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Title: Electrochemical properties of carbon-coated CaWO4 versus Li
Authors: Sharma, N. 
Subba Rao, G.V. 
Chowdari, B.V.R. 
Keywords: CaWO4
Electrochemical properties
Li-ion batteries
Scheelite structure
Issue Date: 20-Sep-2005
Citation: Sharma, N., Subba Rao, G.V., Chowdari, B.V.R. (2005-09-20). Electrochemical properties of carbon-coated CaWO4 versus Li. Electrochimica Acta 50 (27) : 5305-5312. ScholarBank@NUS Repository.
Abstract: Carbon-coated CaWO4 nano-crystalline phases have been synthesized by ambient temperature solution precipitation method, characterized by X-ray diffraction, SEM and thermogravimetry and their electrochemical properties were studied versus Li metal. Galvanostatic cycling at a current of 60 mA/g in the voltage range 0.005-3.0 V on the 5 wt.% C-coated CaWO4 gave a reversible capacity of 230 ± 5 mAh/g corresponding to 2.5 mol of Li, which is almost stable from 20 to 50 cycles. Under the same conditions, the 10 wt.% C-coated CaWO4 showed a capacity of 355 ± 5 mAh/g (3.8 mol of Li) during the initial cycles, but the capacity degraded at a rate of 1.6 mAh/g per cycle in the range 5-100 cycles. A good operating voltage range was found to be 0.005-3.0 V with average discharge and charge potentials being 0.6 and 1.3 V, respectively. Coulombic efficiency in all cases was 96-98%. Cyclic voltammograms compliment the galvanostatic results. Impedance spectral data on the 10 wt.% C-coated CaWO4 at different voltages during the first and 20th discharge-charge cycle have been interpreted in terms of the variations in the bulk and charge-transfer resistances of the composite electrode. A reaction mechanism involving the formation/decomposition of the oxide bronze, 'LixWOy' has been proposed to explain the electrochemical cycling. © 2005 Published by Elsevier Ltd.
Source Title: Electrochimica Acta
ISSN: 00134686
DOI: 10.1016/j.electacta.2005.03.007
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