title: 2D Cross Sectional Analysis and Associated Electrochemistry of Composite Electrodes Containing Dispersed Agglomerates of Nanocrystalline Magnetite, Fe₃O₄.
abstract: When electroactive nanomaterials are fully incorporated into an electrode structure, characterization of the crystallite sizes, agglomerate sizes, and dispersion of the electroactive materials can lend insight into the complex electrochemistry associated with composite electrodes. In this study, composite magnetite electrodes were sectioned using ultramicrotome techniques, which facilitated the direct observation of crystallites and agglomerates of magnetite (Fe3O4) as well as their dispersal patterns in large representative sections of electrode, via 2D cross sectional analysis by Transmission Electron Microscopy (TEM). Further, the electrochemistry of these electrodes were recorded, and Transmission X-ray Microscopy (TXM) was used to determine the distribution of oxidation states of the reduced magnetite. Unexpectedly, while two crystallite sizes of magnetite were employed in the production of the composite electrodes, the magnetite agglomerate sizes and degrees of dispersion in the two composite electrodes were similar to each other. This observation illustrates the necessity for careful characterization of composite electrodes, in order to understand the effects of crystallite size, agglomerate size, and level of dispersion on electrochemistry.
authors.affiliation: †Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States.
authors.forename: David C
authors.initials: DC
authors.lastname: Bock
authors.affiliation: ‡Brookhaven National Laboratory, Upton, New York 11973, United States.
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Kirshenbaum
authors.affiliation: ‡Brookhaven National Laboratory, Upton, New York 11973, United States.
authors.forename: Jiajun
authors.initials: J
authors.lastname: Wang
authors.affiliation: ‡Brookhaven National Laboratory, Upton, New York 11973, United States.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: ‡Brookhaven National Laboratory, Upton, New York 11973, United States.
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.affiliation: ‡Brookhaven National Laboratory, Upton, New York 11973, United States.
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.affiliation: †Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States.|§Department of Materials Science and Engineering, Stony Brook University, Stony Brook, New York 11794, United States.
authors.forename: Amy C
authors.initials: AC
authors.lastname: Marschilok
authors.affiliation: †Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States.|§Department of Materials Science and Engineering, Stony Brook University, Stony Brook, New York 11794, United States.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Takeuchi
authors.affiliation: †Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States.|‡Brookhaven National Laboratory, Upton, New York 11973, United States.|§Department of Materials Science and Engineering, Stony Brook University, Stony Brook, New York 11794, United States.
authors.forename: Esther S
authors.initials: ES
authors.lastname: Takeuchi
keywords: agglomerate; crystallite size; lithium-ion battery; magnetite; transmission X-ray microscopy; ultramicrotome