Protecting Lithium Metal Electrode With Titanium Based Interphase: Synthesis and Battery Performance

Atomic layer deposition (ALD) of interphases is a promising strategy for stabilizing lithium metal negative electrode and mitigating dendrite formation in rechargeable batteries. In this work, we investigate the growth mechanism and electrochemical impact of titanium-based ALD coatings on highly reactive lithium surfaces. Operando ambient-pressure X-ray photoelectron spectroscopy (APXPS) was employed to probe the initial stages of a Ti interphase growth under realistic ALD conditions using TiCl₄ and H₂O precursors. The first H₂O pulse rapidly converts the Li surface into LiOH, while subsequent TiCl₄ exposure reacts directly with lithium surface to form a stable LiCl interlayer. TiO_x nucleates on this LiCl-modified surface, resulting in a composite TiO_x/LiCl interphase. This synergistic interphase improves electrolyte wettability, promotes uniform Li⁺ flux, and suppresses dendritic growth. Electrochemical evaluation shows that TiO_x-LiCl-coated Li anodes deliver substantially enhanced interfacial stability and cycling performance. Symmetric cells exhibit stable operation for over 600 h, while full Li‖LiNi_0.8Mn_0.1Co_0.1O₂ cells with a 10 ALD cycle TiO_x/LiCl coating achieve 100% Coulombic efficiency after 300 charge–discharge cycles at 200 mA g⁻¹, compared with ∼63% for bare lithium. These findings provide mechanistic insight and practical validation of ALD Ti-based coatings as an effective protection strategy for durable lithium metal batteries.