Sonochemical synthesis and characterization of SnF2 as a potential fluoride-ion conducting solid electrolyte

Abstract

Fluoride ion batteries (FIBs) are emerging as a promising alternative to conventional lithium-ion batteries, primarily because of their high theoretical energy density and environmentally sustainable characteristics. For the development of a high-performance solid-state fluoride ion battery, an engineered electrolyte is crucial. As the synthesis technique impacts the phase, microstructure, and morphology of the materials, a unique and facile sonochemical route is employed for the first time herein for synthesizing Tin (II) fluoride as a solid electrolyte. The XRD investigations have indicated the formation of the α-SnF2 phase with a monoclinic structure, and space group C2/c. The particle size of SnF2 synthesized using 225 W and 325 W power of probe sonicator is found to be 2 μm and 0.8 μm respectively, as revealed by Scanning Electron Micrographs. SnF2 prepared with 325 W ultrasonic power has exhibited the maximum ionic conductivity of value 3.4 × 10−4 S/cm at room temperature, with a significant enhancement regarding the values reported so far. The anionic transport number of the electrolyte estimated at room temperature using the combined AC-DC technique is found to be 0.96, indicating fluoride ion conduction.