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Ion Pairing Limits Crystal Growth in Metal-Oxygen Batteries

Aetukuri, Nagaphani B and Jones, Gavin O and Thompson, Leslie E and Ozgit-Akgun, Cagla and Akca, Esin and Demirci, Gokhan and Kim, Ho-Cheol and Bethune, Donald S and Virwani, Kumar and Wallraff, Gregory M (2018) Ion Pairing Limits Crystal Growth in Metal-Oxygen Batteries. In: ACS ENERGY LETTERS, 3 (10). pp. 2342-2348.

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Official URL: http://dx.doi.org/10.1021/acsenergylett.8b01387

Abstract

Aprotic alkali metal-oxygen batteries are promising high specific energy alternatives to Li-ion batteries. Growth and dissolution of alkali metal oxides such as Li2O2 in Li-O-2 batteries and NaO2 and KO2 in Na-O-2 and K-O-2 batteries, respectively, are central to the discharge and charge processes in these batteries. However, crystal growth and dissolution of the discharge products is poorly understood, especially in aprotic electrolytes. In this work, we chose the growth of NaO2 in Na-O-2 batteries as a model system and show a strong correlation between the electrolyte salt concentration and the NaO2 crystal size. With a combination of experiments and theory, we argue that the correlation is a direct manifestation of the strong cation-anion interactions, leading to decreased crystal growth rate at high salt concentrations. Furthermore, we propose and experimentally demonstrate that cation-coordinating crown molecules are electrochemically stable electrolyte additives that weaken ion pairing and enhance discharge capacities in metal-oxygen batteries.

Item Type: Journal Article
Additional Information: Copy right for this article belong to AMER CHEMICAL SOC
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Depositing User: Id for Latest eprints
Date Deposited: 15 Nov 2018 14:11
Last Modified: 18 Feb 2019 10:24
URI: http://eprints.iisc.ac.in/id/eprint/61066

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