title: Tracking lithium transport and electrochemical reactions in nanoparticles.
abstract: Expectations for the next generation of lithium batteries include greater energy and power densities along with a substantial increase in both calendar and cycle life. Developing new materials to meet these goals requires a better understanding of how electrodes function by tracking physical and chemical changes of active components in a working electrode. Here we develop a new, simple in-situ electrochemical cell for the transmission electron microscope and use it to track lithium transport and conversion in FeF(2) nanoparticles by nanoscale imaging, diffraction and spectroscopy. In this system, lithium conversion is initiated at the surface, sweeping rapidly across the FeF(2) particles, followed by a gradual phase transformation in the bulk, resulting in 1-3 nm iron crystallites mixed with amorphous LiF. The real-time imaging reveals a surprisingly fast conversion process in individual particles (complete in a few minutes), with a morphological evolution resembling spinodal decomposition. This work provides new insights into the inter- and intra-particle lithium transport and kinetics of lithium conversion reactions, and may help to pave the way to develop high-energy conversion electrodes for lithium-ion batteries.
authors.affiliation: Brookhaven National Laboratory, Upton, New York 11973, USA. fwang@bnl.gov
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.forename: Hui-Chia
authors.initials: HC
authors.lastname: Yu
authors.forename: Min-Hua
authors.initials: MH
authors.lastname: Chen
authors.forename: Lijun
authors.initials: L
authors.lastname: Wu
authors.forename: Nathalie
authors.initials: N
authors.lastname: Pereira
authors.forename: Katsuyo
authors.initials: K
authors.lastname: Thornton
authors.forename: Anton
authors.initials: A
authors.lastname: Van der Ven
authors.forename: Yimei
authors.initials: Y
authors.lastname: Zhu
authors.forename: Glenn G
authors.initials: GG
authors.lastname: Amatucci
authors.forename: Jason
authors.initials: J
authors.lastname: Graetz