First‐Principles Study of Na‐Ion Battery Performance and Reaction Mechanism of Tin Sulfide as Negative Electrode. Issue 4 (1st April 2019)

• Record Type: Journal Article
• Authors: Kotaka, Hiroki; Momida, Hiroyoshi; Kitajou, Ayuko; Okada, Shigeto; Oguchi, Tamio
• Is Part Of: Chemical record. Volume 19:Issue 4(2019)
• Page Start: 811
• Page End: 816
• Publication Date: 2019-04-01
• Subjects: Na-ion battery -- Negative electrode -- First-principles calculation -- Battery performance -- X-ray absorption spectrum; Chemistry -- Periodicals; 540
• DOI: 10.1002/tcr.201800167
• Languages: English
• ISSNs: 1527-8999

Abstract

Abstract: We study the Na‐ion battery characteristics of SnS as a negative electrode by first‐principles calculations. From energy analyses, we clarify the discharge reaction process of the Na/SnS half‐cell system. We show a phase diagram of Na−Sn−S ternary systems by constructing convex‐hull curves, and show a possible reaction route considering intermediate products in discharge reactions. Voltage‐capacity curves are calculated based on the Na−SnS reaction path that is obtained from the ternary phase diagram. It is found that the conversion reactions and subsequently the alloying reactions proceed in the SnS electrode, contributing to its high capacity compared with the metallic Sn electrode, in which only the alloying reactions progresses stepwise. To verify the calculated reaction process, x‐ray absorption spectra (XAS) are calculated and compared with experimental XAS at S K ‐edge, showing meaningful XAS changes associated with Na2 S and SnS in discharged and charged states, respectively. Abstract : By using the first‐principles calculations, we investigate discharge reaction mechanisms in a negative electrode of tin sulfide SnS for sodium‐ion batteries. Possible reaction formulae in Na/SnS during the discharge processes are theoretically shown based on the ternary Na−Sn−S phase diagrams. Theoretical voltage‐capacity curves and x‐ray absorption spectra show reasonable agreements with experiments.