In situ constructed LiAg/LiF hybrid interphase to enable lithiophilic nucleation and electron blocking for dendrite-free lithium metal anodes

Lithium metal anodes (LMAs) are regarded as a promising candidate for next generation high-energy-density batteries. However, their practical application is severely limited by unstable solid electrolyte interphases (SEI), uncontrolled dendrite growth, and pronounced interfacial side reactions. Herein, an artificial hybrid interfacial layer composed of LiAg alloy and LiF is constructed on the lithium surface through an in situ reaction with silver trifluoromethanesulfonate (AgOTF). This strategy enables the functional integration of rapid Li⁺ transport and robust electronic shielding, thereby effectively mitigating the aforementioned challenges. In symmetric cells, the modified anode delivers a high critical current density (CCD) of 22.5 mA cm⁻² and sustains stable cycling for over 1400 h at a current density of 1 mA cm⁻². When coupled with commercial LiFePO₄ cathodes, the full cell exhibits excellent cycling stability, retaining 84% of its initial capacity after 400 cycles at 1.0C. Theoretical calculations further indicate that LiAg features enhanced Li adsorption capability and a reduced diffusion barrier, which facilitate lower nucleation overpotential and faster Li⁺ migration. Meanwhile, LiF effectively suppresses electron leakage and parasitic side reactions owing to its high electronic insulation, thereby enabling synergistic ionic transport and electronic shielding. Furthermore, the AgOTF@Li anode exhibits markedly improved stability under ambient air conditions compared with pristine lithium foil. This facile and efficient strategy provides a viable pathway toward the practical realization of high-performance lithium metal batteries.