Potassium-Ion Conducting Amorphous-Based Chlorides KTaCl6 Prepared via Mechanochemistry

All-solid-state potassium batteries have attracted considerable attention as energy storage devices. The development of suitable ionic conductors has received significant attention for the commercialization of the batteries. Here, we report the potassium-ion conductors KTaCl6 prepared using the mechanochemical method and then heat treatment. The mechanochemically prepared sample comprises the monoclinic crystalline phase embedded within the amorphous component, as revealed by X-ray diffraction and transmission electron microscopy. The mechanochemically prepared sample exhibits an ionic conductivity of 1.8 × 10−5 S cm−1 at 30 °C. Upon heat treatment, the sample undergoes crystallization, leading to a decrease in ionic conductivity. It is suggested that the amorphous phase plays a key role in the ion conduction of the KTaCl6 chlorides.