Metal Organic Frameworks Enabled Multifunctional Poly(ethylene oxide)-Based Solid Polymer Electrolytes with High Lithium-Ion Conductivity and Excellent Stability

Solid polymer electrolytes (SPEs) have the characteristics of easy processability, high flexibility, safety, and reliability. In this article, Fe-MIL-88B metal organic frameworks (Fe-MOFs) were used as fillers to modify poly(ethylene oxide) (PEO)-based SPEs, and the elemental composition, structural morphology, electrochemical stability, thermal stability, and mechanical properties of prepared samples were comprehensively characterized. Fe-MOFs can reduce the crystallization ratio of the PEO substrate and improve the mechanical properties of the solid electrolyte, effectively inhibit the protrusion of lithium dendrite, and regulate the rapid transport of Li+. The ionic conductivity of the composite electrolyte was as high as 2.3 × 10–5 S cm–1 at 30 °C and 1.05 × 10–2 S cm–1 at 80 °C, and the wide electrochemical window was about 4.8 V. The assembled Li/Li metal batteries can be recycled for 1400 h without short circuiting at the current density of 0.1 mA cm–2. At the same time, the prepared LiFePO4/Li batteries exhibited dramatic rate performance and cycle stability for over 80 cycles. The results show the application potential of the composite electrolyte in solid-state batteries (SSBs).