Elucidating the suppression of lithium dendrite growth with a void-reduced anti-perovskite solid-state electrolyte pellet for stable lithium metal anodes

Solid-state lithium-metal batteries, with their high theoretical energy density and safety, are highly promising as a next-generation battery contender. Among the alternatives proposed as solid-state electrolyte, lithium-rich anti-perovskite (LiRAP) materials have drawn the most interest because of high theoretical Li+ conductivity, low cost and easy processing. Although solid-state electrolytes are believed to have the potential to physically inhibit the lithium dendrite growth, lithium-metal batteries still suffer from the lithium dendrite growth and thereafter the short circuiting. The voids in practical LiRAP pellets are considered as the root cause. Herein, we show that reducing the voids can effectively suppress the lithium dendrite growth. The voids in the pellet resulted in an irregular Li+ flux distribution and a poor interfacial contact with lithium metal anode; and hence the ununiform lithium dendrites. Consequently, the lithium-metal symmetric cell with void-reduced Li2OHCl-HT pellet was able to display excellent cycling performance (750 h at 0.4 mA cm−2) and stability at high current density (0.8 mA cm−2 for 120 h). This study provides not only experimental evidence for the impact of the voids in LiRAP pellets on the lithium dendrite growth, but also a rational pellet fabrication approach to suppress the lithium dendrite growth.