Aprotic Lithium–Oxygen Batteries Based on Nonsolid Discharge Products

Aprotic lithium-oxygen (Li-O₂) batteries are considered to be a promising alternative option to lithium-ion batteries for high gravimetric energy storage devices. However, the sluggish electrochemical kinetics, the passivation, and the structural damage to the cathode caused by the solid discharge products have greatly hindered the practical application of Li-O₂ batteries. Herein, the nonsolid-state discharge products of the off-stoichiometric Li_1-xO₂ in the electrolyte solutions are achieved by iridium (Ir) single-atom-based porous organic polymers (termed as Ir/AP-POP) as a homogeneous, soluble electrocatalyst for Li-O₂ batteries. In particular, the numerous atomic active sites act as the main nucleation sites of O₂-related discharge reactions, which are favorable to interacting with O₂^-/LiO₂ intermediates in the electrolyte solutions, owing to the highly similar lattice-matching effect between the in situ-formed Ir₃Li and LiO₂, achieving a nonsolid LiO₂ as the final discharge product in the electrolyte solutions for Li-O₂ batteries. Consequently, the Li-O₂ battery with a soluble Ir/AP-POP electrocatalyst exhibits an ultrahigh discharge capacity of 12.8 mAh, an ultralow overpotential of 0.03 V, and a long cyclic life of 700 h with the carbon cloth cathode. The manipulation of nonsolid discharge products in aprotic Li-O₂ batteries breaks the traditional growth mode of Li₂O₂, bringing Li-O₂ batteries closer to being a viable technology.