High Performance Li Metal Anode Enabled by Robust Covalent Triazine Framework-Based Protective Layer

Advanced high-energy-density energy storage systems with high safety are desperately demanded to power electric vehicles and smart grids. Li metal batteries (LMBs) can provide a considerable leap in battery energy. Nevertheless, the widespread deployment of Li metal has long been fettered by the unstable solid electrolyte interlayer and uncontrolled Li dendrite growth induced safety concerns. Herein, a flexible and conformal CTF-LiI coating has been rationally coated on Li metal surface to stabilize metallic Li. With the CTF-LiI coating, the Li electrodeposition exhibits a uniform, dense, and dendrite-free manner; however, the side reactions between metallic Li and electrolyte have been effectively suppressed. The Li symmetric cells can run stably for a prolonged cycling over 2500 cycles at 10 mA cm⁻², demonstrating a much lower voltage hysteresis. In addition, the Li|Li₄Ti₅O₁₂ cells can deliver an improved long-time cycling over 250 cycles at 0.05 A g⁻¹. Furthermore, the half cells paired with the organic S cathode also demonstrate an excellent long lifespan stable cycling and a high capacity of 682.2 mAh g⁻¹ retained over 300 cycles with an average capacity decay of ≈0.05% per cycle at 1.0 A g⁻¹. This work demonstrates a significant step toward large-scalable and long-cycling stable LMBs.