Improved electrochemical performance of a LiCoO₂/MCMB cell by regulating fluorinated electrolytes

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• High-voltage lithium cobalt oxide (LCO) cathodes face capacity decay due to phase transitions and electrolyte reactions.
• Conventional carbonate electrolytes are unstable with charged LCO, limiting battery performance.

Purpose of the Study:

• To develop stable fluorinated electrolytes for high-voltage LCO cathodes.
• To investigate the impact of fluorinated solvent composition on electrolyte properties and interfacial chemistry.
• To evaluate the electrochemical performance of LCO/MCMB cells using these novel electrolytes.

Main Methods:

• Synthesis and characterization of various fluorinated electrolytes.
• Electrochemical testing of LCO/MCMB half and full cells.
• Analysis of interfacial chemistry on cathode and anode surfaces.

Main Results:

• Fluorinated electrolytes significantly improve reversible capacity and cycle life.
• Enhanced electrolyte oxidation resistivity and modified interfacial films contribute to improved stability.
• A novel perfluorinated electrolyte (fluorinated carbonate and ether) demonstrates superior performance in LCO/MCMB full cells at 4.45 V.

Conclusions:

• Fluorinated electrolytes are effective in stabilizing high-voltage LCO cathodes.
• Synergistic effects of fluorinated solvents enhance battery cycle capability and performance.
• The developed perfluorinated electrolyte offers a promising solution for advanced lithium-ion batteries.