Simultaneous Solvation Structure Modulation and In Situ Gelation Enables Robust Anode Interface for Ambient Lithium‐Air Batteries

Lithium‐air batteries (LABs) are highly esteemed for their perfect energy density. However, the high reactivity of lithium (Li) metal anode with the electrolyte, air crossover, and shuttled redox mediators severely confines the practical performance of LABs. Herein, a hybrid SEI layer (denoted as H‐SEI) with the feature of flexible‐exterior and rigid‐interior is spontaneously grown on Li metal surface using highly concentrated Li salt gel solution, in which anions modifies the Li + solvation structure and accordingly induces a dense and rigid inorganic‐rich inner SEI layer, in the meantime, Li salt initiates the in situ polymerization of gel monomers to form a flexible gel polymer outer SEI layer. Thanks to the powerful capability of the inorganic inner layer in rapid Li + transport and strong dendrite suppression, and that of the gel outer layer in excellent interfacial adaptability, the Li||Li symmetric cell with H‐SEI‐modified Li metal electrodes (termed H‐SEI@Li) achieves exceptional reversibility in terms of a high critical current density (CCD) of 10 mA cm −2 and long‐term cycling over 900 h. On this basis, the LAB based on H‐SEI@Li delivers a large discharge capacity of 9525.83 mAh g −1 , and an ultra‐long cycle life for 755 cycles in air, significantly outperforming the counterpart using bare Li as an anode.