This report focuses on the effect of cell assembly and repeated cycling on tortuosity. Using a method previously developed by our group, namely the polarization-interrupt method , as well as AC impedance techniques, we were able to determine electrode tortuosity for various electrode films. There is clear evidence of changes in tortuosity during cell formation and cycling steps. These experiments also suggest that electrolyte wetting is a time-dependent process that changes the measured tortuosity.
Three different stages of electrodes were compared: (1) pristine electrodes which had never been in contact with electrolyte, (2) electrodes harvested from newly assembled batteries, and (3) electrodes harvested from cycled batteries. This was done for both anodes and cathodes. In the case of the harvested electrodes, a careful washing procedure is needed to remove Li salt. To validate our results we used two different experimental methods, namely the polarization-interrupt method and a blocking-electrolyte method recently discussed by Gasteiger and coworkers .
This research was funded by the BMR program of the US Department of Energy.