<i>In Situ</i> PrO _<i>x</i> Framework Enables Reversible Reaction Pathways in Li–O ₂ Batteries

The practical reversibility of Li-O₂ batteries is constrained by the electronically insulating discharge product Li₂O₂, which limits interfacial reaction kinetics, induces large charge polarization, and accelerates electrolyte decomposition. Here we introduce Pr(NO₃)₃ as an electrolyte additive to generate in situ an amorphous, three-dimensional PrO_<i>x</i> framework on a Co₃O₄/CNT cathode during the first discharge. This framework confines Li₂O₂ growth to produce nanosized, poorly ordered Li₂O₂ and, at the same time, provides abundant active sites and continuous electron pathways for O₂ redox and Li₂O₂ formation/decomposition. As a result, the voltage gap decreases from 1.66 to 1.16 V at 200 μA cm^-2 under a limited capacity of 400 μAh cm^-2. The lowered charging potential also suppresses Li₂CO₃ formation, leading to an improved cycling stability.