Orbital Coupling of PbO 7 Node in Single-Crystal Metal-Organic Framework Enhances Li-O 2 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-O 2 ) batteries. Herein, we report the synthesis of a class of PbO 7 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 PbO 6 node in the single-crystal tetramethoxy-lead-MOF (4OMe-Pb-MOF), the bond length between Pb and O in the PbO 7 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 LiO 2 to Li 2 O 2 and the oxidation of LiO 2 to O 2 for reducing the activation energy of the overall reaction. Consequently, Li-O 2 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.