Thickness‐Dependence of 2D g‐C3N4 Artificial Interface Layers on Lithium Metal Deposition

Abstract

AbstractConstructing artificial interfacial layers using 2D materials with tunable physicochemical properties is a promising strategy to fabricate high‐performance lithium (Li) metal anodes. However, their structural evolution during solid‐electrolyte interphase (SEI) formation and the thickness effects on charge transport remain elusive. Herein, 2D g‐C3N4 layers with varied thicknesses are developed on the surface of copper foil to evaluate the thickness effects of artificial SEI on Li metal deposition. It is demonstrated that a thin g‐C3N4 layer (≈2 nm) is rapidly decomposed and fractured under the impact of Li‐ion flux, while a thick g‐C3N4 layer (≈50 nm) impedes the transport of lithium ions and electrons simultaneously, hindering the Li metal deposition underneath. Notably, a g‐C3N4 layer with moderate thickness (≈10 nm) dominates in‐situ generation of stable g‐C3N4/Li3N hybrid artificial SEI and enables fast Li‐ion transport, which induces uniform Li deposition. The lithium electrode protected by the moderate‐thickness g‐C3N4 layer exhibits outstanding cycling stability with a high average Coulombic efficiency of ≈98.92% for over 380 cycles and enables stable cycling of full cell with 50% Li excess and lean electrolyte. This proof‐of‐concept study provides essential guidance for the application of 2D materials in constructing artificial SEI for Li metal anodes.