title: Oxygen reduction by lithiated graphene and graphene-based materials.
abstract: Oxygen reduction reaction (ORR) plays a key role in lithium-air batteries (LABs) that attract great attention thanks to their high theoretical specific energy several times exceeding that of lithium-ion batteries. Because of their high surface area, high electric conductivity, and low specific weight, various carbons are often materials of choice for applications as the LAB cathode. Unfortunately, the possibility of practical application of such batteries is still under question as the sustainable operation of LABs with carbon cathodes is not demonstrated yet and the cyclability is quite poor, which is usually associated with oxygen reduced species side reactions. However, the mechanisms of carbon reactivity toward these species are still unclear. Here, we report a direct in situ X-ray photoelectron spectroscopy study of oxygen reduction by lithiated graphene and graphene-based materials. Although lithium peroxide (Li2O2) and lithium oxide (Li2O) reactions with carbon are thermodynamically favorable, neither of them was found to react even at elevated temperatures. As lithium superoxide is not stable at room temperature, potassium superoxide (KO2) prepared in situ was used instead to test the reactivity of graphene with superoxide species. In contrast to Li2O2 and Li2O, KO2 was demonstrated to be strongly reactive.
authors.affiliation: Moscow State University , 119991 Moscow, Russia.
authors.forename: Elmar Yu
authors.initials: EY
authors.lastname: Kataev
authors.forename: Daniil M
authors.initials: DM
authors.lastname: Itkis
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Fedorov
authors.forename: Boris V
authors.initials: BV
authors.lastname: Senkovsky
authors.forename: Dmitry Yu
authors.initials: DY
authors.lastname: Usachov
authors.forename: Nikolay I
authors.initials: NI
authors.lastname: Verbitskiy
authors.forename: Alexander
authors.initials: A
authors.lastname: Grüneis
authors.forename: Alexei
authors.initials: A
authors.lastname: Barinov
authors.forename: Daria Yu
authors.initials: DY
authors.lastname: Tsukanova
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Volykhov
authors.forename: Kirill V
authors.initials: KV
authors.lastname: Mironovich
authors.forename: Victor A
authors.initials: VA
authors.lastname: Krivchenko
authors.forename: Maksim G
authors.initials: MG
authors.lastname: Rybin
authors.forename: Elena D
authors.initials: ED
authors.lastname: Obraztsova
authors.forename: Clemens
authors.initials: C
authors.lastname: Laubschat
authors.forename: Denis V
authors.initials: DV
authors.lastname: Vyalikh
authors.forename: Lada V
authors.initials: LV
authors.lastname: Yashina
keywords: carbon nanowalls; graphene; graphite intercalation compounds; lithium−air battery; oxygen reduction reaction