Fabrication of the Li6PS5Cl-LiFSI Composite for All-Solid-State Li-Ion Batteries

The ionic conductivity of an argyrodite-type solid electrolyte Li6PS5Cl can be improved by aliovalent substitution. Although the ionic conductivity of Li6PS5Cl has been intensively studied, its electrochemical stability enhancement was rarely reported. In this study, Li6PS5Cl-LiFSI composite solid electrolytes were prepared to study the effect of LiFSI addition on the stability of Li6PS5Cl in low- and high-voltage regions. The structure of the prepared solid electrolytes was characterized using XRD, Raman spectroscopy, and SEM-EDS. Rietveld refinement was further employed to confirm their structure. The component-dependent oxidation and electrochemical compatibility of the prepared solid electrolytes were studied by linear sweep voltammetry (LSV) and cyclic voltammetry (CV). The Li-Li symmetrical cell using the 80Li(6)PS(5)Cl-20LiFSI composite was stable for about 500 h when being periodically charged-discharged at +/- 0.1 similar to +/- 0.8 mA cm(-2). The capacity and stability of solid-state cells, which employed 80Li(6)PS(5)Cl-20LiFSI and 90Li(6)PS(5)Cl-10LiFSI, were superior to the one using Li6PS5Cl when being cycled at a high voltage of about 4.0-2.4 V vs Li-In, which was about 4.6-3.0 V vs Li/Li+.