Electrochemical performance of the mixed solid electrolyte (100-x)Li3SI-xLi6PS5Cl (x = 0, 10, 20, and 30) for all-solid-state lithium batteries

In this study, solid electrolytes with improved performance are synthesized by mixing Li3SI with an anti-perovskite structure that is stable to lithium metal and Li6PS5Cl with high ionic conductivity. (100–x)Li3SI-xLi6PS5Cl (x = 0, 10, 20, 30), which is a mixture of two sulfide-based solid electrolytes, is prepared by ball milling. The structural characteristics, surface morphology, and particle size of the electrolyte material are analyzed using physico-chemical characterization technologies, such as high-power X-ray diffraction and field emission scanning electron microscopy. Electrochemical impedance spectroscopy is used to calculate the ionic conductivity of the mixed solid electrolyte. The ionic conductivity of 80Li3SI–20Li6PS5Cl, which exhibits the best all-solid-state lithium battery performance, is 5.84 × 10−4 S cm−1. In addition, 80Li3SI–20Li6PS5Cl shows excellent stability against lithium metal. The 2032-type coin cell composed of fabricated Li–In/80Li3SI–20Li6PS5Cl/NCM811 composites shows a superior capacity of 165 mAh g−1 in the initial cycle. This study provides high ionic conductivity and excellent electrochemical performance through the mixing of two kinds of solid electrolyte materials to obtain a promising solid electrolyte.