The Impact of Solvent Exposure During Preparation on the Performance of Poly(ethylene) Oxide-Li1.5Al0.5Ge1.5(PO4)3 Hybrid Electrolytes

Abstract

Hybrid electrolytes are comprised of a salt-containing polymer and an ion-conducting ceramic. The general appeal of these electrolytes is that they combine the desirable properties of each component. Namely, the flexibility, processibility and interface compatibility of the polymer and the mechanical strength and high ionic conductivity of the ceramic. In this work, hybrid electrolytes comprised of poly(ethylene oxide) (PEO) and Li1.5Al0.5Ge1.5(PO4)3 (LAGP) were prepared using two different methods: solvent casting in acetonitrile and melt processing using a micro compounder. The presence of added solvents has been shown to impact the properties and stability of polymer electrolytes, but the effect of residual solvents on hybrid electrolytes has not been extensively investigated. Hybrid electrolytes prepared by solvent-free melt processing were compared to those prepared by solution casting, with and without vacuum drying, to determine the impact of solvent exposure on the properties of the electrolyte. Preparation via melt processing improved the dispersion of the ceramic phase in the polymer matrix which resulted in lower tortuosity and higher ionic conductivity. The absence of acetonitrile and low water content in the melt-processed sample improved stability during long-term cycling in Li-Li symmetric cells.