title: In situ determination of the liquid/solid interface thickness and composition for the Li ion cathode LiMn(1.5)Ni(0.5)O4.
abstract: Using neutron reflectometry, we have determined the thickness and scattering length density profile of the electrode-electrolyte interface for the high-voltage cathode LiMn(1.5)Ni(0.5)O4 in situ at open circuit voltage and fully delithiated. Upon exposure to a liquid electrolyte, a thin 3.3 nm Li-rich interface forms due to the ordering of the electrolyte on the cathode surface. This interface changes in composition, as evident by an increase in the scattering length density of the new layer, with charging as the condensed layer evolves from being lithium rich to one containing a much higher concentration of F from the LiPF6 salt. These results show the surface chemistry evolves as a function of the potential.
authors.affiliation: Chemical and Engineering Materials Division and ‡Materials Science and Technology Division, Oak Ridge National Laboratory , Oak Ridge Tennessee 37831, United States.
authors.forename: James F
authors.initials: JF
authors.lastname: Browning
authors.forename: Loïc
authors.initials: L
authors.lastname: Baggetto
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Jungjohann
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Wang
authors.forename: Wyatt E
authors.initials: WE
authors.lastname: Tenhaeff
authors.forename: Jong K
authors.initials: JK
authors.lastname: Keum
authors.forename: David L
authors.initials: DL
authors.lastname: Wood
authors.forename: Gabriel M
authors.initials: GM
authors.lastname: Veith
keywords: Li ion batteries; SEI layer; in situ battery; liquid−solid interface; neutron reflectometry