Mechanochemical Synthesis of Fluorine-Doped NaTaCl6 Electrolytes

Abstract Sodium-ion-conducting chlorides, particularly NaTaCl6, have attracted attention for their high ionic conductivity and oxidation stability. Here, NaTaCl6−xFx (x = 0–6) was synthesized by mechanochemical treatment to improve electrochemical stability. F doping decreased ionic conductivity, whereas NaTaCl5.75F0.25 exhibited an electrochemical potential window of 1.5–4.1 V vs. Na+/Na and stable cycling for 50 cycles at 60 °C in an all-solid-state cell. These results suggest that F doping effectively tunes the electrochemical stability of NaTaCl6-based solid electrolytes.