• Journal of the Korean Electrochemical Society
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• v.5 no.1
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• pp.1-6
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• 2002

Silver doped vanadium pentoxides with a doping ratio Ag/V ranging from 0.03 to 0.11 were synthesized by sol-gel process, and $Li/Ag_xV_2O_5$ cell was investigated by the electrochemical methods. It appears to be amorphous layered material and entangled fibrous textures has been grown to form anisotropic corrugated fibrils. NMR measurements revealed that several different kinds of $Li^+$ ions exist in the lithium intercalated xerogel electrodes and the average cell potential was about 3.0V vs. $Li/Li^+$. The cell capacity of the silver doped $Ag_xV_2O_5$ xerogel cathodes was more than 359 mAh/g at discharge current 10mA/g and cycle efficiency $94\%$ was achieved.

• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.107-111
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• 2005

We have performed a study on the electrochemical characteristics and nuclear ($^7Li$) magnetic resonance of $V_2O_5$ xerogels that have been synthesized by the sol-gel reaction of $V_2O_5$ powder with hydrogen peroxide. NMR measurements revealed that chemical shift of $Li^+$ ions varied as lithium ions were inserted into $V_2O_5$ xerogel and that several different sites for $Li^+$ ions existed in the $V_2O_5$ xerogel structure. The electrochemical properties of the xerogel electrodes did not depend much upon the concentration of $V_2O_5$ and HCl that were used for the synthesis of $V_2O_5$ gels. The specific capacity of $V_2O_5$ xerogels were about 140 mAh/g, similar to that of the xerogels prepared by the ion exchange method.

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.491-495
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• 2005

Vanadium pentoxide xerogels with a doping ratio of $Al/V_2O_5$ ranging from 0.01 to 0.05 were synthesized by doping Al into $V_2O_5$ xerogel via the sol-gel process. By using the synthesized $Al_xV_2O_5$, the $Li/Al_xV_2O_5$ cells were assembled to investigate the chemical and electrochemical properties. Surface morphology of the $Al_xV_2O_5$ xerogel showed an anisotropic corrugated sheet-like matrix, and the interlayer distance was about $11.5{\AA}$. The IR spectra of the $Al_xV_2O_5$ revealed that the doped Al was coordinated to the vanadyl group in $V_2O_5$. The $Al_xV_2O_5$ xerogels showed enhanced reversibility and energy density compared with the $V_2O_5$ xerogel. The specific capacity of the $Al_{0.05}V_2O_5$ xerogel was more than 200 mAh/g at 10 mA/g discharge rate, and cycle efficiency was about 90% after the 31st cycling test between 1.9 V and 3.9 V.