In Situ PrOx Framework Enables Reversible Reaction Pathways in Li-O2 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 PrOx 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.