Modified Archimedes Method for the Measurement of Average Porosity of Lithium-Ion Battery Electrodes and Its Comparison with Standard Techniques

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Siva Dev, Rabin ; Mertin, Gerrit Karl ; Oldenburger, Marc ; Wycisk, Dominik ; Günther, Jonas ; Moos, Ralf ; Schmidt, Jan Philipp:
Modified Archimedes Method for the Measurement of Average Porosity of Lithium-Ion Battery Electrodes and Its Comparison with Standard Techniques.
In: Journal of the Electrochemical Society. (2026) .
ISSN 1945-7111
DOI: https://doi.org/10.1149/1945-7111/ae61f8

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Abstract

This work presents a simple method for obtaining highly reproducible and precise values of the average porosity of electrodes used in lithium-ion batteries. The method was developed by modifying the classical Archimedes method (hence referred to as the Modified Archimedes Method or MAM) and employs dimethyl carbonate (DMC) as the immersion liquid to closely mimic electrolyte infiltration. All aspects of the method, measurement setup design, experimental protocol, error propagation, and validation of results, were systematically assessed. The wetting properties of DMC and battery electrolytes were also compared and shown to be very similar. As a benchmark, electrode porosity was determined using four conventional methods: pycnometry, N2 adsorption, mercury intrusion porosimetry (MIP), and SEM imaging, and then compared with results from MAM. Closely aligning porosities were obtained between MAM, pycnometry and MIP. Subsequently, each method was evaluated on the basis of practical considerations, highlighting the advantages of MAM in terms of simplicity, speed and overall efficiency. Characterization of formed, aged, and charged electrodes are also possible using MAM after implementation inside a glove-box, the process of which is simple due to its compact design and minimal external requirements.