Boosting the ionic conductivity of amorphous oxychloride solid electrolytes via different degrees of amorphization

Solid electrolytes provide improved safety, greater electrochemical and thermal stability, and better compatibility with high-energy materials than liquid electrolytes. Compared to crystalline solid electrolytes, amorphous solid electrolytes offer reduced grain boundary resistance, enhanced processability, isotropic ionic conductivity and superior mechanical properties. Herein, the impacts of varying high-energy ball milling intensities on the degree of amorphization of amorphous 1.6Li₂O-TaCl₅ oxychloride and thus its ionic conductivity are investigated. It is shown that the ionic conductivity of amorphous 1.6Li₂O-TaCl₅ can reach as high as 8.30 x 10^-3 S/cm at room temperature by increasing the degree of amorphization. Furthermore, the sample exhibiting the highest ionic conductivity also releases the largest stored enthalpy upon heating, indicating that structural defects in amorphous 1.6L_i2O-TaCl₅ materials play a crucial role in enhancing their Li-ion conductivities. This discovery opens the door for boosting the ionic conductivities of other amorphous electrolytes in the future via increasing the degree of amorphization.