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Title: Phase-field modeling of diffusional phase behaviors of solid surfaces: A case study of phase-separating Li XFePO 4 electrode particles

In this paper, we present a comprehensive phase-field model for simulating diffusion-mediated kinetic phase behaviors near the surface of a solid particle. The model incorporates elastic inhomogeneity and anisotropy, diffusion mobility anisotropy, interfacial energy anisotropy, and Cahn–Hilliard diffusion kinetics. The free energy density function is formulated based on the regular solution model taking into account the possible solute-surface interaction near the surface. The coherency strain energy is computed using the Fourier-spectral iterative-perturbation method due to the strong elastic inhomogeneity with a zero surface traction boundary condition. Employing a phase-separating Li XFePO 4 electrode particle for Li-ion batteries as a model system, we perform parametric three-dimensional computer simulations. The model permits the observation of surface phase behaviors that are different from the bulk counterpart. For instance, it reproduces the theoretically well-established surface modes of spinodal decomposition of an unstable solid solution: the surface mode of coherent spinodal decomposition and the surface-directed spinodal decomposition mode. We systematically investigate the influences of major factors on the kinetic surface phase behaviors during the diffusional process. Finally, our simulation study provides insights for tailoring the internal phase microstructure of a particle by controlling the surface phase morphology.
 [1] ;  [2] ;  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Materials Science Division
  2. Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering
Publication Date:
Report Number(s):
Journal ID: ISSN 0927-0256
Grant/Contract Number:
AC52-07NA27344; CMMI-1235092
Accepted Manuscript
Journal Name:
Computational Materials Science
Additional Journal Information:
Journal Volume: 108; Journal Issue: B; Journal ID: ISSN 0927-0256
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pennsylvania State Univ., University Park, PA (United States)
Sponsoring Org:
USDOE; LLNL Laboratory Directed Research and Development (LDRD) Program; National Science Foundation (NSF)
Country of Publication:
United States
36 MATERIALS SCIENCE; 25 ENERGY STORAGE; phase-field model; solid surface; phase behavior; electrode particle
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1250075