Li/Garnet Interface Stabilization by Thermal‐Decomposition Vapor Deposition of an Amorphous Carbon Layer

Abstract Applying interlayers is the main strategy to address the large area specific resistance (ASR) of Li/garnet interface. However, studies on eliminating the Li 2 CO 3 and LiOH interfacial lithiophobic contaminants are still insufficient. Here, thermal‐decomposition vapor deposition (TVD) of a carbon modification layer on Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 (LLZTO) provides a contaminant‐free surface. Owing to the protection of the carbon layer, the air stability of LLZTO is also improved. Moreover, owing to the amorphous structure of the low graphitized carbon (LGC), instant lithiation is achieved, and the ASR of the Li/LLZTO interface is reduced to 9 Ω cm 2 . Lithium volatilization and Zr 4+ reduction are also controllable during TVD. Compared with its high graphitized carbon counterpart (HGC), the LGC‐modified Li/LLZTO interface displays a higher critical current density of 1.2 mA cm −2 , as well as moderate Li plating and stripping, which provides enhanced polarization voltage stability.