Nanobelts of Beta-Sodium Vanadate as Electrode for Magnesium and Dual Magnesium-Sodium Batteries

Nanoparticles of sodium vanadate (composition approximately NaV6O15) with nanobelt morphology and monoclinic structure (beta-phase) were prepared by using the hydrothermal method, alpha-V2O5 as vanadium source and sodium dodecyl sulfate as both surfactant and source of sodium. This material can reversibly accommodate lithium, sodium and magnesium in its framework. Sodium vanadate nanobelts exhibit lower capacity than V2O5 in lithium and sodium cell. In sodium cell, the electrochemical performance with NaOTf-diglyme electrolyte solution was much better than with NaClO4-propylene carbonate solution. In the case of dual sodium-magnesium electrolyte, the presence of sodium in beta-NaV6O15 and the small particle size improve the electrochemical behavior and increase the capacity (125 mAh g(-1)) in comparison with alpha-V2O5 (10 mAh g(-1)). The electrolyte solution based on Mg(BH4)(2) and NaBH4 dissolved in diglyme is compatible with Mg metal and yields to better electrochemical performance than magnesium perchlorate dissolved in acetonitrile. Both sodium and magnesium are reversibly intercalated at the positive electrode and electrodeposited at the negative electrode and, consequently, it can be described as a dual battery. On the other hand, a veritable magnesium-ion battery was made using MgMn2O4 as positive electrode and NaV6O15 as negative electrode, although the resulting operation voltage is low. (C) The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. All rights reserved.