Data-Driven Discovery of MOF-Polymer Synergies Enabling High-Performance Solid-State Sodium Batteries.

Abstract

Solid-state batteries (SSBs) are widely regarded as a promising next-generation energy storage technology owing to their intrinsic safety and high energy density. Solid polymer electrolytes (SPEs) have been esteemed as a cost-effective route to realize commercial SSBs, however, it's hindered by the low ionic conductivity at room temperature. Here, we present a data-driven strategy to screen a broad library of M-MOF-74 structures and identify Zn-MOF-74 as an optimal filler for poly(vinylidene difluoride)-based electrolytes after comprehensive structure-conductivity correlation analysis and performance prediction. The SPE-Zn-MOF electrolyte achieves an ionic conductivity of 1.02 × 10^-3 S cm^-1 at room temperature and a high Na⁺ transference number (t_Na+) of 0.84. Various structural characterizations reveal that Zn-MOF-74 suppresses the formation of PVDF microcrystallinity and anomalously inhibits the re-crystallinity of polymer during cycling, which also promotes anion dissociation through Lewis-acidic metal sites and the formation of NaF-rich interphase. These synergies extend the electrochemical stability window up to 5.1 V and support prolonged cycling stability beyond 4000 h in Na||Na cells. When integrated with layered oxide or Na₃V₂(PO₄)₃ cathodes, the optimized SPE enables both full cells achieving superior cycling stability and excellent rate capability at room temperature.