Optimized Co–S bonds energy and confinement effect of hollow MXene@CoS2/NC for enhanced sodium storage kinetics and stability

Qun Li, Qingze Jiao, Yu Yan, Huanjun Li, Wei Zhou*, Tingting Gu, Xueran Shen, Chengxing Lu, Yun Zhao, Yaoyuan Zhang, Hansheng Li, Caihong Feng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

74 Citations (Scopus)

Abstract

The sluggish kinetics and severe volume expansion are two major drawbacks that limiting the application of transition metal sulfides electrode materials for sodium ion batteries (SIBs). Herein, we assembled Ti3C2Tx MXene nanosheets into thin-walled hollow spheres with PMMA spheres as sacrificial template, on which MOF-derived CoS2 nanoparticles embedded in N-doped carbon were grown (MXene@CoS2/NC). The MXene@CoS2/NC exhibits state-of-the-art sodium ion storage properties, including a high reversible capacity of 620 mAh g−1 at 0.2 A g−1, superior rate capability (394 mAh g−1 at 5 A g−1), and excellent cycling stability (355 mAh g−1 after 5000 cycles). The corresponding electrochemical tests prove that the MXene@CoS2/NC has fast Na+ ion diffusion and electron transfer compared with its counterpart without MXene interfaces. XPS and XANES characterizations disclose the introduced MXene and increased pyrrolic N can weaken the Co-S bonds of CoS2, which facilitates the conversion reaction between CoS2 and Na2S, and thus improves the sodium storage kinetics. The DFT calculations also demonstrate the MXene can improve the conductivity of electrode materials by fast interfacial electron transfer. In addition, the MXene hollow spheres and MOF-derived NC provide host structures for CoS2, which can increase the contact between electrolyte and active materials, buffer the volume expansion of CoS2, and thus enhancing the electrochemical stability. This work provides a feasible strategy to construct anode materials for SIBs with improved sodium storage kinetics and cycling stability.

Original languageEnglish
Article number137922
JournalChemical Engineering Journal
Volume450
DOIs
Publication statusPublished - 15 Dec 2022

Keywords

  • Co–S bonds energy
  • Electrochemical stability
  • Hetero-interfaces
  • MXene
  • Sodium ion battery

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Li, Q., Jiao, Q., Yan, Y., Li, H., Zhou, W., Gu, T., Shen, X., Lu, C., Zhao, Y., Zhang, Y., Li, H., & Feng, C. (2022). Optimized Co–S bonds energy and confinement effect of hollow MXene@CoS2/NC for enhanced sodium storage kinetics and stability. Chemical Engineering Journal, 450, Article 137922. https://doi.org/10.1016/j.cej.2022.137922