An in situ-formed high lithiophilic solid lubricant interface layer for garnet-based solid-state lithium metal batteries

The garnet-type oxides electrolyte triggers immense interests owing to their potential to replace liquid electrolytes and excellent safety in lithium metal battery. But the huge interfacial resistance and unlimited dendrite growth remain challenging. Here, we introduce a new high lithiophilic solid lubricant interface layer, which composes of LiF, amorphous carbon and (CFX)n. The (CFX)n, exhibiting excellent lithium affinity and combining with solid lubricant characteristic, adheres well to Li anode during the long-term cycle. Most remarkably, the in situ-formed LiF and amorphous carbon guarantee uniform ion and electron transportation. Symmetric cells composed of (CFX)n modified garnet electrolyte exhibit an enormously reduced interfacial impedance of 5 Ω cm2 and long-term outstanding plating/stripping cycle up to 2900 h at 0.38 mA/cm2. Moreover, full LiFePO4|CF-garnet electrolyte|Li cells demonstrate excellent cycling efficiency, high specific capacity and long-term stability over 700 cycles at 2C.