Revealing the Atomic Origin of Heterogeneous Li‐Ion Diffusion by Probing Na

Tracing the dynamic process of Li‐ion transport at the atomic scale has long been attempted in solid state ionics and is essential for battery material engineering. Approaches via phase change, strain, and valence states of redox species have been developed to circumvent the technical challenge of d...

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Bibliographic Details
Published in:Advanced materials (Weinheim) 2019-07, Vol.31 (29), p.e1805889-n/a
Main Authors: Xiao, Biwei, Wang, Kuan, Xu, Gui‐Liang, Song, Junhua, Chen, Zonghai, Amine, Khalil, Reed, David, Sui, Manling, Sprenkle, Vincent, Ren, Yang, Yan, Pengfei, Li, Xiaolin
Format: Article
Language:English
Subjects:
Batteries
Cathodes
Charge exchange
Diffusion layers
dislocation diffusion
Dislocations
Ion diffusion
ion exchange
Ion transport
layer diffusion
layered cathodes
lithium‐ion batteries
Phase transitions
Sodium
Spatial resolution
Valence
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Summary:Tracing the dynamic process of Li‐ion transport at the atomic scale has long been attempted in solid state ionics and is essential for battery material engineering. Approaches via phase change, strain, and valence states of redox species have been developed to circumvent the technical challenge of direct imaging Li; however, all are limited by poor spatial resolution and weak correlation with state‐of‐charge (SOC). An ion‐exchange approach is adopted by sodiating the delithiated cathode and probing Na distribution to trace the Li deintercalation, which enables the visualization of heterogeneous Li‐ion diffusion down to the atomic level. In a model LiNi1/3Mn1/3Co1/3O2 cathode, dislocation‐mediated ion diffusion is kinetically favorable at low SOC and planar diffusion along (003) layers dominates at high SOC. These processes work synergistically to determine the overall ion‐diffusion dynamics. The heterogeneous nature of ion diffusion in battery materials is unveiled and the role of defect engineering in tailoring ion‐transport kinetics is stressed. Electrochemically replacing the Li‐ions with Na‐ions in layered cathode materials enables direct visualization of the diffusion heterogeneities at the atomic scale using microscopic techniques. Dislocation diffusion and layer diffusion are observed in a model LiNi1/3Mn1/3Co1/3O2 material and the correlation with state of charge is revealed.
ISSN:0935-9648
1521-4095
DOI:10.1002/adma.201805889