Defect-Engineered MOF-Regulated Solvation and Interfacial Stability in Composite Polymer Electrolytes for Dendrite-Free Lithium-Metal Batteries

Composite solid polymer electrolytes (CSPEs) have attracted considerable attention for lithium-metal batteries (LMBs); nevertheless, their practical implementation remains constrained by slow ion-transport pathways, filler–polymer phase separation, uncontrolled solvent decomposition, and unstable solid–electrolyte interphases (SEIs). Herein, we report a defect-rich amine-functionalized metal–organic framework (D-MOF) as a multifunctional regulator to engineer solvation chemistry, interfacial stability, and ion-transport pathways in a CSPE. The D-MOF with abundant Lewis acidic metal sites, −NH2 functional groups, and high surface area effectively disrupts Li–DMF solvation structures, immobilizes TFSI– anions, and traps residual solvent molecules, thereby suppressing DMF-induced interfacial degradation. As a result, the CSPE/D-MOF-10 membrane forms a stable and thin SEI, significantly reduces charge-transfer resistance, and enables homogeneous lithium plating/stripping. Our optimized electrolyte exhibits a high critical current density of 1.0 mA cm–2, a low nucleation overpotential of 31 mV, and ultralong symmetric cell cycling exceeding 690 h. Full cells assembled with LiFePO4 cathodes deliver excellent rate capability and long-term cycling stability, retaining 95.85% capacity retention over 454 cycles at 0.5C. In situ calorimetric analysis further reveals substantially suppressed irreversible heat generation, confirming mitigated side reactions and enhanced interfacial robustness. This work demonstrates a defect-engineering strategy applied on MOFs to regulate solvent chemistry and interfacial dynamics, providing a viable pathway toward safe, high-rate, and durable LMBs.