Investigation of Moisture Content, Structural and Electrochemical Properties of Nickel-Rich NCM Based Cathodes Processed at Ambient Atmosphere

Abstract

For batteries with high energy density and good fast-charge capability, NCM cathode active materials with ≥80 mol% nickel are promising due to their high specific capacities. Unfortunately, the increase in nickel content is accompanied by a high susceptibility to moisture. Therefore, nickel-rich NCM is coated or doped by the manufacturers to increase its stability. However, it is unclear if special requirements regarding ambient humidity must still be met during the whole production chain, or only after post-drying and during cell assembly. Therefore, the structure and properties of three different nickel-rich NCM active materials (one doped monocrystalline, two coated polycrystalline materials) processed at ambient atmosphere were investigated. At every process step, moisture content and microstructure were examined. Prior to cell assembly, two different post-drying procedures were applied and investigated. As validation, electrochemical tests were performed. Both polycrystalline cathodes demonstrated good physical and electrochemical properties, despite the ambient process atmosphere. Higher moisture reduction led to improved electrochemical performances at higher C-rates. Finally, a comparison between dry and normal atmosphere of the best performing material indicates that a production of high-quality nickel-rich electrodes at ambient atmosphere is possible if their exposure to moisture is short and well-designed post-drying techniques are applied.