Li-ion battery performance is usually limited due to diffusion losses in active materials (Graphite, NCM etc.). The transport parameter (diffusion coefficient) for Li in solid material is mostly measured using an established technique where a pulse of current is sent to the battery and voltage is measured and obtained voltage values are fitted to a simple formula. Such techniques are applicable for systems that can be described as behaving 'linearly' (i.e. concentration is linearly proportional to chemical potential). Battery materials rarely show linear behavior. Hence the existing technique needs to be modified to account for the transport characteristics of battery materials and a correct method/technique needs to be proposed.
The project will require familiarity with transport phenomena (fick's second law), familiarity with matlab/python and Mathematica/Maple.
The seminal papers on the topic of measuring diffusion coefficient:
1. Wen, C.J., Boukamp, B.A., Huggins, R.A. and Weppner, W., 1979. Thermodynamic and mass transport properties of “LiAl”. Journal of The Electrochemical Society, 126(12), p.2258.
2. Wen, C. J., Ho, C., Boukamp, B. A., Raistrick, I. D., Weppner, W., & Huggins, R. A. (1981). Use of electrochemical methods to determine chemical-diffusion coefficients in alloys: application to ‘LiAI’. International Metals Reviews, 26(1), 253-268.