The impact of calendering process on the geometric characteristics and electrochemical performance of LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC) electrode was investigated in this study. The geometric properties of NMC electrodes with different calendering conditions, such as porosity, pore size distribution, particle size distribution, specific surface area and tortuosity were calculated from the computed tomography data of the electrodes. A synchrotron transmission X-ray microscopy tomography system at the Advanced Photon Source of the Argonne National Laboratory was employed to obtain the tomography data. The geometric and electrochemical analysis show that calendering can increase the electrochemically active area, which improves rate capability. However, more calendering will result in crushing of NMC particles, which can reduce the electrode capacity at relatively high C rates. This study shows that the optimum electrochemical performance of NMC electrode at 94:3:3 weight ratio of NMC:binder:carbon black can be achieved by calendering to 3.0 g/cm 3 NMC density.

To investigate geometric and electrochemical characteristics of Li ion battery electrode with different packing densities, lithium cobalt oxide (LiCoO 2 ) cathode electrodes were fabricated from a 94:3:3 (wt%) mixture of LiCoO 2 , polymeric binder, and super-P carbon black and calendered to different densities. A synchrotron X-ray nano-computed tomography system with a spatial resolution of 58.2 nm at the Advanced Photon Source of the Argonne National Laboratory was employed to obtain three dimensional morphology data of the electrodes. The morphology data were quantitatively analyzed to characterize their geometric properties, such as porosity, tortuosity, specific surface area, and pore size distribution. The geometric and electrochemical analysis reveal that high packing density electrodes have smaller average pore size and narrower pore size distribution, which improves the electrical contact between carbon-binder matrix and LiCoO 2 particles. The better contact improves the capacity and rate capability by reducing the possibility of electrically isolated LiCoO 2 particles and increasing the electrochemically active area. The results show that increase of packing density results in higher tortuosity, but electrochemically active area is more crucial to cell performance than tortuosity at up to 3.6 g/cm 3 packing density and 4 C rate.

A synchrotron transmission X-ray microscopy tomography system with a spatial resolution of 58.2 nm at the Advanced Photon Source was employed to obtain three-dimensional morphological data of all-solid Li-ion battery electrodes. The three-phase electrode was fabricated from a 47:47:6 (wt %) mixture of Li(NiMnCo)O as active material, LiTiAl(PO) as Li-ion conductor, and Super-P carbon as electron conductor. The geometric analysis show that particle-based all-solid Li-ion battery has serious contact interface problem which significantly impact the Li-ion transport and intercalation reaction in the electrode, leading to low capacity, poor rate capability and cycle life.