Transport-Geometry Interactions in Li-Ion Cathode Materials Imaged Using X-ray Nanotomography

Abstract

Forging a stronger connection between mesoscale geometry, performance, and processing techniques can realize practical approaches for controlling battery performance using mesoscale geometry. To this end, 3D X-ray imaging, microstructural characterization, and computational modeling have been applied to analyze the intercalation behavior of Li(Ni 1/3 Mn 1/3 Co 1/3 )O 2 (NMC) cathodes. Samples extracted from pristine cathodes were imaged using X-ray nanotomography. Active material particle geometry was characterized and compared for samples from four cathodes treated with distinct preparation steps. Significant size reduction was observed in calendered and ball milled samples, and distinct differences were observed in particle morphology. Tomographic data for a representative particle was applied in a numerical transport model to assess the effect of particle geometry on intercalation. This assessment proved critical in determining an appropriate estimate of particle size for defining dimensionless parameters that permit rapid estimation of intercalation time. Defining an effective particle radius based on a sphere of equivalent surface area to volume ratio was found to provide the most accurate estimate of intercalation time. Informed by this analysis, dimensionless parameters were used to assess intercalation behavior of the cathode materials. This assessment revealed a substantial change in rate capability connected to particle size reductions achieved in calendering and ball milling.

Propulsion Research and Academic Programs at the University of Alabama in Huntsville - 2018

“…The effect of microstructural geometry on electrode performance is also being analyzed through experimental studies 90 and the use of nanotomography data as computational domains in finite element simulations. 91,92 The process of integrating microstructural data with computational modeling is illustrated in Fig. 15.…”

“…Microstructural characterization provides particle geometric data. Meshing and subsequent computational modeling permits correlation of microstructure to performance 91.…”

Local Substrate Heterogeneity Influences Electrochemical Activity of TEM Grid-Supported Battery Particles

“…Toward this goal, single particle-level electrochemical methods have been applied to battery materials (Heubner et al, 2020 ). Single particle-level electrochemical measurements reveal underlying ion and electron transport processes that are fundamentally related to solid state chemistry and the solid/electrolyte interface (Nelson et al, 2017 ; Wolf et al, 2017 ; Li et al, 2018 ; Yu et al, 2018 ). Scanning probe electrochemical methods have been used to uncover heterogeneous electrochemical activity of LiFePO 4 and LiMn 2 O 4 battery particles (Kumatani et al, 2014 ; Tao et al, 2019 ).…”

“…On the other hand, several atomic-level imaging methods have been used to study ion insertion kinetics of nanoparticle film or slurry electrodes (De Marco and Veder, 2010 ; Harks et al, 2015 ; Grey and Tarascon, 2017 ; Yuan et al, 2017 ; Tripathi et al, 2018 ; Boebinger et al, 2020 ; Li et al, 2020 ). Transmission electron microscopy (TEM; Huang et al, 2010 ; Liu and Huang, 2011 ; Liu et al, 2012 ; Zeng et al, 2014 , 2020 ; Qi et al, 2016 ; Xie et al, 2017 ) and X-ray (Totir et al, 1997 ; Ota et al, 2003 ; Deb et al, 2004 ; Kim and Chung, 2004 ; Chao et al, 2010 ; Shearing et al, 2011 ; Nelson et al, 2012 , 2017 ; Li et al, 2014 , 2018 ; Shapiro et al, 2014 ; Wolf et al, 2017 ; Yau et al, 2017 ; Yu et al, 2018 ) imaging methods have measured the real-time lithiation kinetics of nanoparticle electrodes and have successfully incorporated material properties such as film porosity, particle shape, orientation, and composition to predict the system's electrochemical response (Garcia et al, 2005 ; Gupta et al, 2011 ; Stephenson et al, 2011 ; Ebner et al, 2014 ; Landesfeind et al, 2018 ). In situ single particle-level TEM measurements have revealed dynamic structural information of battery materials (Huang et al, 2010 ).…”

Electrode Mesoscale as a Collection of Particles: Coupled Electrochemical and Mechanical Analysis of NMC

“…However, homogenized electrode properties can be difficult to experimentally measure and can vary widely based on material formulation, manufacturing conditions, state of charge, age, and other factors. Additionally, models intended to predict this behavior, such as the oft-used Bruggeman approximation [16], can be highly inaccurate at battery-relevant conditions [17][18][19][20][21][22]. Therefore, high-resolution, mesoscale resolved simulations can provide valuable insight into how the coupled electrochemical and mechanical phenomena that occur at the micro-and mesoscales impact macroscale performance.…”