Interfacial Modulation of Lithium Deposition via an Adaptive Poly(Ether‐Thiourea) Protective Layer

ABSTRACT Lithium metal is a promising anode material for high‐energy‐density batteries; however, its practical applications are significantly hindered by unstable lithium deposition and dendrite growth at the solid electrolyte interface. Functional protective coatings on lithium metal surfaces offer a viable solution to these challenges. Herein, an innovative adaptive protective layer for lithium metal anodes based on a thiourea H‐bonded supramolecular polymer is developed for the first time. With dense thiourea H‐bonding, the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) incorporated poly(ether‐thiourea) protective layer shows strong adhesion to the lithium metal surface and good adaptive properties. The unique viscoelastic and flow characteristics of the poly(ether‐thiourea) coating facilitate uniform Li⁺ flux, effectively suppressing dendrite formation at the solid electrolyte interface. Furthermore, this innovative polymer integrates in situ generated compounds, such as Li₃N and Li₂O, significantly enhancing interfacial stability. A comprehensive analysis involving X‐ray photoelectron spectroscopy, scanning electron microscopy, X‐ray tomography, and COMSOL simulations elucidates the beneficial effects of the adaptive coating. Enhanced performances in Li||Cu, Li ||Li, Li||LiFePO 4 , and Li||S cells demonstrate the effectiveness of the poly(ether‐thiourea) coating and its undeniable capability to improve lithium deposition and cycling stability. This study highlights a promising new candidate for developing supramolecular materials capable of stabilizing lithium metal anodes.