In situ ZIF-67-functionalized polypropylene separator for stabilized Mg deposition and quinone shuttle inhibition in Mg-organic batteries

Magnesium-metal organic batteries (MMOBs) combine high charge-storage capacity with resource abundance and favorable material economics. However, their application is limited by dissolved organic shuttle and separator issues, including thick, costly glass fiber (GF) separators and poor coating adhesion on commercial separators. Herein, we report a rationally designed ZIF-67@polypropylene (PP) separator, fabricated via a robust in situ nucleation strategy that yields a dense, binder-free, and conformal MOF layer on both faces of a commercial substrate. Compared with conventional coating, this in situ modification strategy not only suppresses shuttle and improves wettability, but also strengthens interfacial bonding, enhancing mechanical robustness and durability. Benefiting from well-defined pores, ZIF-67 acts as an ion sieve that effectively suppresses anthraquinone (AQ) dissolution/shuttle while facilitating Mg 2+ transport and accelerating redox kinetics. Consequently, symmetric Mg||Mg cells employing this modified separator deliver an extended lifespan exceeding 1300 h with a mere ∼90 mV overpotential at 0.05 mA cm −2 . More impressively, Mg||AQ full cells demonstrate exceptional durability, retaining a reversible capacity of 94.5 mAh g −1 after 250 cycles at 0.1 A g −1 . This work highlights the critical role of in-situ separator modification in unlocking the full potential of sustainable MMOBs.