The effects of ambient storage conditions on the structural and electrochemical properties of NMC-811 cathodes for Li-ion batteries

High-Ni cathode materials are prone to reactivity and instability upon exposure to ambient levels of humidity. This has implications for the storage and processing of cathodes for Li-ion batteries (LIBs), in order to avoid any premature degradation of the material prior to operation. NMC-811 materials were subjected to differing degrees of exposure to ambient humidity, in order to establish the impact this would have on electrochemical performance. This study used a combination of physical, chemical and electrochemical methods to investigate the operational effects that moisture can have on the battery accordingly. Longer term cycling, d-SIMS and microscopy were used to characterise the degradation phenomena and relating to capacity fade. Post-mortem analysis revealed that the structural breakdown of the secondary particles is a dominant factor that influences charge transfer resistance increases. The study highlights the criticality of how high Ni materials are handled during storage and processing, in order to mitigate premature degradation events during operation. (c) 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/ )

Automated summary

High-Ni cathode materials are reactive and unstable when exposed to ambient humidity, affecting the storage and processing of Li-ion batteries. A study using various methods investigated the impact of humidity on battery performance, emphasizing the importance of handling high Ni materials properly.