title: Visualizing non-equilibrium lithiation of spinel oxide via in situ transmission electron microscopy.
abstract: Spinel transition metal oxides are important electrode materials for lithium-ion batteries, whose lithiation undergoes a two-step reaction, whereby intercalation and conversion occur in a sequential manner. These two reactions are known to have distinct reaction dynamics, but it is unclear how their kinetics affects the overall electrochemical response. Here we explore the lithiation of nanosized magnetite by employing a strain-sensitive, bright-field scanning transmission electron microscopy approach. This method allows direct, real-time, high-resolution visualization of how lithiation proceeds along specific reaction pathways. We find that the initial intercalation process follows a two-phase reaction sequence, whereas further lithiation leads to the coexistence of three distinct phases within single nanoparticles, which has not been previously reported to the best of our knowledge. We use phase-field theory to model and describe these non-equilibrium reaction pathways, and to directly correlate the observed phase evolution with the battery's discharge performance.
authors.affiliation: Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Kai
authors.identifier: 0000-0003-4666-1800
authors.initials: K
authors.lastname: He
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Sen
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Xiqian
authors.identifier: 0000-0001-8513-518X
authors.initials: X
authors.lastname: Yu
authors.affiliation: Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Qingping
authors.initials: Q
authors.lastname: Meng
authors.affiliation: Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Yizhou
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Enyuan
authors.initials: E
authors.lastname: Hu
authors.affiliation: Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Ke
authors.initials: K
authors.lastname: Sun
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Hongseok
authors.initials: H
authors.lastname: Yun
authors.affiliation: Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Xiao-Qing
authors.initials: XQ
authors.lastname: Yang
authors.affiliation: Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Yimei
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Gan
authors.affiliation: Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Yifei
authors.identifier: 0000-0002-8162-4629
authors.initials: Y
authors.lastname: Mo
authors.affiliation: Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Eric A
authors.identifier: 0000-0002-3366-2153
authors.initials: EA
authors.lastname: Stach
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Murray
authors.affiliation: Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Dong
authors.identifier: 0000-0002-1921-6683
authors.initials: D
authors.lastname: Su