Study of graphite interlayer modification on the interfacial stability of solid electrolyte Li7La3Zr2O12 with lithium metal anode

The instability of Ta-doped Li 7 La 3 Zr 2 O 12 (LLZTO) solid electrolytes with Li anode has severely restricted the development of all-solid-state lithium batteries. Herein, a simple interlayer of graphite is constructed at the Li/LLZTO interface with pencil, and the electrochemical stability of the battery has been significantly improved. Results show that the internal resistance of battery modified by 2B type graphite interlayer is reduced more than 2 orders of magnitude than that of the unmodified battery. And the battery has good cycling stability at current density of 0.1 mA cm −2 with polarization voltage< 0.01 V after 200 cycles. Besides, it also has excellent high-current discharge performance in the range of 0.1 mA cm −2 ∼ 0.6 mA cm −2 with polarization voltage close to 0 V. SEM showed that before galvanostatic charge-discharge (GCD) cycle, the morphology of the surface graphite is lamellar, while it is irregular granular shape and appeared at the grain boundary of LLZTO solid electrolyte after GCD cycle. Raman and XPS results shows that a LiC 6 compound is formed after GCD cycle, which locally form LiC 6 /LLZTO/LiC 6 microbatteries, where Li + can spontaneously diffuse in the in-situ lithiated graphite layer, thereby enhancing the electrochemical performance of the battery.