Numerical simulations of all-solid-state batteries using specific contact area diameters for active materials determined by X-ray computed tomography

Editors’ Choice—Visualizing the Impact of the Composite Cathode Microstructure and Porosity on Solid-State Battery Performance

“…This observation can be explained by smaller CAM clusters. Voids between individual CAM particles can be filled by the smaller sized ISE during fabrication 48 as already observed in the measured total porosity. This penetration of pore space between CAM particles goes hand in hand with shorter diffusion lengths for lithium ions and better kinetics.…”

“…This indicates improved ionic transport through the cathode and likely results from more and shorter ionic transport pathways and, thus, better percolation. The loss of el,eff σ may be explained by reduced clustering of active material particles and therefore a better overall distribution, as discussed by Iwamoto et al 48 CAM particle clusters serve as electronic "highways" with low R , el but they do not necessarily lead to lower overall cell resistance in full cells since particles inside the cluster have low contact areas to the ISE phase, which hinders charge transfer and blocks ionic transport on a micrometer scale, which is evident from the measured ion,eff σ values. Similar phenomenological observations were already made by several groups for other thiophosphate-based ISEs.…”

“…As there is yet no quantitative model for these effects, this needs further investigation. 42,48 ISE particle size determines cathode homogeneity and porosity.-As we intend to evaluate how particle clusters and the microstructure influences the kinetics of composite electrodes, we employed Xe-plasma FIB-SEM (PFIB-SEM) to measure the threedimensional microstructure of the three composite cathodes to a cubic voxel size of 100 nm. The images obtained from PFIB-SEM tomography were segmented into CAM, ISE and pore phases, based on gray scale values of both secondary electron (SE) and backscattered electron (BSE) images (Fig.…”

“…47 Iwamoto et al used nano-CT to obtain cathode reconstructions and simulated charge transport parameters for three different ISE particle sizes (75Li 2 S-25P 2 S 5 glass). 48 They found that clustering of active material particles, which is one of the mechanisms that limits SSB performance, can be reduced by smaller ISE particles. However, due to the nature of the employed technique, they could not determine and consider porosity in their reconstructions.…”

“…X-ray computed tomography (CT) and focused ion beam scanning electron microscopy (FIB-SEM). First studies have already reported such microstructures [45][46][47][48][49][50] and delivered valuable input for modelling groups that can use these reconstructions to simulate charge transport and battery operation on real models. For instance, chemo-mechanical failure of composite cathodes was investigated 51,52 and globally obtained data such as the charge transfer resistance of a cathode were z E-mail: philip.minnmann@phys.chemie.uni-giessen.de; johannes.schubert@phys.…”