Tuning Interface Lithiophobicity for Lithium Metal Solid-State Batteries

Solid-state lithium batteries (SSLBs) using garnet electrolytes potentially have a higher energy density and are safer than liquid organic electrolyte Li-ion batteries. However, SSLBs face challenges of Li dendrite and high interface resistance. In this work, we overcome both challenges by doping strontium (Sr) into lithium anodes. Different from all previous metal/metal oxide coating on garnet or Li alloy anodes that form lithiophilic interlayer, Li–Sr/SrO-doped Li 2 O are enriched on the interface forming a lithiophilic/lithiophobic bifunctional layer. The interlayer reduces the interfacial resistance and also suppresses lithium dendrite. The stability of the lithiophobic SrO-doped Li 2 O against Li prevents reducing the garnet and suppresses Li dendrite, which distinguishes it from all reported alloy electron-conducting interlayers. The optimized Li–Sr|garnet|Li–Sr symmetric cell achieves a critical current density of 1.3 mA/cm 2 and can be cycled for 1,000 cycles under 0.5 mA/cm 2 at room temperature. The bifunctional lithiophilic/lithiophobic interlayer provides a new strategy for high-performance garnet solid-state lithium batteries.