title: Interfacial effects on lithium superoxide disproportionation in Li-O₂ batteries.
abstract: During the cycling of Li-O2 batteries the discharge process gives rise to dynamically evolving agglomerates composed of lithium-oxygen nanostructures; however, little is known about their composition. In this paper, we present results for a Li-O2 battery based on an activated carbon cathode that indicate interfacial effects can suppress disproportionation of a LiO2 component in the discharge product. High-intensity X-ray diffraction and transmission electron microscopy measurements are first used to show that there is a LiO2 component along with Li2O2 in the discharge product. The stability of the discharge product was then probed by investigating the dependence of the charge potential and Raman intensity of the superoxide peak with time. The results indicate that the LiO2 component can be stable for possibly up to days when an electrolyte is left on the surface of the discharged cathode. Density functional calculations on amorphous LiO2 reveal that the disproportionation process will be slower at an electrolyte/LiO2 interface compared to a vacuum/LiO2 interface. The combined experimental and theoretical results provide new insight into how interfacial effects can stabilize LiO2 and suggest that these interfacial effects may play an important role in the charge and discharge chemistries of a Li-O2 battery.
authors.affiliation: Chemical Sciences and Engineering Division, ‡Materials Science Division, and §Electron Microscopy Center, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors.forename: Dengyun
authors.initials: D
authors.lastname: Zhai
authors.forename: Kah Chun
authors.initials: KC
authors.lastname: Lau
authors.forename: Hsien-Hau
authors.initials: HH
authors.lastname: Wang
authors.forename: Jianguo
authors.initials: J
authors.lastname: Wen
authors.forename: Dean J
authors.initials: DJ
authors.lastname: Miller
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.forename: Feiyu
authors.initials: F
authors.lastname: Kang
authors.forename: Baohua
authors.initials: B
authors.lastname: Li
authors.forename: Wenge
authors.initials: W
authors.lastname: Yang
authors.forename: Jing
authors.initials: J
authors.lastname: Gao
authors.forename: Ernesto
authors.initials: E
authors.lastname: Indacochea
authors.forename: Larry A
authors.initials: LA
authors.lastname: Curtiss
authors.forename: Khalil
authors.initials: K
authors.lastname: Amine
keywords: Lithium−oxygen battery; interface; lithium superoxide; nanostructure; stability