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

Abstract

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. Here, 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 expected two-phase coexistence throughout the entire charging process. We expect this five-dimensional imaging method to be broadly applicable to problems in energy, materials, environmental and life sciences.

Size-dependent phase morphologies in LiFePO4 battery particles

“…The lithiated diamond core morphology [8][9][10][11][12][13][14][15]17] is another intriguing feature in micron particles that is captured by our model. Fig.…”

Phase transformation mechanism in lithium manganese nickel oxide revealed by single-crystal hard X-ray microscopy

“…Research on scientific big data mining methods aiming for more effective analysis and better interpretation of the X-ray spectro-microscopic data has also been actively pursued24252627. Recent studies successfully utilized these advances in FF-TXM-XANES, and revealed the nucleation and growth process of new phases as a function of Li content in conventional secondary cathode particles, including LFP28293031, LiMn 2 O 4 (ref. 32), FeF 3 (ref.…”

Nanoscale x-ray and electron tomography

“…17 , 18 Combined with its fast imaging speed, TXM enables a 3D view of the chemical and structural evolution of a dynamical system and provides critical insights into the underlying mechanisms of materials evolution. 19 Electron tomography (ET) operates in a similar manner to x-ray imaging-based tomography. In the (scanning) transmission electron microscope (S/TEM), projection images of a nanoscale sample are taken in either the full-field transmission mode or the scanning mode with a focused scanning beam.…”