Title: Structure stability of Li_xH_yV₃O₈ exposed to water-vapour

Authors: Mário Simões; Lassi Karvonen; Alexandra Maegli; Songhak Yoon; Simone Pokrant; Anke Weidenkaff; Yoann Mettan

Addresses: Empa – Swiss Federal Laboratories for Materials Science and Technology Laboratory for Solid State Chemistry and Catalysis, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland ' Empa – Swiss Federal Laboratories for Materials Science and Technology Laboratory for Solid State Chemistry and Catalysis, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland ' Empa – Swiss Federal Laboratories for Materials Science and Technology Laboratory for Solid State Chemistry and Catalysis, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland ' Empa – Swiss Federal Laboratories for Materials Science and Technology Laboratory for Solid State Chemistry and Catalysis, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland ' Empa – Swiss Federal Laboratories for Materials Science and Technology Laboratory for Solid State Chemistry and Catalysis, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland ' Empa – Swiss Federal Laboratories for Materials Science and Technology Laboratory for Solid State Chemistry and Catalysis, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland ' Belenos Clean Power Holding Ltd., c/o EM Microelectronic Marin SA, Rue des Sors 3, CH-2074 Marin-Epagnier, Switzerland

Abstract: Chemically lithiated Li_xH_yV₃O₈ was prepared as the starting material in this study owing to its interesting properties for lithium-ion intercalation and further application in the positive electrode of lithium-ion batteries. The hydrophilic character of the synthesised compound was evaluated because even ppm water level inside batteries containing electrolytes with fluorinated salts like LiPF₆ can dramatically influence the battery stability. The structural stability of the lithiated vanadate after exposure to water-vapour was evaluated ex situ by XRD, TGA and TEM. TGA showed that at least 4 wt.% of water can be incorporated into the material. Water intercalates in the vanadate lattice filling the particles from the outer shell towards the bulk. Prolonged exposure to water-vapour saturated atmosphere leads to irreversible exfoliation of the crystal structure. Weakly bonded intercalated water can be removed without any damage to the crystal structure by an annealing step at 200°C for 2 h in air.

Keywords: lithium-ion batteries; LIBs; cathode; H2V3O8; vanadium oxide hydrate; high energy density; hydrophilic; intercalation; exfoliation; hydrothermal; water vapour; nanotechnology.

DOI: 10.1504/IJNT.2014.063800

International Journal of Nanotechnology, 2014 Vol.11 No.9/10/11, pp.932 - 945

Published online: 14 Jan 2015 *

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