Miscibility Gap Closure, Interface Morphology, and Phase Microstructure of 3D Li(x)FePO4 Nanoparticles from Surface Wetting and Coherency Strain.
We study the mesoscopic effects which modify phase-segregation in LixFePO4 nanoparticles using a multiphysics phase-field model implement on a high performance cluster. We simulate 3D spherical particles of radii from 3 to 40 nm and examine the equilibrium microstructure and voltage profiles as they depend on size and overall lithiation. The model includes anisotropic, concentration-dependent elastic moduli, misfit strain, and facet dependent surface wetting within a Cahn-Hilliard formulation. We find that the miscibility gap vanishes for particles of radius ∼5 nm, and the solubility limits change with overall particle lithiation. Surface wetting stabilizes minority phases by aligning them with energetically beneficial facets. The equilibrium voltage profile is modified by these effects in magnitude, and the length and slope of the voltage plateau during two-phase coexistence.
Materials Science Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
Michael J
MJ
Welland
Computation Institute, University of Chicago , Chicago, Illinois 60637, United States.
Dmitry
D
Karpeyev
McCormick School of Engineering, Northwestern University , Evanston, Illinois 60208, United States.
Devin T
DT
O'Connor
Materials Science Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.|Computation Institute, University of Chicago , Chicago, Illinois 60637, United States.|Northwestern-Argonne Institute for Science and Engineering , Evanston, Illinois 60208, United States.
Olle
O
Heinonen
Li-ion battery; LiFePO4; coherency strain; interface morphology; nanoparticles; phase-field model; surface wetting