A THERMODYNAMIC AND KINETIC-STUDY OF ELECTROCHEMICAL LITHIUM INTERCALATION IN NA0.33V2O5 BRONZE PREPARED BY A SOL-GEL PROCESS

Thermodynamic and kinetic investigations on the electrochemical lithium intercalation into β Na0.33V2O5 synthesized by a sol-gel process (SGP) have been found to correlate well with the scheme suggested for the filling of the available sites M of the p structure by Li+ ions. Indeed, the whole of the thermodynamic, kinetic, and crystallographic data have enabled one to explain the electrochemical behavior exhibited by the SGP bronze Na0.33V2O5 in a lithium ion containing nonaqueous solvent. The partial molar quantities [formula omitted],[formula omitted], and [formula omitted] were obtained from EMF-temperature measurements and coulometric titration curves. Two main ordering processes were seen to take place in the composition range 0 < x < 0.3 and 0.3 < x < 0.7 in LixNa0.33V2O5. The chemical diffusion coefficient of lithium was found to be proportional to the number of the vacant sites; [formula omitted] varies from 10−9 up to 10−12 cm2 s−1 for 0 < x < 0.7 and is in the order 10−14 for higher Li contents. Finally, the better electrochemical behavior of the SGP bronze β Na0.33V2O5, as compared with that exhibited by the similar bronze obtained through solid-state reactions at 700°C highlighted the advantage of the sol-gel technique for the synthesis of new cathodic intercalation materials usable in secondary lithium cells. © 1990, The Electrochemical Society, Inc. All rights reserved.