In-situ metallic cobalt layer for multifunctional synergistic effects in high-performance Lithium metal batteries

Lithium metal batteries suffer from unstable interphases due to uncontrolled dendrite growth and continuous electrolyte depletion. Research indicates that constructing a solid electrolyte interphase (Hereinafter referred to as SEI) film enriched with lithium fluoride (LiF) can effectively suppress lithium dendrite growth and reduce the occurrence of side reactions. However, existing research has primarily focused on the formation mechanism of LiF and its concentration within the SEI, while neglecting a critical parameter in the film formation kinetics—the LiF formation rate. This limitation has resulted in a lack of effective strategies for rapidly forming high-performance SEIs rich in LiF. This work introduces a cobalt-based organometallic salt additive, wherein the exchange reaction between cobalt and lithium ions in situ generates a catalytic metallic cobalt layer. Through active sites on the cobalt layer surface, TFSI − anions are strongly adsorbed and catalyzed to decompose at the interphase. This layer synergistically optimizes the electrolyte to promote LiF formation. This strategy effectively accelerates TFSI − decomposition, hastens Li + desolvation, reduces nucleation overpotential, and guides uniform lithium deposition/stripping, thereby significantly suppressing dendrite propagation. Consequently, the Li||Cu half-cell achieves a Coulombic efficiency of up to 99.77% under the Aurbach test; while the Li||LFP full cell retained 72.37% capacity after 400 cycles under stringent conditions (N/ P  = 1.1, 1 C). This site-specific catalytic strategy provides an effective pathway for constructing stable inorganic-rich SEI layers, paving a promising road toward developing safe and durable lithium metal batteries.