Stability of LiNi_0.6Mn_0.2Co_0.2O₂ as a Cathode Material for Lithium‐Ion Batteries against Air and Moisture

Abstract

LiNi 0.6 Co 0.2 Mn 0.2 O 2 (C622), a Ni-rich cathode material, was prepared and its durability tested in air and moisture. For the test, C622 was stored in a glovebox and in a humidity chamber at 50% RH. For each sample, the cell performance was tested in terms of the specific capacity, rate capability, and cycling stability; the changes in the crystal structure were also investigated. The results indicate that when C622 is stored in a humidity chamber, severe degradation occurs in all measurements relating to the cell performance, whereas when it is stored in a glovebox, no degradation is seen. This indicates that C622 is very sensitive to air and moisture. A larger quantity of residual lithium compounds, which are by-products of the reaction between the cathode material, CO 2 , and moisture in the air, could be seen on the surface of the C622 that was stored in a humidity chamber when compared to the one stored in a glovebox. The formation of residual lithium compounds and the corresponding changes in the crystal structure of C622 kept in the humidity chamber may be the reason for the degradation in the cell performance.

Current and future lithium-ion battery manufacturing

“…Other water-based binders such as cellulose and lignin-based polymers are also low-cost choices, which could be easily processed from natural products ( Nirmale et al., 2017 ). However, most of the cathode materials are sensitive to water, especially the layered oxide cathode ( Park et al., 2016 ). Immersing the cathode materials in water can cause severe degradation because of the surface structure change and the formation of alkaline lithium compounds (Li 2 CO 3 , LiOH), which will corrode the aluminum collector.…”

Performance and ageing behavior of water-processed LiNi0.5Mn0.3Co0.2O2/Graphite lithium-ion cells

“…Yet, mixing the electrode components in water raises some challenges to obtain electrodes with comparable properties to those processed in NMP, notably because lithium transition metal oxides such as NMC material are prone to react with water. Upon contact with moisture, the surface of NMC particles is altered, notably by the formation of LiOH and Li2CO3 species [3][4][5] . Besides, lithium leaching has been reported, sometimes along with Li + /H + cation exchange reaction 4,6 , and it is believed to trigger the formation of a rock-salt phase on the outer layers of the particles 6,7 .…”

Surface/Interfacial Structure and Chemistry of High‐Energy Nickel‐Rich Layered Oxide Cathodes: Advances and Perspectives

“…The contact with H 2 O and CO 2 in ambient air makes the formation of LiOH and Li 2 CO 3 as indicated in Figure a. [25b,26,88a] During storage, the spontaneous reaction of Ni 3+ to Ni 2+ is also likely to take place, which might cause a loss in structural ordering as shown in Figure b. In addition, these nickel‐rich electrodes' structural evolutions would increase electrochemical impedance and block the Li + diffusion during redox, which would further result in the fats decay of electrochemical properties after storage in air for a period of time as revealed in Figure c.…”

“…Reproduced with permission. [88a] Copyright 2016, KCS Publications. d) Gassing during a typical formation cycle.…”