Lithium–air battery performance boosted by in situ formed Sn(II)-(TEGDME, I−)-superoxo complexes

Lithium–air batteries (LABs) offer exceptional theoretical energy density, and substantial efforts have been devoted to understanding their mechanisms and designing effective catalysts. However, LAB development is still challenged by the sluggish kinetics of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), as well as undesirable parasitic reactions associated with reduced oxygen species. Here, soluble SnI 2 is introduced into LiTFSI-TEGDME electrolyte to change the traditional LiO 2 intermediate path, forming a stable Sn(II)-(TEGDME, I − )-superoxo intermediate during the ORR process. This electrochemical intermediate induces an extended slope-shaped discharge plateau above 2.73 V vs. Li/Li + with no deposition of solid discharge products, indicating the enhanced solubility of superoxide species. The cell delivers an exceptional full discharge capacity of approximately 79000 mAh g carbon − 1 at a current density of 100 mA g carbon − 1 , accompanied by the growth of a porous solid discharge product. Furthermore, SnI 2 cooperates synergistically with the OER catalyst tris4-(diethylamino)phenylamine, prolonging the durability to over 900 cycles, with an energy efficiency higher than 90% before the 637th cycle at a current density of 500 mA g carbon − 1 and a fixed capacity of 1000 mAh g carbon − 1 . This strategy establishes a new paradigm for enabling the synergistic facilitation of both ORR and OER kinetics by regulating the electrochemical intermediate for high-performance LABs. • Quasi- operando EPR spectroscopy reveals strong superoxide-adducts signals alongside a silent singlet oxygen ( 1 O 2 ) signal. • The SnI 2 catalyst enhances the solubility of LiO 2 and Li 2 O 2 intermediates, effectively suppressing parasitic reactions. • The SnI 2 -TDPA composite empowers lithium–air batteries with an ultrahigh full discharge capacity and an ultralong cycle life.