Interface design for high-performance all-solid-state lithium batteries

All-solid-state batteries suffer from high interface resistance and lithium dendrite growth leading to low Li plating/stripping Coulombic efficiency (CE) of <90% and low critical current density at high capacity. Here, simultaneously addresses both challenges are simultaneously addressed and the Li plating/stripping CE is significantly increased to 99.6% at 0.2 mA cm${}^{-2}$/0.2 mAh cm${}^{-2}$, and critical current density (CCD) of > 3.0 mA cm${}^{-2}$/3.0 mAh cm${}^{-2}$ by inserting a mixed ionic-electronic conductive (MIEC) and lithiophobic LiF-C-Li${}_3$N-Bi nanocomposite interlayer between Li${}_6$PS${}_5$Cl electrolyte and Li anode. The highly lithiophobic LiF-C-Li${}_3$N-Bi interlayer with high ionic conductivity (10${}^{-5}$ S cm${}^{-1}$) and low electronic conductivity (3.4×10${}^{-7}$ S cm${}^{-1}$) enables Li to plate on the current collector (CC) surface rather than on Li${}_6$PS${}_5$Cl surface avoiding Li${}_6$PS${}_5$Cl electrolyte reduction. During initial Li plating on CC, Li penetrates into porous LiF-C-Li${}_3$N-Bi interlayer and lithiates Bi nanoparticles into Li${}_3$Bi. The lithiophilic Li${}_3$Bi and Li${}_3$N nanoparticles in LiF-C-Li${}_3$N-Li${}_3$Bi sub-interlayer will move to CC along with plated Li, forming LiF-C/Li${}_3$N-Li${}_3$Bi lithiophobic/lithiophilic sublayer during the following Li stripping. This interlayer enables Co${}_{0.1}$Fe${}_{0.9}$S${}_2$/Li${}_6$PS${}_5$Cl/Li cell with an areal capacity of 1.4 mAh cm${}^{-2}$ to achieve a cycle life of >850 cycles at 150 mA g${}^{-1}$. The lithiophobic/lithiophilic interlayer enables solid-state metal batteries to simultaneously achieve high energy and long cycle life. (© 2023 Wiley‐VCH GmbH)