Lithium zinc/lithium iodide composite modified layer toward highly stable lithium metal anodes

•A LiZn alloy/LiI hybrid protective layer in introduced on the surface of Li metal anode.•The hybrid protective layer reduces the nucleation barrier and facilitates Li+ diffusion.•The hybrid protective layer improves the electrochemical properties of Li metal anode. Lithium metal batteries (LMBs) are considered by most researchers as among the most prospective next-generation high energy density storage devices because of high theoretical capacity (3860 mAh g − 1) and low reduction potential (–3.040 V compared to standard hydrogen electrode) of Li metal anode. Nevertheless, the uncontrollable dendrite growth of the Li metal anode during cycling hinders the commercial application of LMBs. Herein, we put forward a hybrid protective layer containing LiZn alloy and LiI at the surface of the Li metal anode. Thanks to the "lithiophilic" feature of LiZn alloy and LiI having a low surface Li+ diffusion energy barrier, the constructed homogeneous hybrid protective layer can reduce the nucleation barrier and facilitate Li+ rapid diffusion. As a consequence, Li metal anode exhibits a smooth plating/stripping morphology and can suppress the dendrite formation. Notably, the constructed ZI@Li || ZI@Li symmetrical cell realizes stable cycling for 470 h at 2 mA cm−2 and 2 mAh cm−2, and LMBs matched with commercial LiFePO4 cathode deliver greatly enhanced electrochemical properties. This hybrid protective layer provides a feasible strategy to realize even plating/stripping of Li metal, which would promote the high energy density LMBs for practical applications. [Display omitted]