Lithium anode interlayer design for all-solid-state lithium-metal batteries

All-solid-state lithium-metal batteries (ASSLBs) have attracted intense interest due to their high energy density and high safety. However, Li dendrite growth and high interface resistance remain challenging due to insufficient understanding of the mechanism. Here we develop two types of porous lithiophobic interlayer (Li₇N₂I–carbon nanotube and Li₇N₂I–Mg) to enable Li to plate at the Li/interlayer interface and reversibly penetrate into the porous interlayer. The experimental and simulation results reveal that a balance of lithiophobicity, electronic and ionic conductivities and interlayer’s porosity are the key enablers for stable Li plating/stripping at a high capacity. A fine-tuned Li₇N₂I–carbon nanotube interlayer enables Li/LNI/Li symmetric cell to achieve a high critical current density of 4.0 mA cm⁻² at 4.0 mAh cm⁻² at 25 °C; the Li₇N₂I–Mg interlayer enables a Li₄SiO₄@LiNi_0.8Mn_0.1Co_0.1O₂/Li₆PS₅Cl/20 µm-Li full cell to achieve an areal capacity of 2.2 mAh cm⁻², maintaining 82.4% capacity retention after 350 cycles at 60 °C at a rate of 0.5 C. The interlayer design principle opens opportunities to develop safe and high energy ASSLBs.