In Situ Plasma Polymerization of Self‐Stabilized Polythiophene Enables Dendrite‐Free Lithium Metal Anodes with Ultra‐Long Cycle Life

Abstract Constructing a flexible and chemically stable multifunctional layer for the lithium (Li) metal anodes is a highly effective approach to improve the uneven deposition of Li + and suppress the dendrite growth. Herein, an organic protecting layer of polythiophene is in situ polymerized on the Li metal via plasma polymerization. Compared with the chemically polymerized thiophene (C‐PTh), the plasma polymerized thiophene layer (P‐PTh), with a higher Young's modulus of 8.1 GPa, shows strong structural stability due to the chemical binding of the polythiophene and Li. Moreover, the nucleophilic C─S bond of polythiophene facilitates the decomposition of Li salts in the electrolytes, promoting the formation of LiF‐rich solid electrolyte interface (SEI) layers. The synergetic effect of the rigid LiF as well as the flexible PTh‐Li can effectively regulate the uniform Li deposition and suppress the growth of Li dendrites during the repeated stripping‐plating, enabling the Li anodes with long‐cycling lifespan over 8000 h (1 mA cm −2 , 1 mAh cm −2) and 2500 h (10 mA cm −2 , 10 mAh cm −2 ). Since the plasma polymerization is facile (5–20 min) and environmentally friendly (solvent‐free), this work offers a novel and promising strategy for the construction of the forthcoming generation of high‐energy‐density batteries.