Comparison of (a) simulated and (b)-(c) observed lithiated diamond cores in LixFePO4 single particles.
My postdoc with Prof. Martin Bazant officially ended 6 years ago, but it’s still generating research papers! A paper that we wrote was just published at Electrochemistry Communications, and is available for free at this link until October 28.
Over that time we had been following the progress in advanced microscopy techniques applied to battery materials, and realized that our model of lithium iron phosphate captured many of the features researchers were imaging. The model helped resolve conflicting reports from different researchers who looked at a variety of different size LiFePO4 crystals. The smallest crystals at the nanoscale are controlled by their surface properties, while micron sized crystals are dominated by elastic energy. Just by running larger simulations we observed the transition that experimentalists were imaging. After a bunch of time invested on nights and weekends, this paper is finally finished.
A paper based on my thesis work was recently accepted to the journal Physical Chemistry Chemical Physics. I helped researchers at the IMDEA Materials Institute in Madrid, Spain apply the phase-field model from my thesis to the NiAl-Cr ternary eutectic superalloy. They connected my model to a database of thermodynamic properties and were able to simulate the growth of the complicated microstructure in this system. Superalloys are a special class of metals that are used to make jet turbine blades because they are very strong and resistant to deformation at high temperatures.
Read Formation mechanism of eutectic microstructures in NiAl-Cr composites
I recently had a Rapid Communication accepted at Physical Review E. This paper represents several years of effort while I was at Samsung to develop a model of the growth of metal dendrites during electrodeposition. In addition to looking pretty, understanding how these dendrites grow is important for making rechargeable batteries with significantly higher energy density than current technologies. The dendrites eventually cause a short-circuit during cycling when a metal electrode is used. In this paper I constructed a phase-field model that accurately captures many of the observed features of electrodeposits. This will be a valuable tool for mitigating dendrite growth, particularly for pulsed charging. The model provides an estimate of the time at which the interface becomes unstable, and could be used to optimize the pulse time while still maintaining a flat interface. The video on the right shows one of the simulations that is presented in the paper. The blue lines are electric field lines, which indicate the direction of migration of ions in the electrolyte (white). The video shows that, after a short period of stable growth, the interface becomes unstable. The electric field concentrates at protruding tips, causing them to grow faster and shield the nearby electrode. When the field at a tip gets too high, the tip splits and the process repeats. Quantitative phase-field modeling of dendritic electrodeposition