A Composite Electrolyte Based on Li1.6Al0.6Ge1.4(PO4)3 and Polyvinylidene Fluoride

Abstract

Abstract We propose an approach to fabricating a “polymer-in-ceramic” composite electrolyte based on polyvinylidene fluoride (PVDF) and lithium aluminum germanium phosphate with a NASICON structure of the composition Li1.6Al0.6Ge1.4(PO4)3 (LAGP06), which features a higher aluminum content compared to the commercially produced Li1.5Al0.5Ge1.5(PO4)3. The optimal polymer content in the composite (20 wt %) was determined, which enables the formation of a thin film (LAGP06–PVDF) with a relatively high ionic conductivity of up to 1.3 × 10–3 S/cm. The area-specific resistance of electrolyte in a Li|LAGP06–PVDF|Li cell was 15 Ω cm2. The lithium-ion transference number of the composite electrolyte was found to be 0.62. The LAGP06–PVDF electrolyte is electrochemically stable up to 4.85 V. The symmetric Li|LAGP06–PVDF|Li cells are characterized by good compatibility an overpotential of ≤40 mV at a current density of ±0.1 mA/cm2 and exhibit stable operation for ~1000 plating/stripping cycles.