Due to its higher capacity compared to the commercialized LiNixMnyCo1-x-yO2 (NMCs, 0< x, y <1) with lower Ni content (x≤0.6), LiNi0.8Mn0.1Co0.1O2 (NMC811) is now considered as the next promising cathode for lithium-ion batteries (LIBs). However, it still suffers from more serious performance degradation and safety hazard than the commercial ones. These existing issues are reflected as cation mixing, oxygen evolution, irreversible phase-transition, transition metal ion dissolution, and microcracking. Aimed at addressing these problems, surface coating has proven to be an important and effective approach. In recent years, atomic layer deposition (ALD) has emerged as an accurate tool to apply uniform and conformal coatings over NMCs at the atomic level, which have shown remarkable effects on the improved performance of batteries.1-4 Herein, for the first time we deposited ultrathin ALD Li2S coatings5 conformally over NMC811 composite electrodes. It was found that the ALD Li2S coatings enable to enhance performance of NMC811 cathodes with much better cyclability and rate capability. To clarify the effects of the ALD Li2S coatings, we utilized a suite of characterization tools including X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy, and transmission X-ray microscopy. The results revealed that the ALD Li2S coatings can perfectly maintain the NMC structure during cycling, thus significantly suppress the crack formation. Furthermore, the Li2S layer can react with and eliminate H2O in electrolyte and O2 released from the NMC structure. In addition, the measurements of electrochemical impedance spectroscopy were applied, which confirms that the Li2S coatings serve as physical protection layers to prevent the interfacial reactions between the NMC cathode and liquid electrolyte. It can be foreseen that sulfides would be a new class of coating materials for addressing issues of NMC cathodes.1. Meng, X.; Yang, X. Q.; Sun, X. L., Advanced Materials 2012, 24 (27), 3589-3615.2. Liu, Y.; Wang, X.; Cai, J.; Han, X.; Geng, D.; Li, J.; Meng, X., Journal of Materials Science & Technology 2020, 54, 77-86.3. Wang, X.; Cai, J.; Liu, Y.; Han, X.; Ren, Y.; Li, J.; Liu, Y.; Meng, X., Nanotechnology 2020, 32 (11), 115401.4. Gao, H.; Cai, J.; Xu, G.-L.; Li, L.; Ren, Y.; Meng, X.; Amine, K.; Chen, Z., Chem. Mater. 2019, 31 (8), 2723-2730.5. Meng, X.; Comstock, D. J.; Fister, T. T.; Elam, J. W., ACS Nano 2014, 8 (10), 10963-10972.