Abstract
Single crystal, Ni-rich layered lithium metal oxides are promising candidates for next-generation cathodes in lithium-ion batteries. However, these Ni-rich materials display anisotropic swelling and contraction during cycling, and this may lead to the generation of internal stresses and thereby to fracture and capacity loss. In this work, the spatio-temporal evolution of lithium concentration and stress state within a
LiNi
0.8
Mn
0.1
Co
0.1
O
2
(NMC811) single crystal are predicted using a fully coupled chemo-mechanical model. The stress state in the crystal arises from a spatially non-uniform distribution of Li concentration, and from a non-linear dependence of intercalation strain upon lithium concentration. The peak tensile stress is greatest near top-of-charge, due to the high sensitivity of intercalation strain upon lithium occupancy at low concentrations, and the peak tensile stress increases with both cycling rate and particle dimension. Significantly, the predicted peak tensile stress is insufficient to cause basal plane fracture of single crystals when their diameter is below 2.5 μm and the charging and discharging rates are below 5C. This suggests that intraparticle fracture is not a significant degradation mode for well-designed NMC811 single crystals.
Funder
ERC Advanced Investigator Grant
Faraday Institution
European Research Council
Publisher
The Electrochemical Society
Subject
Materials Chemistry,Electrochemistry,Surfaces, Coatings and Films,Condensed Matter Physics,Renewable Energy, Sustainability and the Environment,Electronic, Optical and Magnetic Materials
Cited by
4 articles.
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