Stochastic 3D reconstruction of cracked polycrystalline NMC particles using 2D SEM data

TL;DR

This paper introduces a stochastic method to reconstruct 3D cracked cathode particles from 2D SEM images, enabling better analysis of microstructure effects on battery performance without costly 3D imaging.

Contribution

A novel stereological approach that generates statistically equivalent 3D cracked particles from 2D data, facilitating microstructure analysis in battery research.

Findings

Successfully generates 3D crack networks from 2D images

Enables quantitative microstructure characterization without 3D imaging

Supports future electro-chemo-mechanical simulations

Abstract

Li-ion battery performance is strongly influenced by their cathodes' properties and consequently by the 3D microstructure of the particles the cathodes are comprised of. During calendaring and cycling, cracks develop within cathode particles, which may affect performance in multiple ways. On the one hand, cracks reduce internal connectivity such that electron transport within cathode particles is hindered. On the other hand, intra-particle cracks can increase the cathode reactive surface. Due to these contradictory effects, it is necessary to quantitatively investigate how battery cycling effects cracking and how cracking in-turn influences battery performance. Thus, it is necessary to characterize the 3D particle morphology with structural descriptors and quantitatively correlate them with effective battery properties. Typically, 3D structural characterization is performed using image data. However, informative 3D imaging techniques are time-consuming, costly and rarely available, such that analyses often have to rely on 2D image data. This paper presents a novel stereological approach for generating virtual 3D cathode particles that exhibit crack networks that are statistically equivalent to those observed in 2D sections of experimentally measured particles. Consequently, more easily available 2D image data suffices for deriving a full 3D characterization of cracked cathodes particles. In future research, the virtually generated 3D particles will be used as geometry input for spatially resolved electro-chemo-mechanical simulations, to enhance our understanding of structure-property relationships of cathodes in Li-ion batteries.