Geometric Characteristics of Three-Phase Porous Microstructures for All Solid-State Lithium Ion Batteries
By using synchrotron nano-computed tomography (nano-CT) at Argonne National Lab, we implemented quantitative study of the microstructures of all solid-state LIBs. The three-phase electrode was fabricated from a 47:47:6 (wt%) mixture of Li(Ni1/3 Mn1/3 Co1/3)O2 as active material (NMC), Li1.3Ti1.7Al0.3(PO4)3as Li-ion conductor (LTAP), and Super P carbon as electron conductor. The electrodes were packed under two different pressures (700 psi and 1300 psi) to control the volume fractions of void phase. To obtain the morphology data of the electrodes, TXM measurements were carried out adjusting energy levels of a synchrotron x-ray source. The x-ray generated images of solid-state electrodes with a 60 nm of spatial resolution at 8 keV are shown in Fig. 1. The gray-scaled intensity values of the images indicate the x-ray absorption rate of the materials. From the Fig. 1 (a) and (b), NMC particles, LTAP particles, and pores can be distinguished due to their different intensity values. Based on the reconstructed microstructure, the geometric characteristics will be presented to understand the lithium ion and electron pathways in all solid-state LIBs.
Acknowledgments: This work was supported by US National Science Foundation under Grant No. 1335850.
1. P. Knauth, Solid State Ionics, 180, 911 (2009).
2. N. M. Asl, J. Keith, C. Lim, L. Zhu, and Y. Kim, Electrochimica Acta, 79, 8 (2012).