One-Step Processing of Soft Electrolyte/Metallic Lithium Interface for High-Performance Solid-State Lithium Batteries

Cubic garnet-type Li7La3Zr2O12 (LLZO) is a remarkable Li-ion electrolyte for solid-state lithium metal batteries due to its high ion conductivity and perfect electrochemical stability against lithium metal anode. However, the application of LLZO is hindered by the poor interfacial contact between garnet and lithium metal. Herein, LLZO powder was sandwiched by graphite foils and densified by a one-step hot press process. After peeling off the graphite foils from the LLZO pellet, the residual thin layer of graphite (∼0.15 μm) can be easily lithiated in contact with lithium metal. This buffer layer not only greatly improves the wettability and interfacial contact between LLZO and lithium metal but also significantly relieves the volume expansion of lithium metal during cycling. The assembled symmetric cell cycled over 1500 h at 0.1 mA cm–2 with excellent stability. Moreover, the hybrid-state full cell also shows good electrochemical performance.