title: Formation of Zintl Ions and Their Configurational Change during Sodiation in Na-Sn Battery.
abstract: Despite their large theoretical storage capability, Na-Sn batteries exhibit poor round-trip energy efficiencies as compared to Li-Si batteries. Here, we report the results of a comprehensive study to elucidate how and why Na-Sn batteries exhibit such a low energy efficiency. As a convincing evidence for this behavior, we observed that the resistivity of the Sn anode increased by 8 orders of magnitude during in situ sodiation experiments, which is attributed to the formation of electrically resistive Zintl ions in the sodiated Sn. Continual sodiation induced the development of residual stresses at the Sn anode and caused the distortion of Zintl ions from their ideal configuration. This distortion caused a change in the electronic structure, resulting in the increased resistivity of the sodiated Sn. Our findings offer some solutions that can be used to improve the energy efficiency of Na-Sn batteries.
authors.affiliation: Department of Materials Science and Engineering, Korea University , Seoul 136-701, Republic of Korea.
authors.forename: Yong-Seok
authors.initials: YS
authors.lastname: Choi
authors.affiliation: Department of Materials Science and Engineering, Korea University , Seoul 136-701, Republic of Korea.
authors.forename: Young-Woon
authors.identifier: 0000-0003-2684-7720
authors.initials: YW
authors.lastname: Byeon
authors.affiliation: Advanced Analysis Center, Korea Institute of Science and Technology , Seoul 136-791, Republic of Korea.
authors.forename: Jae-Pyoung
authors.initials: JP
authors.lastname: Ahn
authors.affiliation: Department of Materials Science and Engineering, Korea University , Seoul 136-701, Republic of Korea.
authors.forename: Jae-Chul
authors.identifier: 0000-0002-9294-2163
authors.initials: JC
authors.lastname: Lee
keywords: FEM; Na-ion battery; Zintl ion; ab initio simulation; in situ sodiation experiment; resistivity