li2S2 to Li2S conversion and unstable lithium deposition hinder Li-S battery efficiency and safety.
• Existing Li-S battery designs struggle with uneven ion distribution and dendrite formation, compromising long-term viability.

Purpose of the Study:

• To design and investigate a novel interlayer for enhancing sulfur redox electrochemistry in Li-S batteries.
• To address issues of sluggish kinetics and unstable lithium deposition through a functional interlayer.
• To improve the overall electrochemical performance and safety of Li-S batteries.

Main Methods:

• Fabrication of a nitrogen and sulfur dual-doped carbon (NSC) interlayer.
• Electrochemical characterization of Li-S cells incorporating the NSC interlayer.
• Analysis of lithium deposition behavior and polysulfide conversion kinetics.

Main Results:

• The NSC interlayer significantly boosts electrochemical performance, achieving 1215 mAh g⁻¹ at 0.2C and 617 mAh g⁻¹ at 5C.
• Active sites (N…Li and SB⁰) within the NSC interlayer accelerate polysulfide conversion and regulate lithium deposition.
• The NSC interlayer facilitated uniform lithium deposition for over 1000 hours, enhancing battery stability.

Conclusions:

• The developed NSC interlayer effectively reinforces sulfur redox electrochemistry and promotes uniform Li deposition in Li-S batteries.
• This functional interlayer strategy offers a facile method for advancing Li-S battery technology towards high energy efficiency.
• The study opens new avenues for designing advanced interlayers to overcome critical limitations in next-generation batteries.