Li-ion dynamics and relaxation in wet-chemical synthesized argyrodite-type Li7−4xAlxP1−xS6−3x solid electrolyte

Herein, Li7−4xAlxP1−xS6−3x (x = 0, 0.1, 0.2 and 0.3) solid electrolytes were prepared via liquid-phase synthesis. X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive spectroscopy were employed to characterise the structure of the prepared samples. XRD data refinement confirmed that Al was successfully incorporated into the crystal structure of the low-temperature (LT) phase of argyrodite-type Li7PS6. At 25 °C, the ionic conductivities for x = 0, 0.1, 0.2 and 0.3 were 2.3 × 10−5, 1.2 × 10−4, 7.4 × 10−5 and 3.2 × 10−5 S·cm−1, respectively. The ionic conductivity of LT-Li7PS6 prepared in this study was enhanced by Al doping and reached 1.2 × 10−4 S·cm−1 in the sample with x = 0.1. The data from alternating-current electrochemical impedance spectroscopy were analysed to find that the thermally active mechanism of mobile Li+ migration was the primary contributor to ionic conduction of the prepared samples.