Orbital Coupling of PbO₇ Node in Single-Crystal Metal-Organic Framework Enhances Li-O₂ Battery Electrocatalysis

Optimizing the local coordination environment of metal centers in metal-organic frameworks (MOFs) is crucial yet challenging for regulating the overpotential of lithium-oxygen (Li-O₂) batteries. Herein, we report the synthesis of a class of PbO₇ nodes in a single crystal MOF (naphthalene-lead-MOF, known as Na-Pb-MOF) to significantly enhance the kinetics of both discharge and charge processes. Compared to the PbO₆ node in the single-crystal tetramethoxy-lead-MOF (4OMe-Pb-MOF), the bond length between Pb and O in the PbO₇ node of Na-Pb-MOF increases, resulting in weaker Pb 5d-O 2p orbital coupling, which optimizes the adsorption interaction toward intermediates, and thereby promotes the rate-determining steps of both the reduction of LiO₂ to Li₂O₂ and the oxidation of LiO₂ to O₂ for reducing the activation energy of the overall reaction. Consequently, Li-O₂ batteries based on Na-Pb-MOF electrocatalysts exhibit a low total charge-discharge overpotential of 0.52 V and an excellent cycle life of 140 cycles.