Realizing the dendrite-free sulfide-based all-solid-state Li metal battery by surface design

Although the ultrahigh ionic conductivity of sulfide-type solid electrolytes is comparable to that of liquid electrolytes, the low critical current density (CCD) limits the practical application of solid-state lithium (Li) metal batteries. The insufficient Li0 self-diffusion in solid Li leads to the voids that form at the interface at a large stripping current density, which results in interface contact loss and the increase of local current density. Herein, an artificial hybrid interphase layer dominated by Li3Sb and LiF was constructed on the Li surface to explore the Li plating/stripping behavior at the Li/Li6PS5Cl interface. The Li3Sb alloy provides a fast Li0 diffusion channel to avoid the interfacial voids formation and current focusing, while the electrically insulated LiF acts an electron blocking shield at the Li/Li6PS5Cl interface. Consequently, the symmetric cells reveal a significantly increased CCD of 1.8 mA cm−2 and a stable Li plating/stripping for 1472 h with a high current density of 2 mA cm−2 at 50°C. Moreover, the all-solid-state Li-SPAN cell with Li3Sb/LiF interphase exhibits good capacity retention of 83.2% after 120 cycles at 0.5 C, and it also delivers a superior rate performance of 400 mAh g−1 at 5C. The construction of lithium-alloy interphase is a promising alternative to solid-state lithium battery applications.