Molecularly Programmed MOF Electrodes Enable Spatial Regulation of Triple-Phase Boundaries in Li-O2 Batteries

초록

Li-O-2 batteries are limited by spatially heterogeneous triple-phase boundary (TPB) reactions caused by opposing Li+ and O-2 transport, leading to localized Li2O2 nucleation, pore blockage, and restricted capacity. Here, we demonstrate nanoscale transport programming of a hierarchical metal-organic framework (MIL-121) to decouple and regulate ionic and gaseous flux. Thermal activation generates anhydride sites for orthogonal functionalization with Li+-coordinating groups (PMIL-121@Li) and O-2-binding Fe-porphyrin motifs (PMIL-121@Heme). These functionalities independently enhance Li+ conduction and local O-2 availability, rebalancing reactant supply at the TPB. When assembled into a spatially encoded multilayer architecture, the functionalized MOF layers directionally modulate reactant transport across electrode depth, converting localized TPBs into a uniformly extended reaction interface. This enables homogeneous Li2O2 deposition, delivering 4.3 mAh cm(-2) at 0.1 mA cm(-2) with stable cycling over 45 cycles. This work establishes molecularly engineered MOFs as a platform for regulating multiphase transport and stabilizing TPB dynamics in Li-O-2 systems.

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