Improved Electrochemical Performance of Al2O3-Coated LiNi0.6Mn0.2Co0.2O2 Cathodes By Atomic Layer Deposition

Abstract

There has been an ever-increasing need on high-energy and cost-effective lithium-ion batteries (LIBs) in order to power future transportation. In this context, LiNi1-x-yMnxCoyO2 (NMC) cathodes are particularly attractive, due to their reduced cost and higher capacity compared to the traditional LiCoO2 cathodes [1]. Among the NMC cathodes, nickel-rich LiNi0.6Co0.2Mn0.2O2 (NMC622) is one of the most promising cathode materials undergoing intensive investigation, but suffers from a series of technical issues, such as dissolution of metal elements, oxygen evolution, and structural instability [2]. Aimed at addressing these issues, we recently applied Al2O3 coatings on NCM622 using atomic layer deposition (ALD). Unlike others did, we coated the cathode directly and it revealed that the ALD Al2O3 coatings enable improving the cyclability and sustainable capacity of the NMC622 cathodes at different cutoff voltages of 4.3 – 4.7 V. In the study, we investigated the effects of ALD Al2O3 coatings using X-ray diffraction, X-ray photoelectron spectroscopy, impedance spectroscopy, scanning electron microscopy, and transmission electron microscopy. Our study demonstrated that ALD remains an important measure to tackle technical issues in LIBs [3]. Manthiram, A., B. Song, and W. Li, A perspective on nickel-rich layered oxide cathodes for lithium-ion batteries. Energy Storage Materials, 2017. 6: p. 125-139.Hou, P., et al., Surface/Interfacial Structure and Chemistry of High-Energy Nickel-Rich Layered Oxide Cathodes: Advances and Perspectives. Small, 2017. 13(45): p. 1701802.Meng, X., X.-Q. Yang, and X. Sun, Emerging applications of atomic layer deposition for lithium-ion battery studies. Advanced Materials, 2012. 24(27): p. 3589-3615. Figure 1