title: Three-Phase 3D Reconstruction of a LiCoO2 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 LiCoO2 electrode are achieved using focused ion beam-scanning electron microscopy (FIB-SEM), with clear contrast among the three phases: LiCoO2 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.
authors.affiliation: 1Department of Materials Science and Engineering,Northwestern University,Evanston,IL 60208,USA.
authors.forename: Zhao
authors.identifier: http://orcid.org/0000-0003-0370-2406
authors.initials: Z
authors.lastname: Liu
authors.affiliation: 2Photon Science Directorate,Brookhaven National Laboratory,Upton,NY 11973,USA.
authors.forename: Yu-Chen K
authors.initials: YC
authors.lastname: Chen-Wiegart
authors.affiliation: 2Photon Science Directorate,Brookhaven National Laboratory,Upton,NY 11973,USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.affiliation: 1Department of Materials Science and Engineering,Northwestern University,Evanston,IL 60208,USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Barnett
authors.affiliation: 1Department of Materials Science and Engineering,Northwestern University,Evanston,IL 60208,USA.
authors.forename: Katherine T
authors.initials: KT
authors.lastname: Faber
keywords: FIB-SEM tomography; Li-ion batteries; cathode; microstructure; three-phase 3D reconstruction