Wei Lu's blog

Our GM/UM Advanced Battery Coalition at the department of Mechanical Engineering, University of Michigan is recruiting highly motivated and independent postdoctoral researchers to study in the general field of advanced Li-ion batteries and their fading mechanisms. The candidate should hold a doctor degree in Mechanics, Materials, Chemistry, Physics, or a relevant discipline. Past experience with finite element analysis, atomistic simulations, and programming is preferred.

This paper proposes and implements a novel hybrid level set method which combines the

Coated nanoparticles, which have a core-shell structure, have many applications. The attached manuscript shows some of our progresses in investigating the induced torque and orientation of such nanoparticles in an electric field. We show that the shell of a nanoparticle has an important effect on its orientation, even when the shell is thin and takes only a small portion of the total volume. For instance, a thin layer coating of highly conductive Au can dramatically change the induced torque on a SiO2 or TiO2 nanoparticle.

Nanocomposite performance fundamentally relies on reproducible dispersion and arrangement of nanoparticles, such that the dominate morphology across macroscopic dimensions is also nanoscopic. To facilitate dispersion, chemical approaches, including surfactant or macromolecular stabilization are usually employed to modify the surface of nanoparticles. However, the approach depends on the material system and usually involves trial-and-error to identify the best practice. Much less quantitative information is available on the coupling between the surface modification and external processing factors, including shear, electric or magnetic fields. In a recent work, we considered electric field on the interaction of nano-plates. For ideal dielectrics an electric field may assist (or retard) exfoliation depending on the angle between a collection of plates and the field. A critical electric field strength to promote exfoliation is predicted when the field is parallel to the surface of the plates. Structural refinement is predicted to occur by cleavage through the center of the stack. For lossy dielectrics, frequency can be tuned to cause exfoliation in all plate orientations.