The electrode tortuosity factor: why the conventional tortuosity factor is not well suited for quantifying transport in porous Li-ion battery electrodes and what to use instead

Tuan-Tu Nguyen , Arnaud Demortière , Benoit Fleutot , Bruno Delobel , Charles Delacourt (1, 2) , Samuel J Cooper

1 RS2E - Réseau sur le stockage électrochimique de l'énergie
2 LRCS - Laboratoire réactivité et chimie des solides - UMR CNRS 7314

The tortuosity factor of porous battery electrodes is an important parameter used to correlate electrode microstructure with performance through numerical modeling. Therefore, having an appropriate method for the accurate determination of tortuosity factors is critical. This paper presents a numerical approach, based on simulations performed on numerically-generated microstructural images, which enables a comparison between two common experimental methods. Several key issues with the conventional "flow through" type tortuosity factor are highlighted, when used to characterise electrodes. As a result, a new concept called the "electrode tortuosity factor" is introduced, which captures the transport processes relevant to porous electrodes better than the "flow through" type tortuosity factor. The simulation results from this work demonstrate the importance of nonpercolating ("dead-end") pores in the performance of real electrodes. This is an important result for optimizing electrode design that should be considered by electrochemical modelers. This simulation tool is provided as an open-source MATLAB application and is freely available online as part of the TauFactor platform.

Domaines: Chimie analytique; Génie chimique; Matériaux

Tuan-Tu Nguyen, Arnaud Demortière, Benoit Fleutot, Bruno Delobel, Charles Delacourt, et al.. The electrode tortuosity factor: why the conventional tortuosity factor is not well suited for quantifying transport in porous Li-ion battery electrodes and what to use instead. npj Computational Materials, 2020, 6 (1), ⟨10.1038/s41524-020-00386-4⟩. ⟨hal-03095260⟩