Robust Transport: An Artificial Solid Electrolyte Interphase Design for Anode-Free Lithium-Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Anode-free lithium-metal batteries (AFLMBs) offer high energy density but suffer from capacity fade due to solid electrolyte interphase (SEI) mechanical degradation.
• Existing artificial SEI materials face a trade-off between ionic conductivity and mechanical robustness, limiting their effectiveness.

Purpose of the Study:

• To develop a composite artificial SEI with enhanced mechanical toughness and high ionic conductivity for AFLMBs.
• To overcome the limitations of current SEI materials in maintaining structural integrity and performance.

Main Methods:

• A co-sputtering approach was used to create a composite artificial SEI integrating lithium fluoride (LiF) and lithium phosphorus oxynitride (LiPON).
• The structural and electrochemical properties of the LiF-LiPON heterostructure were analyzed.

Main Results:

• The integrated LiF-LiPON SEI exhibited significantly improved fracture toughness (by an order of magnitude) due to the high Young's modulus of LiF domains.
• The heterostructure facilitated additional Li+ transport pathways, achieving ionic conductivity >10^-6 S cm^-1.
• AFLMBs utilizing this artificial SEI demonstrated a cycling lifetime increase of over 250%.

Conclusions:

• The developed tenacious composite artificial SEI effectively addresses SEI mechanical degradation in AFLMBs.
• Integrating materials with contrasting properties (LiF and LiPON) is a viable strategy for designing high-performance SEI layers.
• Fracture toughness is a critical factor for the long-term structural integrity and performance of AFLMBs.