Solid-state electrolytes have been discovered as an alternative to liquid electrolyte on lithium-based batteries. Among all solid electrolytes, poly (ethylene oxide) based-solid electrolytes (PEO) have the advantages of low flammability, good flexibility, and excellent thermal stability. The major problem limiting the rate capability of PEO-based electrolyte in the lithium metal battery during charging is the issue of lithium penetration through the PEO electrolyte that results in short circuits 1. To overcome these drawbacks, we have added the ceramic fillers (i.e., garnet (Li7La3Zr2O12) etc.) in a ratio of 10-40% in the polymer host matrix. The garnet ceramic filler contributes to reduce the crystallinity of polymer and so to increase the ionic conductivity. The ceramic in polymer also provides higher mechanical strength that can reduce the lithium dendrite formation 2. To investigate the formation of lithium dendrite, we show a detailed study of lithium metal deposition on the LLZO-PEO electrolyte using ex-situ electrochemical and electron microscopic methods. Keywords: Solid-state lithium batteries, Solid polymer electrolyte, Garnet, Polymer-ceramic composite electrolyte, Lithium dendrite REFERENCES 1. J. Mindemark, M. J. Lacey, T. Bowden and D. Brandell, Progress in Polymer Science, 2018, 81, 114-143.2. W. Zhang, J. Nie, F. Li, Z. L. Wang and C. Sun, Nano Energy, 2018, 45, 413-419. Figure 1