A ZIF-8/carbon-modified commercial PEP separator enabling stable magnesium deposition and effective quinone shuttle suppression in magnesium–organic batteries

Magnesium-metal organic batteries (MMOBs) are promising candidates for large-scale energy storage due to their high theoretical capacity, abundant resource, and cost-effectiveness. However, the high solubility of organic molecules and the commonly used thick glass fiber separators with poor mechanical strength and high cost hinder their further development. Herein, we report a ZIF-8/Carbon composite-modified polypropylene/polyethylene/polypropylene (ZIF-8/C@PEP) separator to overcome these limitations. This ZIF-8/C@PEP separator was fabricated by uniformly coating a mixture of ZIF-8 and carbon black onto a PEP separator via a doctor-blade method. The porous structure of ZIF-8 acts as a molecular sieve, effectively blocking the diffusion of soluble anthraquinone (AQ) species toward the anode while allowing facile Mg 2+ ion transport. Meanwhile, the carbon black enhances the separator’s compactness and provides additional physical confinement and adsorption sites for soluble molecules. Benefiting from these synergistic effects, by implementing the ZIF-8/C@PEP separator, Mg||Mg cells exhibit stabilized Mg plating/stripping behavior with reduced overpotential, while Mg||AQ full cells deliver good cyclability, maintaining a capacity of 104.8 mAh g −1 after 100 cycles at 0.05 A g −1 with a Coulombic efficiency of 98%. The results demonstrate that separator modification represents a promising strategy for enhancing the performance of MMOBs.