Formulating Electrolytes for 4.6 V Anode-Free Lithium Metal Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• High-voltage anode-free lithium metal batteries (AFLMBs) offer high energy density but suffer from poor reversibility of the cathode and lithium metal anode.
• Ensuring long cycle life requires addressing the stability issues of both battery components.

Purpose of the Study:

• To formulate a novel concentrated electrolyte for high-voltage AFLMBs.
• To enhance the stability and reversibility of the lithium metal anode and high-voltage cathode.
• To improve the overall cycle life and performance of AFLMBs.

Main Methods:

• Formulation of a concentrated electrolyte with dual salts (LiTFSI and LiDFOB) in mixed solvents (DMC and FEC) and a LiNO3 additive.
• Investigation of the electrolyte's effect on the solid electrolyte interphase (SEI) formation on the lithium metal anode.
• Evaluation of the electrolyte's performance with a Li-rich high-voltage cathode (Li1.2Mn0.54Ni0.13Co0.13O2).

Main Results:

• The formulated electrolyte enabled a high lithium plating/stripping Coulombic efficiency of 98.3% due to a LiF, Li3N-rich SEI.
• LiDFOB additive suppressed side reactions at the high-voltage cathode.
• The battery demonstrated stable operation for 80 cycles at 4.6 V, with initial irreversible capacity contributing to cycle life extension.

Conclusions:

• The developed electrolyte effectively enhances the stability of both the cathode and anode in high-voltage AFLMBs.
• This formulation strategy provides insights for creating advanced electrolytes for next-generation lithium metal batteries.
• The study paves the way for the practical application of high-energy-density AFLMBs.