In situ construction of a multifunctional interlayer for garnet-type electrolytes to suppress lithium dendrite formation in solid-state lithium batteries

Garnet-type solid-state electrolytes (SSEs) have great potential to be applied in all-solid-state lithium batteries (ASSLBs) due to their high ionic conductivity and excellent electrochemical stability with Li metal. However, the poor interface contact and the high electronic conductivity issues resulting in lithium dendrites growth remain challenging. Herein, we constructed a multifunctional interlayer LiF/Li-Ag alloy (LFA) in situ on the surface of garnet-type Li6.5La3Zr1.5Ta0.5O12 (LLZTO) to suppress Li dendrite growth. The matrix of the interlayer is a three-dimensional porous structure LiF and it is filled with Li-Ag alloy. The LiF blocks electron access to the LLZTO and the Li-Ag alloy ensures a good interface contact during cycling. The Li/LFA-LLZTO/Li symmetrical cells exhibit an ultralow interfacial resistance of 1.8 Ω cm2, a high critical current density of 1.1 mA cm−2 and outstanding galvanostatic cycling stability at 0.2 mA cm−2 for 2000 h. Moreover, the LiFePO4/LFA -LLZTO/Li full cell delivers a high discharge capacity of 155 mAh g−1 at 0.1 C with a capacity retention of 93% after 100 cycles.