Solvent Effects on Intercalation Reactions in VOPO₄·2H₂O

Jiahui Liu and Daniel R. Talham

University of Florida

Vanadium phosphate dihydrate, VOPO₄·2H₂O, has been investigated as a cathode material for lithium-ion batteries due to its high specific capacity and good cycling stability. Batteries rely on intercalation reactions, and while solvent effects during intercalation reactions are well documented, their origins are not well understood. This study explores ferrocene intercalation in VOPO₄·2H₂O to investigate the origins of solvent effects. Studying intercalation in several solvents, different processes are revealed, including preintercalation, and host dehydration in addition to ferrocene intercalation. Rates of intercalation have been compared. Intercalation products are shown as a mixture of stage 1 and stage 2 compounds and ratios of these two compounds also show dependence on solvents. The results are interpreted within the context of changes in surface energy induced by solvents.