Lithium Bis(fluorosulfonyl)imide for Stabilized Interphases on Conjugated Dicarboxylate Electrode

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Carbonyl-based negative electrodes, like lithium terephthalate (LiTPA), offer high energy density and sustainability for rechargeable lithium batteries.
• Poor solid-electrolyte-interphase (SEI) layer quality currently limits the cell performance of LiTPA electrodes.
• Developing stable SEI layers is crucial for advancing lithium battery technology.

Purpose of the Study:

• To investigate the use of lithium bis(fluorosulfonyl)imide (LiFSI) as an electrolyte salt for LiTPA negative electrodes.
• To improve the cyclability and rate performance of LiTPA-based lithium batteries by forming a superior SEI layer.
• To understand the electrochemical reduction processes of FSI- anions on negative electrodes.

Main Methods:

• Electrochemical testing of LiTPA electrodes using LiFSI-based electrolytes.
• Comparison with reference electrolytes containing lithium hexafluorophosphate (LiPF6).
• Analysis of the SEI layer composition and properties.

Main Results:

• Electrochemical reduction of FSI- anions occurred before LiTPA lithiation, forming an inorganic-rich SEI layer.
• The SEI layer contained lithium fluoride (LiF) and lithium sulfate (Li2SO4).
• LiFSI-based cells demonstrated significantly improved cycling performance compared to LiPF6-based cells.

Conclusions:

• LiFSI is effective in forming a Li-ion permeable SEI layer on LiTPA electrodes.
• The use of LiFSI enhances the cyclability and rate performance of LiTPA-based lithium batteries.
• This research provides insights into FSI- anion reduction, promoting sustainable and high-energy battery development.