Mixed Transition Metal Titanate and Vanadate Negative Electrode Materials for Na-Ion Batteries (Preprint)

Abstract

Sodium-ion batteries have the potential to be a low cost, sustainable replacement for lithium-ion batteries in large scale energy storage. The lack of practical negative electrode materials limit the development of Na-ion batteries. In this study, mixed transition metal titanates and vanadates were synthesized and electrochemically characterized in Na cells as well as Li cells for comparison. Some of these materials were found to have volumetric capacities that far exceeded that of Li in graphite. CoV3O8, CoTiO3 and Ca5Co4(VO4)6 were found to have sodiation mechanisms that were not simple conversion reactions. CoTiO3 in particular had low hysteresis and good reversibility, which is suggestive of an intercalation mechanism.