This project was funded by Fundamental Research Grant Scheme (FRGS).

Summary of project proposal:

High power rechargeable Li-ion battery with long cycle life is one of the most promising candidates to power batteryelectric vehicles. Usually high power state needs high rate operation which produces significant diffusion-induced stress, and thus leads to mechanical degradation associated with a limited cyclic life. Electrode microstructural engineering has been found to be a promising way for reducing mechanical degradation and improving cyclability.

However, to-date no quantitative models have been devised for elucidating the influences of the electrode microstructure and electrochemical reaction on the diffusion-induced stress and, hence, the mechanical degradation upon cyclic intercalation. Thus, the main objective of the proposed project is to achieve a better understanding of the

influence of electrode microstructure and different charging /discharging operations on the stress-coupled intercalation dynamics through computational modeling and simulation study and, hence, exploring the approaches for withstanding the stress in different nanostructured electrodes. In the proposed project, a thermodynamically consistent phase field model is adopted to study the interplay among stress generation, Li-ion concentration evolution and electrode microstructure.

A systematic computational modeling and simulation study will be carried out to ascertain the approaches for withstanding the stress in different electrode microstructures, and to determine the optimal electrode microstructure that can support high rate operation with superior cyclic life. Some layered nanocomposite electrode thin films will be fabricated and characterized to provide experimental data for validating the results obtained from the established theoretical model and numerical simulation.

Upon successful completion of the proposed project, the following achievements would have been made:

  1. Establishment of a phase field modeling framework to systematically investigate the effect of electrode microstructure on stress bearing.
  2. Determination of optimized electrode microstructures for improving the cyclability of nanostructured electrodes.

Charging and discharging of Li-ion battery