Journal
JOURNAL OF POWER SOURCES
Volume 280, Issue -, Pages 695-702Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jpowsour.2015.01.093
Keywords
Electrochemistry; DFT calculations; Li/Na-ion battery
Ask authors/readers for more resources
Recently, different and unexpected electrochemical behaviours have been demonstrated for MxSb electrodes (M = Li, Na) in Li/Na ion batteries. Despite a similar thermodynamic stability of the hexagonal and cubic polymorphs of Li3Sb, mostly cubic Li3Sb is observed at the end of discharge. In contrast, mostly the hexagonal Na3Sb polymorph is observed when cycling the Na/Sb, in agreement with its higher thermodynamic stability compared to the cubic polymorph. This polymorph selectivity is here investigated by means of simple thermodynamic and electrostatic considerations using first-principles Density Functional Theory (DFT) calculations. We show that the Na-based polymorphs are more ionic than their Li-based homologues, despite less ionic Na/Sb interactions. We establish a direct correlation between the relative compactness and stability of the M3Sb polymorphs to rationalize the preference of the hexagonal structure type for the most ionic compounds of the M3Sb series (M = Li, Na, K, Rb, Cs). The M-Sb interactions are further linked to the different electrochemical behaviours of the MxSb electrodes through Madelung constant calculations. This method is based on the knowledge of only one given MxSb composition and thus allows rationalizing the different intermediate compositions achieved through electrochemical cycling. To validate our method, we finally provide the first-principles computed phase stability diagrams which further reveal two new phases for both Li-Sb and Na-Sb systems. (C) 2015 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available