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Published February 2016 | public
Journal Article

Three-Phase 3D Reconstruction of a LiCoO_2 Cathode via FIB-SEM Tomography

Abstract

Three-phase three-dimensional (3D) microstructural reconstructions of lithium-ion battery electrodes are critical input for 3D simulations of electrode lithiation/delithiation, which provide a detailed understanding of battery operation. In this report, 3D images of a LiCoO_2 electrode are achieved using focused ion beam-scanning electron microscopy (FIB-SEM), with clear contrast among the three phases: LiCoO_2 particles, carbonaceous phases (carbon and binder) and the electrolyte space. The good contrast was achieved by utilizing an improved FIB-SEM sample preparation method that combined infiltration of the electrolyte space with a low-viscosity silicone resin and triple ion-beam polishing. Morphological parameters quantified include phase volume fraction, surface area, feature size distribution, connectivity, and tortuosity. Electrolyte tortuosity was determined using two different geometric calculations that were in good agreement. The electrolyte tortuosity distribution versus position within the electrode was found to be highly inhomogeneous; this will lead to inhomogeneous electrode lithiation/delithiation at high C-rates that could potentially cause battery degradation.

Additional Information

© 2016 Microscopy Society of America. Received June 4, 2015; accepted December 1, 2015; Published online: 14 January 2016. The authors acknowledge financial support from the Office of Naval Research Grant #N00014-12-1-0713 and Northwestern University Cabell Terminal Year Fellowship. They thank Dr. James W. Fleming for providing the battery samples studied in this report. They also thank Dr. Noah Shanti and Sarah Miller for help with the tortuosity calculations via the PLR method. The triple-ion cutting was performed at the Optical Microscopy and Metallography Facility at the Materials Research Center of Northwestern University. FIBSEM (FEI) was performed in the EPIC facility of the NUANCE Center at Northwestern University. The NUANCE Center is supported by NSF-NSEC, NSF-MRSEC, Keck Foundation, the State of Illinois, and Northwestern University.

Additional details

Created:
August 22, 2023
Modified:
October 20, 2023