title: Magnetism in lithium-oxygen discharge product.
abstract: Nonaqueous lithium-oxygen batteries have a much superior theoretical gravimetric energy density compared to conventional lithium-ion batteries, and thus could render long-range electric vehicles a reality. A molecular-level understanding of the reversible formation of lithium peroxide in these batteries, the properties of major/minor discharge products, and the stability of the nonaqueous electrolytes is required to achieve successful lithium-oxygen batteries. We demonstrate that the major discharge product formed in the lithium-oxygen cell, lithium peroxide, exhibits a magnetic moment. These results are based on dc-magnetization measurements and a lithium-oxygen cell containing an ether-based electrolyte. The results are unexpected because bulk lithium peroxide has a significant band gap. Density functional calculations predict that superoxide-type surface oxygen groups with unpaired electrons exist on stoichiometric lithium peroxide crystalline surfaces and on nanoparticle surfaces; these computational results are consistent with the magnetic measurement of the discharged lithium peroxide product as well as EPR measurements on commercial lithium peroxide. The presence of superoxide-type surface oxygen groups with spin can play a role in the reversible formation and decomposition of lithium peroxide as well as the reversible formation and decomposition of electrolyte molecules.
authors.affiliation: Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.forename: Hun-Ji
authors.initials: HJ
authors.lastname: Jung
authors.forename: Kah Chun
authors.initials: KC
authors.lastname: Lau
authors.forename: Zhengcheng
authors.initials: Z
authors.lastname: Zhang
authors.forename: John A
authors.initials: JA
authors.lastname: Schlueter
authors.forename: Peng
authors.initials: P
authors.lastname: Du
authors.forename: Rajeev S
authors.initials: RS
authors.lastname: Assary
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Greeley
authors.forename: Glen A
authors.initials: GA
authors.lastname: Ferguson
authors.forename: Hsien-Hau
authors.initials: HH
authors.lastname: Wang
authors.forename: Jusef
authors.initials: J
authors.lastname: Hassoun
authors.forename: Hakim
authors.initials: H
authors.lastname: Iddir
authors.forename: Jigang
authors.initials: J
authors.lastname: Zhou
authors.forename: Lucia
authors.initials: L
authors.lastname: Zuin
authors.forename: Yongfeng
authors.initials: Y
authors.lastname: Hu
authors.forename: Yang-Kook
authors.initials: YK
authors.lastname: Sun
authors.forename: Bruno
authors.initials: B
authors.lastname: Scrosati
authors.forename: Larry A
authors.initials: LA
authors.lastname: Curtiss
authors.forename: Kahlil
authors.initials: K
authors.lastname: Amine
mesh_terms: D004553:Electric Conductivity; D011211:Electric Power Supplies; D008094:Lithium / Q000737:chemistry*; D060328:Magnetic Phenomena; D008958:Models, Molecular; D008968:Molecular Conformation; D010100:Oxygen / Q000737:chemistry*; D010545:Peroxides / Q000737:chemistry; D011789:Quantum Theory; D013499:Surface Properties
chemical_list: D010545:Peroxides; D008094:Lithium; D010100:Oxygen
keywords: batteries; density functional calculations; lithium peroxide; magnetic properties; superoxide