The thermodynamic and kinetic properties of silver intercalated niobium disulfide

Abstract

A study of structures, thermodynamic and kinetic properties of Ag intercalated 2H-NbS 2 is reported. The observed phases Ag xNbS 2, being a dilute gasphase (x<0.22) and a second- and first-stage phase (0.22≦×≦0.30 and 0.55 ≦×≦0.76 respectively) are structurally related. Silver atoms reside in tetrahedral holes between neighbouring sandwiches of NbS 2. Kinetic parameters of the mobile species (Ag) were obtained from ac response and the Galvanostatic Intermittent current Titration Technique (GITT), using samples of Ag xNbS 2 as solid solution electrode in an AgI electrochemical cell above 425 K. Both first- and second-stage Ag xNbS 2 exhibit fast ionic conduction. The relatively low chemical diffusion coefficient at 450 K, D̃ ≈ 10 −6.5 cm 2s −1, in the second-stage phase, as compared to that in the first-stage, D̃≈ 10 −4.5 cm 2s −1, is attributed to the coupling of the diffusion kinetics with stage conversion in islands type domains.