The thermodynamics and kinetics of the gamma-lithium vanadium bronze structure

The reaction of lithium with alkali metal vanadium bronzes has been studied recently by several investigators, as these materials are of interest as possible positive electrode constitutents in both solid state and molten salt electrolyte secondary lithium batteries. There are several different structures in both the pure lithium vanadium bronzes and mixed alkali bronzes, and lithium insertion and deletion has been found to occur in them, in some cases at high rates and over appreciable ranges of composition. These materials also typically have low lithium activities, and thus high voltages compared to lithium. Its layer-like atomic arrangement and high voltages versus lithium make the gamma phase structure an especially attractive electrode reactant for use in lithium systems. Electrochemical methods have been employed to determine the equilibrium potential-composition relations, and data are reported on the equilibrium electrochemical titration curve. In addition, the chemical diffusion coefficient has been measured by the galvanostatic transient technique. These kinetic parameters are similar to those previously found in materials with the beta structure.