title: Rapid Mapping of Lithiation Dynamics in Transition Metal Oxide Particles with Operando X-ray Absorption Spectroscopy.
abstract: Since the commercialization of lithium ion batteries (LIBs), layered transition metal oxides (LiMO2, where M = Co, Mn, Ni, or mixtures thereof) have been materials of choice for LIB cathodes. During cycling, the transition metals change their oxidation states, an effect that can be tracked by detecting energy shifts in the X-ray absorption near edge structure (XANES) spectrum. X-ray absorption spectroscopy (XAS) can therefore be used to visualize and quantify lithiation kinetics in transition metal oxide cathodes; however, in-situ measurements are often constrained by temporal resolution and X-ray dose, necessitating compromises in the electrochemistry cycling conditions used or the materials examined. We report a combined approach to reduce measurement time and X-ray exposure for operando XAS studies of lithium ion batteries. A highly discretized energy resolution coupled with advanced post-processing enables rapid yet reliable identification of the oxidation state. A full-field microscopy setup provides sub-particle resolution over a large area of battery electrode, enabling the oxidation state within many transition metal oxide particles to be tracked simultaneously. Here, we apply this approach to gain insights into the lithiation kinetics of a commercial, mixed-metal oxide cathode material, nickel cobalt aluminium oxide (NCA), during (dis)charge and its degradation during overcharge.
authors.affiliation: Laboratory for Nanoelectronics, ETH Zürich, Zürich Switzerland.
authors.forename: Lea
authors.initials: L
authors.lastname: Nowack
authors.affiliation: microXAS, Paul Scherrer Institute, Villigen Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Grolimund
authors.affiliation: microXAS, Paul Scherrer Institute, Villigen Switzerland.
authors.forename: Vallerie
authors.initials: V
authors.lastname: Samson
authors.affiliation: TOMCAT, Paul Scherrer Institute, Villigen Switzerland.
authors.forename: Federica
authors.initials: F
authors.lastname: Marone
authors.affiliation: Laboratory for Nanoelectronics, ETH Zürich, Zürich Switzerland.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Wood