Conductivity Optimization of Tysonite-type La1–xBaxF3–x Solid Electrolytes for Advanced Fluoride Ion Battery

Use of lithium ion batteries is currently the method of choice when it comes to local stationary storage of electrical energy. In the search for an alternative system, fluoride ion batteries (FIBs) emerge as a candidate due to their high theoretical capacity, and no lithium is needed for its operation. To improve the cycling performance and lower the working temperature of a solid-state battery, one of the critical components is the electrolyte, which needs advanced performance. This paper aims at developing an electrolyte with enhanced ionic conductivity for fluoride ions, to be used in a FIB. Tysonite La1–xBaxF3–x (0 ≤ x ≤ 0.15) solid solutions were synthesized by a facile wet chemical method, and its ionic conductivity was analyzed using electrochemical impedance spectroscopy. A composition study shows that the conductivity reaches a maximum of 1.26 × 10–4 S·cm–1 at 60 °C for the La0.95Ba0.05F2.95 pellet sintered at 800 °C for 20 h, which is 1 order of magnitude higher than that for the as-prepared pel...