Enhanced Na+ Transport in Cu-MOF Reinforced PEO Solid-State Polymer Electrolyte for High-Rate Sodium Metal Batteries

Poly(ethylene oxide) (PEO)-based solid polymer electrolytes are regarded as highly promising solid electrolyte materials owing to their favorable chain flexibility. However, their practical application is hindered by low room-temperature ionic conductivity and poor mechanical properties. To address these issues, a metal–organic framework (Cu-MOF) with a 2D layered structure and 1D microchannels is introduced into PEO to form a composite solid electrolyte. The results reveal that Cu-MOF can suppress PEO crystallization through steric hindrance and coordination interactions, thereby increasing the fraction of the amorphous phase. Moreover, its unsaturated metal sites can attract TFSI−anions, promoting the dissociation of the sodium salt and enhancing sodium-ion transport. Theoretical calculations and molecular simulations further confirm the regulatory role of Cu-MOF in ion transport. Leveraging this mechanism, the Na3V2(PO4)3/C|PCM-8%|Na cell delivers exceptional electrochemical performance over a wide temperature range. At room temperature, the capacity exhibits virtually no decay after 200 cycles at 0.5 C, and outstanding rate capability is maintained even at a high rate of 4 C. At a temperature of 65 °C, a capacity retention of 91.4% is achieved after 200 cycles at 0.5 C. This study offers a highly promising strategy for the development of wide-temperature-range, high-performance solid-state sodium batteries.