Advanced lithium batteries for implantable medical devices: Mechanistic study of SVO cathode synthesis

Silver vanadium oxide (SVO, Ag₂V₄O₁₁) was synthesized in solid-state reactions from silver carbonate and silver metal powder starting materials with vanadium oxide (V₂O₅) as the vanadium source. These powders were prepared as primary cathode materials for lithium batteries. Thermal analyses of stoichiometric mixtures of V₂O₅ and silver sources were used to elucidate the mechanism of Ag₂V₄O₁₁ formation. V₂O₅ reacts with Ag₂CO₃ in a two step decomposition/combination (DC) reaction. Weight gain measured by TGA during the reaction of Ag(0) + V₂O₅ in O₂ indicated the formation of Ag₂V₄O₁₁. XRD analysis of the synthesis products of the Ag(0) + V₂O₅ reaction indicated the formation of AgV₂O₅ under inert atmosphere and Ag₂V₄O₁₁ under oxidizing (air or O₂) conditions. The surface area and morphology of the materials were strongly influenced by the synthesis method, linked to the parameters of time, temperature, and reaction atmosphere. The electrochemical performance of the SVO cathode material also depended on the synthesis method, where SVO prepared from the DC reaction mechanism yielded improved long-term performance.