Solid electrolyte manufacturing methods and its effect on SSB performance

• Solid polymer electrolytes are dependent on the manufacturing method. • Extrusion method with ceramic fillers and a thickness of 70 um improves the cell cyclability. • It avoids the growth of dendrites and the blocking type polarization of the SPE. The impact of the manufacturing method on the final properties of the Solid Polymer Electrolyte (SPE) has been studied for polymer complexes made by poly(ethylene oxide) (PEO) with dissolved lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. Various SPEs processed by solvent casting or extrusion have been manufactured consisting of a mixture of two polymer molecular weights (4,000,000 g mol - 1 and 300,000 g/mol) with and without ceramic fillers, and various membrane thicknesses ranging from 70 to 200 μm. The study explores the changes in morphology, crystallization behaviour, rheological, and thermal properties of the obtained SPEs and their correlation with the electrochemical performance and the degradation mechanism of the final pouch cell. The use of the extrusion method to introduce passive ceramic fillers in the SPE combined with a final thickness of 70 µm has shown a significant improvement demonstrating the strong influence of the manufacturing method to extend the cell cyclability. Specifically, the SPE mechanical properties together with a thickness reduction are key factors for avoiding the growth of dendrites and the blocking type polarization of the SPE that are the main causes of the degradation mechanism observed in this study. This comprehensive analysis contributes to an optimal SPE fabrication for scalable and efficient production of SSBs in the evolving field of energy storage.