title: Achieving Low Overpotential Li-O₂ Battery Operations by Li₂O₂ Decomposition through One-Electron Processes.
abstract: As a promising high-capacity energy storage technology, Li-O2 batteries face two critical challenges, poor cycle lifetime and low round-trip efficiencies, both of which are connected to the high overpotentials. The problem is particularly acute during recharge, where the reactions typically follow two-electron mechanisms that are inherently slow. Here we present a strategy that can significantly reduce recharge overpotentials. Our approach seeks to promote Li2O2 decomposition by one-electron processes, and the key is to stabilize the important intermediate of superoxide species. With the introduction of a highly polarizing electrolyte, we observe that recharge processes are successfully switched from a two-electron pathway to a single-electron one. While a similar one-electron route has been reported for the discharge processes, it has rarely been described for recharge except for the initial stage due to the poor mobilities of surface bound superoxide ions (O2(-)), a necessary intermediate for the mechanism. Key to our observation is the solvation of O2(-) by an ionic liquid electrolyte (PYR14TFSI). Recharge overpotentials as low as 0.19 V at 100 mA/g(carbon) are measured.
authors.affiliation: Department of Chemistry, Merkert Chemistry Center, Boston College , 2609 Beacon Street, Chestnut Hill, Massachusetts 02467 United States.
authors.forename: Jin
authors.initials: J
authors.lastname: Xie
authors.affiliation: Department of Chemistry, Merkert Chemistry Center, Boston College , 2609 Beacon Street, Chestnut Hill, Massachusetts 02467 United States.
authors.forename: Qi
authors.initials: Q
authors.lastname: Dong
authors.affiliation: Department of Chemistry, Merkert Chemistry Center, Boston College , 2609 Beacon Street, Chestnut Hill, Massachusetts 02467 United States.
authors.forename: Ian
authors.initials: I
authors.lastname: Madden
authors.affiliation: Department of Chemistry, Merkert Chemistry Center, Boston College , 2609 Beacon Street, Chestnut Hill, Massachusetts 02467 United States.
authors.forename: Xiahui
authors.initials: X
authors.lastname: Yao
authors.affiliation: Department of Chemistry, Merkert Chemistry Center, Boston College , 2609 Beacon Street, Chestnut Hill, Massachusetts 02467 United States.
authors.forename: Qingmei
authors.initials: Q
authors.lastname: Cheng
authors.affiliation: Department of Chemical Engineering, University of Massachusetts , 686 North Pleasant Street, Amherst, Massachusetts 01003 United States.
authors.forename: Paul
authors.initials: P
authors.lastname: Dornath
authors.affiliation: Department of Chemical Engineering, University of Massachusetts , 686 North Pleasant Street, Amherst, Massachusetts 01003 United States.
authors.forename: Wei
authors.initials: W
authors.lastname: Fan
authors.affiliation: Department of Chemistry, Merkert Chemistry Center, Boston College , 2609 Beacon Street, Chestnut Hill, Massachusetts 02467 United States.
authors.forename: Dunwei
authors.initials: D
authors.lastname: Wang
keywords: Energy storage; Li−O2 battery; electrochemistry; ionic liquids; oxygen evolution reactions