Abstract：

The phase-field approach has become a very powerful computational tool for the study of microstructure in materials. By introducing the field variables, it allows naturally tracking of the evolution of interfaces which are essential to the complex microstructures of functional materials. Other advantages of the phase-field approach include its flexibility of combining different field variables and adding new physics. In this presentation an introduction will be given on the phase field theory, its fundamentals and classification. The author’s research fields focus on finite element phase field modeling of ferroelectrics, ferromagnetics and Li-ion battery materials.
In this work, the author will present phase field modeling of electro-chemo-mechanical behavior of electrode materials in Lithium-ion batteries. Lithium-ion batteries are the predominant power source for portable electronic devices such as cellphones and tablet PCs and potentially for Plug-in hybrid electric vehicles. One major key factor, which limits the performance of the batteries, is the high mechanical stress and the induced fracture in the active materials of the electrodes. Over several hundred charge-discharge cycles at a relative high charging rate this causes material fatigue of the electrodes, cracking and a literal pulverization of the active material, accompanied by capacity loss of the battery cell. A phase field fracture model will be presented, which deals in a consistent fashion with the phase segregation, mechanics, fracture, and electrochemical reaction at particle and fracture surfaces. For the solution of the higher-order nonlinear equation system, 3D isogeometric finite element implementation has been carried out. Simulation results will be presented to show the influence of factors such as geometry, anisotropy, surface energy and charge rate on the chemo-mechanical behavior of electrode particles.

Brief CV:

Bai-Xiang Xu, Professor and Head of Research Group Mechanics of Functional Materials, Institute of Materials Science, Technical University of Darmstadt (TU Darmstadt), Germany, received his Ph.D in 2008 from Peking University. Before joining the faculty at TU Darmstadt in 2011, Dr. Xu worked as Postdoc at TU Kaiserslautern and TU Darmstadt as a Humboldt fellowship holder. Dr Xu’s research focuses on continuum modeling and numerical simulation of functional materials and systems, for example ferroelectric ceramics, ferromagnetics, active materials in lithium ion batteries and deformable dielectrics. She has authored/co-authored over 50 referred journal papers, and the results are cited over 500 times.

Bai-Xiang Xu (胥柏香)
Mechanics of Functional Materials, Institute of Materials Science, Technical University of Darmstadt, Germany
E-mail: xu@mfm.tu-darmstadt.de