Thermodynamics and cell chemistry of room temperature sodium/sulfur cells with liquid and liquid/solid electrolyte

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• 作者：Sebastian Wenzel ; Hauke Metelmann ; Christine Rai? ; Anna Katharina D¨¹rr ; J¨¹rgen Janek ; Philipp Adelhelm
• 关键词：Beta alumina ; Sodium batteries ; Sodium electrochemistry ; Sodium&ndash ; sulfur cell
• 刊名：Journal of Power Sources
• 出版年：2013
• 出版时间：1 December, 2013
• 年：2013
• 卷：243
• 期：Complete
• 页码：758-765
• 全文大小：1972 K

文摘

The cell chemistry of sodium/sulfur cells operating at room temperature (RT-Na/S cells) is being studied electrochemically and structurally. We show by means of X-ray photoelectron spectroscopy that the cell reaction is incomplete but prove that the end members of the cell reaction (S and Na₂S) form among the expected polysulfide species Na₂S_x. The sulfur utilization can be improved by employing a solid electrolyte membrane (beta¡å-alumina) that prevents the diffusion of the soluble polysulfide species toward the sodium side. As an important finding, the Na⁺ conduction within the solid electrolyte phase and across the two liquid/solid interfaces results in only small overpotentials. Nevertheless the utilization of sulfur in the present RT-Na/S (475?mAh?g^?1) cells is lower than the theoretical value (1675?mAh?g^?1). One probable reason is the chemical instability of the widely used PVDF binder. Also, the thermodynamic properties of RT-Na/S cells operating at room temperature are discussed and compared with the currently much more studied RT-Li/S cells.