Artificial LiF-Rich Interface Enabled by In situ Electrochemical Fluorination for Stable Lithium-Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-metal batteries offer high energy density but suffer from unstable solid electrolyte interfaces (SEI) due to electrolyte degradation.
• Fragile and nonuniform SEI layers lead to dendrite growth and poor battery cyclability.

Purpose of the Study:

• To develop a hybrid anode using fluorinated carbon nanotube macrofilm (CMF) for lithium-metal batteries.
• To investigate the ability of the fluorinated CNT-CMF to regulate the anode/electrolyte interface and form a stable SEI.
• To enhance the electrochemical performance and long-term stability of lithium-metal batteries.

Main Methods:

• A fluorinated carbon nanotube macrofilm (CMF) was employed as a hybrid anode on lithium metal.
• The fluorination process was studied during the charging cycle to form a LiF-rich SEI.
• Electrochemical performance, including cyclability and rate capacity, was evaluated in full cells.

Main Results:

• The fluorinated CNT-CMF facilitated the direct formation of a LiF-rich SEI with a high Young's modulus (~2.0 GPa) and fast ionic conductivity (~2.59×10^-7 S cm^-1).
• The engineered SEI guided homogeneous lithium plating/stripping and effectively suppressed dendrite growth.
• Full cells utilizing the hybrid anode demonstrated significantly enhanced cyclability with ~99.3% capacity retention and remarkable rate capability.

Conclusions:

• The fluorinated CNT-CMF hybrid anode effectively stabilizes the solid electrolyte interface in lithium-metal batteries.
• This fluorination strategy provides a platform for controlling artificial SEI formation, improving battery stability and longevity.
• The developed technology holds promise for advancing next-generation high-performance energy storage systems.