Structure stability of Li x H y V 3 O 8 exposed to water-vapour
Courtesy of Inderscience Publishers
Chemically lithiated Li
was prepared as the starting material in this study owing to its interesting properties for lithium-ion intercalation and further application in the positive electrode of lithium-ion batteries. The hydrophilic character of the synthesised compound was evaluated because even ppm water level inside batteries containing electrolytes with fluorinated salts like LiPF
can dramatically influence the battery stability. The structural stability of the lithiated vanadate after exposure to water-vapour was evaluated ex situ by XRD, TGA and TEM. TGA showed that at least 4 wt.% of water can be incorporated into the material. Water intercalates in the vanadate lattice filling the particles from the outer shell towards the bulk. Prolonged exposure to water-vapour saturated atmosphere leads to irreversible exfoliation of the crystal structure. Weakly bonded intercalated water can be removed without any damage to the crystal structure by an annealing step at 200ºC for 2 h in air.
Keywords: lithium-ion battery, cathode, H 2 V 3 O 8, high energy density, hydrophilic, intercalation, exfoliation, hydrothermal.