Imidazole-Based Lithium Salt LiHDI as a Solid Electrolyte Interphase-Stabilising Additive for Lithium-Conducting...

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Solid electrolyte interphase (SEI) formation is critical for lithium-ion battery longevity.
• Conventional additives like fluoroethylene carbonate (FEC) and vinylene carbonate (VC) have limitations.
• Developing novel SEI-stabilizing additives is crucial for advancing battery performance.

Purpose of the Study:

• To investigate the efficacy of lithium 4,5-dicyano-2-(n-heptafluoropropyl)imidazolide (LiHDI) as an SEI-stabilizing additive in lithium-ion batteries.
• To compare the performance of LiHDI with conventional additives (FEC, VC) and additive-free electrolytes.
• To evaluate the impact of LiHDI on electrolyte properties, electrochemical performance, and SEI composition.

Main Methods:

• Electrochemical testing including galvanostatic cycling at room temperature and 60 °C.
• Measurement of electrolyte conductivity and internal cell resistance.
• X-ray photoelectron spectroscopy (XPS) analysis of electrode surfaces after cycling.

Main Results:

• LiHDI demonstrates comparable chemical and thermal stability to LiTDI.
• LiHDI does not negatively impact electrolyte properties.
• LiHDI significantly improves capacity retention in graphite-LiFePO4 cells, outperforming FEC-VC mixtures, especially at elevated temperatures.
• Internal cell resistance correlates with improved capacity retention.
• XPS analysis reveals LiHDI influences SEI composition.

Conclusions:

• LiHDI is a highly effective SEI-stabilizing additive for lithium-ion batteries.
• LiHDI offers superior performance, particularly at elevated temperatures, compared to FEC-VC.
• LiHDI presents a promising avenue for enhancing battery cycle life and stability.