SPS driven lithium differential diffusion in NASICON-like structures

Abstract

Samples of nominal composition Li1.3Fe0.3Ti1.7(PO4)3 with a NASICON-type crystal structure, can be sintered up to 95% of the theoretical density at only 600 °C using spark plasma sintering, SPS. The final pellets however show different colouration in their upper and lower faces, being the upper face white and the lower one pink. The analysis of both surfaces by XPS shows a higher concentration of lithium on the white upper face, as a consequence of the polar diffusion of ions from the positive to the negative rams during SPS. On the other hand the study by XRD and SEM shows the formation of an extra phase in the upper face with nominal composition LiOPO4. A change in the cell parameters of the original NASICON structure is also observed, confirming the diffusion of lithium ions.

Keywords

• Batteries
• NASICON structure
• Spark plasma sintering
• Microstructure
• XPS