Co₂C/CoC₈ heterostructure towards polysulfide capture/conversion for advanced lithium-sulfur batteries

Yiyang Li ¹, Yuexuan He ¹, Bo Jin ²

⁰Key Laboratory of Automobile Materials, Ministry of Education, and College of Materials Science and Engineering, Jilin University, Changchun 130022, China.

Journal of Colloid and Interface Science +

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June 14, 2025

View abstract on PubMed

Summary

This study introduces a novel nanostructured material (Co2C/CoC8/NEC) to boost lithium-sulfur battery performance by enhancing lithium polysulfide trapping and conversion. This material significantly improves capacity retention and cycling stability, paving the way for advanced battery technologies.

Area Of Science

Materials Science
Electrochemistry
Energy Storage

Background

Lithium-sulfur batteries (LSBs) face challenges from slow redox kinetics and lithium polysulfide (LiPS) shuttle effects, limiting their practical application.
Developing advanced electrode materials and separators is crucial to overcome these limitations and enhance LSB performance.

Purpose Of The Study

To design and synthesize a nanostructured material (Co2C/CoC8/NEC) combining cobalt carbides and nitrogen-doped carbon for improved LiPS management in LSBs.
To investigate the synergistic effects of Co2C, CoC8, and nitrogen doping on LiPS adsorption and catalytic conversion.
To evaluate the electrochemical performance of LSBs utilizing the developed material in electrodes and separators.

Main Methods

Hydrothermal synthesis followed by heat treatment to prepare the Co2C/CoC8/NEC nanostructured material.
Fabrication of LSBs with Co2C/CoC8/NEC integrated into the cathode and separator.
Electrochemical testing including cycling performance, rate capability, and long-term stability assessments.
Density functional theory (DFT) calculations to elucidate the roles of Co2C and CoC8 in the reaction mechanisms.

Main Results

The Co2C/CoC8/NEC material demonstrated enhanced LiPS trapping and catalytic conversion due to the synergistic action of Co2C, CoC8, and nitrogen doping.
LSBs utilizing Co2C/CoC8/NEC achieved a high initial discharge capacity of 1131 mAh g⁻¹ at 0.5 C, with 977 mAh g⁻¹ retained after 300 cycles (86% retention).
Exceptional long-term cycling stability was observed, with a capacity decay rate of only 0.023% per cycle over 1500 cycles at 1 C.
The battery maintained good electrochemical performance under demanding conditions, including high sulfur loading (5.6 mg cm⁻²) and lean electrolyte (E/S ratio of 4.5 μL mg⁻¹).

Conclusions

The developed Co2C/CoC8/NEC nanostructured material effectively addresses the challenges of LiPSs in LSBs, significantly enhancing battery performance and durability.
This work highlights the potential of transition metal carbides (TMCs) in designing high-performance LSBs and suggests broader applicability in other secondary battery systems.

Keywords:

Catalysis and capturing Cobalt carbide Density functional theory calculation Electrocatalyst Long-term cycling stability

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Sulfides are the sulfur analog of ethers, just as thiols are the sulfur analog of alcohol. Like ethers, sulfides also consist of two hydrocarbon groups bonded to the central sulfur atom. Depending upon the type of groups present, sulfides can be symmetrical or asymmetrical. Symmetrical sulfides can be prepared via an SN2 reaction between 2 equivalents of an alkyl halide and one equivalent of sodium sulfide.

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