Sodium-ion diffusion and ordering in single-crystal P2 -Nax CoO2
Journal
Physical Review B - Condensed Matter and Materials Physics
Journal Volume
78
Journal Issue
5
Date Issued
2008
Author(s)
Shu, G. J.
Abstract
Sodium-ion self-diffusion in P2 (γ) -Nax CoO2 has been studied using a single crystal as an electrode. Mass transport and thermodynamic properties of Na ions were measured by the potentiostatic intermittent titration technique on a single-crystal electrode with greater accuracy under well-defined diffusion geometry. Excluding the significantly slower diffusion behavior near particular Na ordered phases, average diffusion coefficients DNa are extracted to be 1.2±0.5× 10-7 cm2 /s for x>0.5 and 4.1±0.5× 10-8 cm2 /s for x<0.5, respectively. The existence of stable phases with special Na ordering of x∼0.25, 0.33, 0.43, 0.5, 0.55, and 0.71 are verified by either the maximum or diverging signature of the x -dependent self-diffusion coefficients. © 2008 The American Physical Society.
Type
journal article