Method to determine the in-plane tortuosity of porous electrodes

The tortuosity of a porous electrode is one of the critical parameters that governs the effective transport properties such as effective conductivity and effective diffusivity of ions in the electrolyte phase. While there exist several methods to determine the through-plane tortuosity for lithium-ion battery electrodes, methods to determine in-plane tortuosity are scarcely explored. In this paper, we present a method that restricts ion transport to only the in-plane direction, which facilitates the determination of transport properties in the in-plane direction. The here proposed cell design is analyzed using a blocking condition transmission line model to measure the in-plane tortuosity, followed by validation experiments to establish its validity and robustness. The measurement of the in-plane tortuosity may act as an indispensable tool for the design, characterization, and modeling of 3-dimensional battery architectures (e.g., laser structured electrodes) and help to estimate the distribution of various properties in the through-plane direction such as porosity, tortuosity, binder content, etc.