Plasticized perfluorinated membrane with ethylene carbonate–sulfolane mixture as polyelectrolyte with unipolar sodium conductivity for sodium-ion batteries
摘要
The development and study of novel solid polymer electrolytes for metal-ion batteries represents a critical component in the contemporary energy landscape, as they are pivotal in the creation of safer and more adaptable devices, along with a broader operational temperature range. This work undertakes a thorough investigation into the sodium form of a commercial analog of the widely known Nafion™ perfluorinated sulfonic cation-exchange membrane, plasticized with a blend of ethylene carbonate and sulfolane. The analysis of ionic conductivity, molecular structure, thermal properties, and morphology of the samples was conducted. The results of NMR and IR spectroscopy showed that the molecular structure of the studied polymer membrane coincides with that of Nafion. Thermal decomposition of the polymers is observed at temperatures above 450 °C. The sample, which was plasticized with a mixture of equimass content of the solvents, was found to demonstrate the most favorable characteristics. The single-ionic conductivity values of this sample decrease by only two orders of magnitude from 1.3 × 10–3 to 2.4 × 10–5 S cm–1 when the temperature is reduced from 70 to –50 °C. No phase transitions are observed within the aforementioned temperature range. This electrolyte is electrochemical stability up to 4.5 V vs. Na+/Na0. The efficiency of the obtained electrolyte in a full cell of a sodium-ion battery has been demonstrated.