Current-Dependent Growth Mechanisms of Sodium Metal Anode in Diglyme-Based Electrolytes
Sodium-ion batteries are economical substitute for lithium-ion batteries due to the earth abundance of sodium element [1, 2] . Similar to lithium metal anodes, while sodium metal anodes hold the promise to improve the energy density of next-generation sodium-ion batteries, the nonuniform electrodepo...
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Veröffentlicht in: | Meeting abstracts (Electrochemical Society) 2019-05, Vol.MA2019-01 (2), p.145-145 |
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Sprache: | eng |
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Zusammenfassung: | Sodium-ion batteries are economical substitute for lithium-ion batteries due to the earth abundance of sodium element
[1, 2]
. Similar to lithium metal anodes, while sodium metal anodes hold the promise to improve the energy density of next-generation sodium-ion batteries, the nonuniform electrodeposition of sodium metal that can lead to internal shorts remains a major obstacle toward its practical applications
[3]
. Here, we systematically investigated the electrodeposition of sodium in diglyme-based electrolytes in our unique capillary cells and realistic split cells. While a similar transition of electrodeposition mode to dendritic growth at Sand’s time was observed for sodium
[4]
, only the smooth surface growths were observed at under-limiting current densities, suggesting a possible much higher cycling efficiency due to much less surface areas to be covered by the solid electrolyte interphase (SEI) layers. By examining the limiting current and Sand’s time obtained from
operando
experiments with the capillary cells, the diffusion coefficient (1.13×10
-6
cm
2
s
-1
) and transference number (0.45) of sodium ions in 1M NaClO
4
in diglyme were accurately extracted, which were further verified by post-mortem analyses of linear sweep voltammetry experiments with split cells. The unique two current plateaus, shown in Figure 1, surprisingly can be explained by a single limiting current density in a self-consistent manner. At such plateaus, deposits of sodium metal were discovered to grow along the surface, rather than through the pores, of the ceramic-coated separator and form equiaxed and columnar dendrites with orthogonal branches similar to that found in solidification
[5]
.Our work provides a platform to not only evaluate the current-dependent growth mechanisms of sodium, but also reveal the roles of separators toward designing safe sodium metal batteries.
References
[1] D. Larcher and J. M. Tarascon. Towards greener and more sustainable batteries for electrical energy storage. Nature Chemistry. 2015; 7(1): 19-29.
[2] M. D. Slater, D. Kim, E. Lee and C. S. Johnson. Sodium-Ion Batteries. Advanced Functional Materials. 2013; 23(8): 947-958.
[3] C. L. Zhao, Y. X. Lu, J. M. Yue, D. Pan, Y. R. Qi, Y. S. Hu, et al. Advanced Na metal anodes. Journal of Energy Chemistry. 2018; 27(6): 1584-1596.
[4] P. Bai, J. Li, F. R. Brushett and M. Z. Bazant. Transition of lithium growth mechanisms in liquid electrolytes. Energy & Environmental Science. 2016; 9(10): 3221-3229. |
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ISSN: | 2151-2043 2151-2035 |
DOI: | 10.1149/MA2019-01/2/145 |