Recent progress in constructing fluorinated solid-electrolyte interphases for stable lithium metal anodes

Lithium metal batteries (LMBs) are emerging as a promising energy storage solution owing to their high energy density and specific capacity. However, the non-uniform plating of lithium and the potential rupture of the solid-electrolyte interphase (SEI) during extended cycling use may result in dendrite growth, which can penetrate the separator and pose significant short-circuit risks. Forming a stable SEI is essential for the long-term operation of the batteries. Fluorine-rich SEI has garnered significant attention for its ability to effectively passivate electrodes, regulate lithium deposition, and inhibit electrolyte corrosion. Understanding the structural components and preparation methods of existing fluorinated SEI is crucial for optimizing lithium metal anode performance. This paper reviews the research on optimizing LiF passivation interfaces to protect lithium metal anodes. It focuses on four types of compositions in fluorinated SEI that work synergistically to enhance SEI performance. For instance, combining compounds with LiF can further enhance the mechanical strength and ionic conductivity of the SEI. Integrating metals with LiF significantly improves electrochemical performance at the SEI/anode interface, with a necessary focus on reducing electron tunneling risks. Additionally, incorporating polymers with LiF offers balanced improvements in interfacial toughness and ionic conductivity, though maintaining structural stability over long cycles remains a critical area for future research. Although alloys combined with LiF increase surface energy and lithium affinity, challenges such as dendrite growth and volume expansion persist. In summary, this paper emphasizes the crucial role of interfacial structures in LMBs and offers comprehensive guidance for future design and development efforts in battery technology.