Phase field crystal model

Phase field crystal model

Charging a Li-battery, involves insertion (extraction) of Li-ions from electrode materials. This intercalation of the diffusing species (Li-ion) induces lattice transformational strains in the host material (electrode). In this project, I develop a Cahn-Hilliard phase field crystal model, which couples the composition field of the diffusing species with the host lattice symmetry. The modeling approach provides atomistic insights on lattice distortions and defect formations induced by Li-diffusion.

Here is an example of the phase transition showing structural evolution of lattices from a hexagonal (in blue), to a square symmetry (in red).

The model is applied to describe lattice deformation in a nanoparticle electrode during an electrochemical cycle. In the video below (left), Li-ions diffuse into the electrode particle and are illustrated by the changing composition field, c). On the right-side, the lattice-arrangements in the host electrode material are illustrated to evolve during the cycle. The triple-junction drag-effect (A) and grain-boundary migration (B) can be observed.

Collaborators: W. Craig Carter Massachusetts Insitute of Technology, USA                           Yet-Ming Chiang Massachusetts Insitute of Technology, USA

Related references
Cahn-Hilliard phase field crystal model Application to lithium batteries

Note pdfs (preprints) of these papers are available for educational purposes on the publications page