title: A rechargeable room-temperature sodium superoxide (NaO2) battery.
abstract: In the search for room-temperature batteries with high energy densities, rechargeable metal-air (more precisely metal-oxygen) batteries are considered as particularly attractive owing to the simplicity of the underlying cell reaction at first glance. Atmospheric oxygen is used to form oxides during discharging, which-ideally-decompose reversibly during charging. Much work has been focused on aprotic Li-O(2) cells (mostly with carbonate-based electrolytes and Li(2)O(2) as a potential discharge product), where large overpotentials are observed and a complex cell chemistry is found. In fact, recent studies evidence that Li-O(2) cells suffer from irreversible electrolyte decomposition during cycling. Here we report on a Na-O(2) cell reversibly discharging/charging at very low overpotentials (< 200 mV) and current densities as high as 0.2 mA cm(-2) using a pure carbon cathode without an added catalyst. Crystalline sodium superoxide (NaO(2)) forms in a one-electron transfer step as a solid discharge product. This work demonstrates that substitution of lithium by sodium may offer an unexpected route towards rechargeable metal-air batteries.
authors.affiliation: Physikalisch-Chemisches Institut, Justus-Liebig-Universität Gießen, Gießen, Germany.
authors.forename: Pascal
authors.initials: P
authors.lastname: Hartmann
authors.forename: Conrad L
authors.initials: CL
authors.lastname: Bender
authors.forename: Miloš
authors.initials: M
authors.lastname: Vračar
authors.forename: Anna Katharina
authors.initials: AK
authors.lastname: Dürr
authors.forename: Arnd
authors.initials: A
authors.lastname: Garsuch
authors.forename: Jürgen
authors.initials: J
authors.lastname: Janek
authors.forename: Philipp
authors.initials: P
authors.lastname: Adelhelm