Health & Environmental Research Online (HERO)


Print Feedback Export to File
7747660 
Journal Article 
Electrochemical intercalation of lithium into hexagonal tungsten trioxide 
Kumagai, N; Yu, AS; Kumagai, N; Yashiro, H 
1997 
1 
Thermochimica Acta
ISSN: 0040-6031
EISSN: 1872-762X 
Elsevier 
299 
1-2 
19-25 
English 
WOS:A1997XY79300005 
The kinetics and thermodynamics of electrochemical intercalation of lithium into hexagonal WO3 prepared by a solution technique were studied with an a.c. impedance method, open-circuit potential and X-ray diffraction measurements. The open-circuit potential-x in LixWO3 curve consists of two straight lines with different slopes, which was related to the structural variation in the oxide with lithium intercalation. The standard Gibbs energy of lithium intercalation, ΔG01, was -239.4 kj/mol in the range of x from 0 to 1 in LixWO3 at 25°C. The chemical diffusion coefficient of lithium, D̃, for the intercalation into the oxide, was measured by a.c. impedance method as functions of depth of lithium intercalation and temperature in 1 M LiClO4/propylene carbonate solution. The results showed that the Warburg impedance was linearly related to ω-1/2 (ω: angular frequency) and the (D̃) values obtained decreased with an increase in lithium concentration in the oxide, being one-two orders of magnitude higher than that in monoclinic WO3. Furthermore, the lithium diffusion coefficient of lithium and the activation energy for the diffusion were also obtained as a function of x-value in LixWO3. 
electrochemical lithium intercalation reaction; hexagonal tungsten trioxide; kinetics; thermodynamics