Two-dimensional lithium diffusion behavior and probable hybrid phase transformation kinetics in olivine lithium iron phosphate
Author(s)Hong, Liang; Li, Linsen; Chen-Wiegart, Yuchen-Karen; Wang, Jiajun; Xiang, Kai; Gan, Liyang; Li, Wenjie; Meng, Fei; Wang, Fan; Wang, Jun; Chiang, Yet-Ming; Jin, Song; Tang, Ming; ... Show more Show less
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Olivine lithium iron phosphate is a technologically important electrode material for lithium-ion batteries and a model system for studying electrochemically driven phase transformations. Despite extensive studies, many aspects of the phase transformation and lithium transport in this material are still not well understood. Here we combine operando hard X-ray spectroscopic imaging and phase-field modeling to elucidate the delithiation dynamics of single-crystal lithium iron phosphate microrods with long-axis along the  direction. Lithium diffusivity is found to be two-dimensional in microsized particles containing ∼3% lithium-iron anti-site defects. Our study provides direct evidence for the previously predicted surface reaction-limited phase-boundary migration mechanism and the potential operation of a hybrid mode of phase growth, in which phase-boundary movement is controlled by surface reaction or lithium diffusion in different crystallographic directions. These findings uncover the rich phase-transformation behaviors in lithium iron phosphate and intercalation compounds in general and can help guide the design of better electrodes.
DepartmentMassachusetts Institute of Technology. Department of Materials Science and Engineering; Massachusetts Institute of Technology. Department of Physics
Nature Publishing Group
Hong, Liang et al. “Two-Dimensional Lithium Diffusion Behavior and Probable Hybrid Phase Transformation Kinetics in Olivine Lithium Iron Phosphate.” Nature Communications 8, 1 (October 2017): 1194 © 2017 The Author(s)
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