Stability of thin film insertion electrodes
Stability of thin film insertion electrodes
This work investigated the effect of inserting and extracting lithium from metal oxides used in an electrochromic device. Both the electrochromic (tungsten oxide) electrode and the vanadium-titanium oxide electrode were studied separately. The electrochemical behaviour of these electrodes was studied using slow scan cyclic voltammetry and AC-impedance spectroscopy. Scanning electron microscopy was used to study the surface of the electrode before and after cycling. Vanadium-titanium oxide samples were also studied using electrochemical quartz crystal microbalance.
Two forms of tungsten oxide were studied: amorphous and crystalline tungsten oxide samples. Normal conditions for the electrochemical study of tungsten oxide electrodes were defined by a potential range of 2 V vs. Li/Li+ to 4.5 V vs. Li/Li+. The samples were then cycled to potentials as low as 1.6 V vs. Li/Li+. The amorphous samples showed a very poor stability at these potentials where crystalline samples showed a good stability. A model was proposed where the adhesion between the oxide layer and the underlying conductive layer is a key factor. Inserting lithium at very low potential causes an expansion of the film. When the strain forces exceed the adhesion forces, the expansion of the film causes film detachment. By heating the samples to get the crystalline form of tungsten oxide, the adhesion properties of the film and thus its stability upon lithium insertion-extraction are improved.
The electrochemical behaviour of tungsten oxide was studied using slow scan cyclic voltammetry, which showed a parasitic reaction superimposed on the insertion/extraction current. The quartz crystal microbalance in-situ measurements showed that hydrated lithium is inserted under mild conditions (above 3.2 v vs. Li/Li+).
University of Southampton
Gavanier, Béatrice
00deb33d-be28-47da-96c8-00bb80358139
2000
Gavanier, Béatrice
00deb33d-be28-47da-96c8-00bb80358139
Gavanier, Béatrice
(2000)
Stability of thin film insertion electrodes.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This work investigated the effect of inserting and extracting lithium from metal oxides used in an electrochromic device. Both the electrochromic (tungsten oxide) electrode and the vanadium-titanium oxide electrode were studied separately. The electrochemical behaviour of these electrodes was studied using slow scan cyclic voltammetry and AC-impedance spectroscopy. Scanning electron microscopy was used to study the surface of the electrode before and after cycling. Vanadium-titanium oxide samples were also studied using electrochemical quartz crystal microbalance.
Two forms of tungsten oxide were studied: amorphous and crystalline tungsten oxide samples. Normal conditions for the electrochemical study of tungsten oxide electrodes were defined by a potential range of 2 V vs. Li/Li+ to 4.5 V vs. Li/Li+. The samples were then cycled to potentials as low as 1.6 V vs. Li/Li+. The amorphous samples showed a very poor stability at these potentials where crystalline samples showed a good stability. A model was proposed where the adhesion between the oxide layer and the underlying conductive layer is a key factor. Inserting lithium at very low potential causes an expansion of the film. When the strain forces exceed the adhesion forces, the expansion of the film causes film detachment. By heating the samples to get the crystalline form of tungsten oxide, the adhesion properties of the film and thus its stability upon lithium insertion-extraction are improved.
The electrochemical behaviour of tungsten oxide was studied using slow scan cyclic voltammetry, which showed a parasitic reaction superimposed on the insertion/extraction current. The quartz crystal microbalance in-situ measurements showed that hydrated lithium is inserted under mild conditions (above 3.2 v vs. Li/Li+).
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Published date: 2000
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Local EPrints ID: 464114
URI: http://eprints.soton.ac.uk/id/eprint/464114
PURE UUID: 4b551ecf-6536-47e1-a3ec-7c6fc9ff2895
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Date deposited: 04 Jul 2022 21:18
Last modified: 16 Mar 2024 19:14
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Author:
Béatrice Gavanier
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