Interrelation between structural and electrochemical properties of the cathode based on vanadium oxide for rechargeable batteries

An electrochemical method for the anodic synthesis of active electrode materials based on vanadium oxides (electrochemically synthesized vanadium oxides - ESVO) in an aqueous vanadyl sulfate solution, has been evaluated with the main goal of optimizing the electrochemical performance of these materials as cathodes in lithium batteries. The influence of synthesis conditions and the regime of the subsequent thermal treatment of the vanadium oxide on its structural characteristics and electrochemical performance in non-aqueous electrolyte systems have been investigated. The study included the use of EC, DMC/LiPF₆ and PC, DME/LiClO₄ electrolyte solutions with two types of electrodes: (a) a vanadium oxide film deposited directly on a conducting substrate (stainless steel grid) by electrolytic synthesis, and (b) a composite electrode consisting of vanadium oxide, graphite or carbon black additives and a binder. The results of potentiodynamic and galvanostatic investigations obtained with these electrodes during cycling were highly reproducible, indicating good reversibility of the electrodes. Correlation between structural characteristics of the ESVO electrodes, their electrochemical responses and the evolution of the chemical diffusion coefficient of Li-ion with the state-of-discharge has been established and discussed.