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Title: Visualization of anisotropic-isotropic phase transformation dynamics in battery electrode particles

Authors:
; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1354616
Report Number(s):
BNL-113133-2016-JA
Journal ID: ISSN 2041-1723
DOE Contract Number:
SC00112704
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature Communications; Journal Volume: 7
Country of Publication:
United States
Language:
English

Citation Formats

Wang, Jiajun, Karen Chen-Wiegart, Yu-chen, Eng, Christopher, Shen, Qun, and Wang, Jun. Visualization of anisotropic-isotropic phase transformation dynamics in battery electrode particles. United States: N. p., 2016. Web. doi:10.1038/ncomms12372.
Wang, Jiajun, Karen Chen-Wiegart, Yu-chen, Eng, Christopher, Shen, Qun, & Wang, Jun. Visualization of anisotropic-isotropic phase transformation dynamics in battery electrode particles. United States. doi:10.1038/ncomms12372.
Wang, Jiajun, Karen Chen-Wiegart, Yu-chen, Eng, Christopher, Shen, Qun, and Wang, Jun. 2016. "Visualization of anisotropic-isotropic phase transformation dynamics in battery electrode particles". United States. doi:10.1038/ncomms12372.
@article{osti_1354616,
title = {Visualization of anisotropic-isotropic phase transformation dynamics in battery electrode particles},
author = {Wang, Jiajun and Karen Chen-Wiegart, Yu-chen and Eng, Christopher and Shen, Qun and Wang, Jun},
abstractNote = {},
doi = {10.1038/ncomms12372},
journal = {Nature Communications},
number = ,
volume = 7,
place = {United States},
year = 2016,
month = 8
}
  • Anisotropy, or alternatively, isotropy of phase transformations extensively exist in a number of solid-state materials, with performance depending on the three-dimensional transformation features. Fundamental insights into internal chemical phase evolution allow manipulating materials with desired functionalities, and can be developed via real-time multi-dimensional imaging methods. In this paper, we report a five-dimensional imaging method to track phase transformation as a function of charging time in individual lithium iron phosphate battery cathode particles during delithiation. The electrochemically driven phase transformation is initially anisotropic with a preferred boundary migration direction, but becomes isotropic as delithiation proceeds further. We also observe the expectedmore » two-phase coexistence throughout the entire charging process. Finally, we expect this five-dimensional imaging method to be broadly applicable to problems in energy, materials, environmental and life sciences.« less
  • Using a novel statistical approach that efficiently explores the space of possible defect configurations, our present study investigates the chemomechanical coupling between interfacial structural defects and phase boundary alignments within phase-separating electrode particles. Applied to the battery cathode material Li XFePO 4 as an example, the theoretical analysis reveals that small, defect-induced deviations from an ideal interface can lead to dramatic shifts in the orientations of phase boundaries between Li-rich and Li-lean phases, stabilizing otherwise unfavorable orientations. Significantly, this stabilization arises predominantly from configurational entropic factors associated with the presence of the interfacial defects rather than from absolute energetic considerations.more » The specific entropic factors pertain to the diversity of defect configurations and their contributions to rotational/orientational rigidity of phase boundaries. Comparison of the predictions with experimental observations indicates that the additional entropy contributions indeed play a dominant role under actual cycling conditions, leading to the conclusion that interfacial defects must be considered when analyzing the stability and evolution kinetics of the internal phase microstructure of strongly phase-separating systems. Possible implications for tuning the kinetics of (de)lithiation based on selective defect incorporation are discussed. Ultimately, this understanding can be generalized to the chemomechanics of other defective solid phase boundaries.« less
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  • The effects of compacting methods, heat treatment and chemical additives on the magnetic properties of NdFeB articles have been studied. Five sets of NdFeB powder articles, doped with different amounts of Dy from 0.1--2.9 wt%, are prepared in powder form by gas atomization and annealed at 650--750 C for 600 seconds under an inert argon atmosphere. These were then bonded in epoxy, either in isotropic form, or aligned during fabrication under the action an applied magnetic field. The results showed that the combined effects of the addition of Dy and heat treatment could dramatically improve the coercive force, remanent magnetizationmore » and maximum energy product. The results have been interpreted using a model of hysteresis which takes into account energy losses, anisotropy and texture of a material. The modeling showed that these effects alter the magnetic properties by increasing the hysteresis loss via the loss coefficient and by reducing the reversible component of magnetization through the reversibility coefficient. The compacting process influences the density of the particles in the bonded magnet which alters the magnetic properties through the coupling coefficient. The major influence of particle alignment can be interpreted as a change in the texture which can be described by a texture parameter.« less