title: Reduction of charge and discharge polarization by cobalt nanoparticles-embedded carbon nanofibers for Li-O2 batteries.
abstract: The problem of high charge polarization is one of the most significant challenges in current nonaqueous Li-O2 batteries. The development of an electrode for the oxygen evolution reaction (OER) at reduced overpotential is thus essential. Here, we suggest a binder-free electrode based on Co nanoparticles embedded in carbon nanofibers (Co-CNFs), which simultaneously reduces the charge and discharge polarization and extends cycling stability. Co-CNF gives rise to a lower discharge polarization because of an enhanced oxygen reduction reaction activity compared to Co-free CNF. Although the embedment of Co does not enhance the OER activity, it significantly reduces charge overvoltage by forming easily decomposable amorphous Li2 O2 . A mechanism for the formation of amorphous Li2 O2 is suggested in terms of charge localization induced by the Co NPs. The findings suggest a new electrode design strategy of combining inexpensive metals and carbon materials for modulating the phase of the discharge product.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Republic of Korea).
authors.forename: Yun-Jung
authors.initials: YJ
authors.lastname: Kim
authors.affiliation: Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Republic of Korea).
authors.forename: Hongkyung
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Republic of Korea).
authors.forename: Dong Jin
authors.initials: DJ
authors.lastname: Lee
authors.affiliation: Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Republic of Korea). jungpark@kaist.ac.kr.
authors.forename: Jung-Ki
authors.initials: JK
authors.lastname: Park
authors.affiliation: Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Republic of Korea). heetak.kim@kaist.ac.kr.
authors.forename: Hee-Tak
authors.initials: HT
authors.lastname: Kim
mesh_terms: D002244:Carbon / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D011211:Electric Power Supplies; D004566:Electrodes; D008094:Lithium / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D057139:Nanofibers / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry
chemical_list: D010087:Oxides; D003035:Cobalt; D002244:Carbon; D008094:Lithium
keywords: batteries; charge transfer; cobalt; lithium peroxide; overpotential