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Effective Electronic and Ionic Conductivities of Dense EV-Designed NMC-Based Positive Electrodes using Fourier Based Numerical Simulations on FIB/SEM Volumes
Abstract : Experimental conductivity measurements, obtained on NMC 532 -based electrodes with markedly different porosities and made with percolating and non-percolating CB/PVdF phase, are compared with full-field numerical predictions. These ones are based on segmented nanotomography images and phase bulk properties and contain no tunable parameter. A good agreement between the calculated and measured transport properties is observed. 3D current density fields give insights on the microstructure impacts on the current density distribution. Ionic transport is dominated by low tortuosity micrometric channels. Results also highlight the presence of “dead areas” in porosity that are crossed by a very low ionic current showing that, at high rate, the effective porosity may reduce to the micrometric pore network. For electronic conductivity, the CB/PVdF mixture percolation threshold is evaluated at 6%–7% in volume. Even below this key value threshold, CB/PVdF aggregates significantly improve electronic conductivity by forming gateways between NMC clusters thus minimising the constriction resistances between them. The size of the representative volume element relative to electronic and ionic conductivities is also investigated.
https://hal.archives-ouvertes.fr/hal-03011766
Contributor : Richard Baschera Connect in order to contact the contributor
Submitted on : Tuesday, January 12, 2021 - 11:19:50 AM
Last modification on : Monday, May 2, 2022 - 4:34:08 PM
Long-term archiving on: : Tuesday, April 13, 2021 - 6:21:37 PM
Contributor : Richard Baschera Connect in order to contact the contributor
Submitted on : Tuesday, January 12, 2021 - 11:19:50 AM
Last modification on : Monday, May 2, 2022 - 4:34:08 PM
Long-term archiving on: : Tuesday, April 13, 2021 - 6:21:37 PM
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