Spatial extent of lithium intercalation in anatase TiO{sub 2}
- Delft Univ. of Technology (Netherlands). Lab. for Inorganic Chemistry
Thin smooth anatase TiO{sub 2} films are obtained by electron beam evaporation of reduced TiO{sub 2}. These films show a preferential (004) orientation when deposited on electron beam evaporated amorphous titanium. Electrochemical lithium insertion into these films is studied with several optical and electrochemical techniques. A coloration efficiency of 13 cm{sup 2} C{sup {minus}1} is found, which is twice as high as that reported for TiO{sub 2} films grown by chemical vapor deposition (CVD). Potential-dependent capacitance measurements show that after the extraction of lithium ions has taken place a small region at the surface of the electrode has a much higher dielectric constant than that of the bulk of the electrode. This is explained by the presence of irreversibly trapped lithium ions in the region where a (reversible) phase transformation from anatase TiO{sub 2} to anatase Li{sub 0.5}TiO{sub 2} has occurred. The extent of this region depends strongly on the intercalation potential; values of 7 and 17 nm are found after 2.5 h of intercalation at {minus}1.0 and {minus}1.2 V vs SCE, respectively. The dielectric constant of the modified surface region is found to range between 500 and 900. A scheme is proposed that describes the mechanism of lithium insertion in terms of a moving TiO{sub 2}{vert_bar}Li{sub 0.5}TiO{sub 2} phase front.
- OSTI ID:
- 696647
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Journal Name: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical Journal Issue: 34 Vol. 103; ISSN 1089-5647; ISSN JPCBFK
- Country of Publication:
- United States
- Language:
- English
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