Self-Diffusion in Bulk Lithium and Sodium and Its Impact on the Whisker Growth during Electrodeposition

AV Sergeev and YO Kondratyeva and KO Borodin and LV Yashina, JOURNAL OF THE ELECTROCHEMICAL SOCIETY, 171, 120508 (2024).

DOI: 10.1149/1945-7111/ad9991

Here we propose computational insight into mass transport in bulk polycrystalline lithium and sodium in relation to the whisker growth problem. Different mechanisms of self-diffusion were evaluated at both atomistic and macroscopic levels based on the results of the molecular dynamics simulations. It was found that in sodium the vacancy mechanism of self-diffusion prevails due to abundance of this type of defects. In contrast, in lithium, vacancy diffusion makes a smaller contribution than the interstitials diffusion, while the mass transfer along the grain boundaries is predicted to have major impact. Overall self- diffusion in sodium is approximately three orders of magnitude faster than in lithium. Therefore, a reasonable approach to solving the lithium whisker problem would be to promote the self-diffusion, particularly by reducing the average grain size. For sodium mass transport seems to be not so critical factor.

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