Reticular Assembly of Complex Cage-within-Cage Merged-Net MOFs for Lithium-Ion Conductivity

Anionic metal-organic frameworks (MOFs) with charge-balancing cations and tunable pore structures are considered promising solid-state electrolytes toward high energy-density lithium metal batteries (LMBs). However, MOF-based electrolytes suffer from inherent decomposition, due to poor electrochemical stability and low intrinsic ionic conductivity at low temperatures. Here, we reported reticular assembly of an anionic zinc-azolate MOF─Zn-TBTB─featuring cage-within-cage structures with complex (3,6,6)-connected pco net, a merged net of 6-connected pcu-b and (3,4)-connected bor net. The merged-net structural nature endows Zn-TBTB high electrochemical stability and modular mixed-anionic pore environments, resulting in a high voltage window and low-temperature Li⁺ conduction. The single-ion conduction mechanism was further supported by impedance spectroscopy and solid-state nuclear magnetic resonance experiments. The quasi-solid-state lithium metal battery can stably operate across a wide temperature range. This work provides a molecular foundation for designing MOF-based electrolytes with good low-temperature performances, advancing the development of reliable LMBs under wide-range operational conditions.