File(s) under permanent embargo

Controlling the three-phase boundary in Na–Oxygen batteries: the synergy of carbon nanofibers and ionic liquid

journal contribution
posted on 01.09.2019, 00:00 authored by Cristina Pozo-GonzaloCristina Pozo-Gonzalo, Yafei Zhang, N Ortiz-Vitoriano, Jian Fang, M Enterría, M Echeverría, J M López del Amo, T Rojo, D R MacFarlane, Maria ForsythMaria Forsyth, Patrick HowlettPatrick Howlett
© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim A series of electrospun binder-free carbon nanofiber (CNF) mats have been studied as air cathodes for Na–oxygen batteries using a pyrrolidinium-based electrolyte and compared with the commercial air cathode Toray 090. A tenfold increase in the discharge capacity is attained when using CNFs in comparison with Toray 090, affording a discharge capacity of 1.53 mAh cm−2 at a high discharge rate of 0.63 mA cm−2. The good specific discharge and charge capacities of these CNFs are determined by the void space and the highly accessible surface of the carbon fiber. Furthermore, a threefold increase has been attained in terms of specific capacity by controlling the flooding of the air cathode and hence the location of the three-phase boundary within the CNF mat. The enhancement in performance has been correlated to the morphology, composition, distribution, and location of the discharge products. Sodium superoxide and peroxide were identified as the discharge products and, more importantly, the common side reaction discharge products, which are known to be detrimental to battery performance (including sodium fluoride, sodium hydroxide, and formate), were not observed, exemplifying the stability of the pyrrolidinium-based electrolyte and these binder-free CNF air cathodes.

History

Journal

ChemSusChem

Volume

12

Issue

17

Pagination

4054 - 4063

Publisher

Wiley

Location

London, Eng.

ISSN

1864-5631

eISSN

1864-564X

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2019, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim