Anion-Rich Interface via a Self-Assembled Monolayer toward a Long-Lifespan Li Metal Battery

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium metal batteries offer high energy density but suffer from unstable solid electrolyte interphase (SEI) and lithium dendrite growth.
• These interfacial issues limit the practical application and long-term cycling performance of lithium metal batteries.

Purpose of the Study:

• To develop a novel strategy for stabilizing the SEI and homogenizing lithium deposition in lithium metal batteries.
• To mitigate lithium dendrite growth and improve the overall cycling performance.

Main Methods:

• Introducing positively charged self-assembled monolayers (SAMs) onto ceramic-coated separators.
• Creating an anion-rich interface near the lithium metal anode through electrostatic attraction.
• Analyzing the preferential decomposition of salt anions and the formation of stable inorganic components (e.g., LiF).
• Evaluating the impact of immobilized anions on lithium-ion transference number and dendrite mitigation.

Main Results:

• The anion-rich interface promotes the formation of a stable, anion-derived SEI, notably LiF.
• Positively charged SAMs immobilize anions, improving the Li+ transference number to approximately 0.73.
• Significant mitigation of dendritic lithium growth was observed.
• Enhanced long-term cycling performance of lithium metal batteries was achieved.

Conclusions:

• Self-assembled monolayers on ceramic-coated separators provide an effective method to stabilize the SEI and suppress lithium dendrites.
• This approach offers a promising pathway for advancing the practical application of high-energy lithium metal batteries.