Solid-state electrolytes (SSEs) have been considered as the ultimate solution to the issues of Li anodes in liquid electrolytes by fundamentally changing the deposition behavior of Li. These non-liquid systems are designed to be lighter and to block Li dendrites, which enable a safer Li metal battery with a higher energy density. Furthermore, the SSEs can negate the polysulfide shuttling issues that plague the Li-S batteries. To advance SSEs, development of new materials with a high ionic conductivity that is stable, scalable and compatible to electrode materials are critically required. Here, we developed a large scale 2D MoS2 films and fabricated micro channel by a conventional photolithography process. We measured unusually high ionic conductivity of metal ions in 2D MoS2 film and studied its ion transport mechanism by experimental and computational approaches. The 2D MoS2 also has been applied in a passivation layer of Li-metal and its battery performance has been scrutinized.This talk will present two subjects, synthesis of tunable large scale 2D MoS2 film and ion transport characterization, and its application in high efficiency Li-metal batteries. Our approach can lead to the realization of high energy density and safe Li-metal batteries. The study will guide the development of future ion transport devices such as SSE rechargeable batteries, neuromorphic devices and ion sensors owing to the facile and scalable device fabrication with superionic conductivity. References Advances of 2D MoS2 for High-Energy Lithium Metal Batteries, E Cha, DK Kim, W Choi, Frontiers in Energy Research 9, 44 (2021)Mixed Phase 2D Mo0.5W0.5S2 Alloy as Multi-Functional Electrocatalyst for the High-Performance Cathode in Li-S Batteries, S Bhoyate, J Kim, E Lee, B Park, E Lee, J Park, S Oh, J Kim, W Choi, 8, 12436 Journal of Materials Chemistry A (2020).2D MoS2 as an efficient protective layer for lithium metal anodes in high performance Li-S batteries, Cha, E., Patel, Cho, K., and Choi, W., Nature Nanotechnology, 13, pages337–344 (2018)Nanoengineering to achieve high efficiency practical lithium-sulfur batteries, Eunho Cha, Mumukshu Patel, Vish Prasad, Wonbong Choi, Nanoscale Horizons5(5):808-831 (2020). Figure 1