Stability and Semiconducting Behavior of Magnesium Polysulfides by Nonequivalent sp3 Hybridizations

Guang Zhang; Kai Wang; Qiaoyu Liu; Mingyuan Pan; Ding Shen; Yansun Yao; Lailei Wu; Huiyang Gou

doi:10.1021/acs.inorgchem.3c02398

Stability and Semiconducting Behavior of Magnesium Polysulfides by Nonequivalent sp³ Hybridizations

Inorg Chem. 2023 Sep 18;62(37):15226-15233. doi: 10.1021/acs.inorgchem.3c02398. Epub 2023 Sep 6.

Authors

Guang Zhang¹, Kai Wang¹, Qiaoyu Liu^{2

3}, Mingyuan Pan², Ding Shen¹, Yansun Yao⁴, Lailei Wu^{1

2}, Huiyang Gou³

Affiliations

¹ College of Material Science and Engineering, Liaoning Technical University, Fuxin 123000, China.
² State Key Laboratory of Metastable Materials Science and Technology, College of Material Science and Engineering, Yanshan University, Qinhuangdao 066004, China.
³ Center for High Pressure Science and Technology Advanced Research, Beijing 100193, China.
⁴ Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N5E2, Canada.

PMID: 37672326
DOI: 10.1021/acs.inorgchem.3c02398

Abstract

The Mg/S battery has attracted enormous interest in recent years due to its high theoretical capacity, low cost, and high security. However, the understanding of many intermediate magnesium polysulfides in the Mg/S battery remains elusive. Combining extensive structural search and first-principles calculations, we investigate the phase stability, structural character, and electronic structure of magnesium polysulfides in a wide range from MgS to MgS₈. The pyrite-type MgS₂ (space group: Pa3̅) is predicted to be stable. Five magnesium polysulfides, MgS_x (x = 3, 4, 5, 6, and 8), are found to be metastable, with formation enthalpies slightly above the convex hull. S₂ dimer, "V"-like S₃, and highly distorted S_x chains are found for the polysulfides with bond lengths close to or slightly longer than S₈ and bond angles similar to S₈. A wide range of band gaps (0.77-2.82 eV) are revealed for the polysulfides due to the contribution of the nonequivalent sp³ hybridization of the S atoms in S_x^2-. Our results can help to further understand the electrochemical process in the Mg/S battery.