Quantifying Uncertainty in Tortuosity Estimates for Porous Electrodes

Measuring tortuosity in porous electrodes is important for understanding rate capability and optimizing design. Here, we describe an approach to determine electrode tortuosities and quantify the associated uncertainties by fitting a P2D model to discharge profiles from a standard rate capability test. A dimensionless current is identified as a design-of-experiment parameter that can be used to identify experiments that return confident estimates of tortuosity, even when other model parameters are not known with certainty. This approach is applied to analysis of LixV(3)O(8) (LVO) electrodes and LixNi0.33Mn0.33Co0.33O2 (NMC) electrodes. The details of the assumptions made in these measurements and their impact on the reported uncertainties are discussed. We also perform an uncertainty analysis on the standard method for quantifying tortuosity in the literature: electrochemical impedance spectroscopy collected under blocking electrolyte conditions. We find that confident estimates can be obtained using this approach even when uncertainties in equivalent circuit model parameters are considered. (C) 2021 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.

Automated summary

This study presents an approach to determine tortuosity in porous electrodes by fitting a P2D model to discharge profiles, identifying a dimensionless current as a key parameter for confident estimates of tortuosity. The method is applied to analyze LVO and NMC electrodes, discussing assumptions and uncertainties in the measurements. Additionally, an uncertainty analysis is conducted on the standard method of quantifying tortuosity using electrochemical impedance spectroscopy under blocking electrolyte conditions, showing confident estimates can be obtained despite uncertainties in equivalent circuit model parameters.