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Investigation of the Solid Electrolyte Interphase (SEI) in Polysulfide-Containing Glyme-Based Electrolytes

Tuesday, 31 May 2016
Exhibit Hall H (San Diego Convention Center)
M. Agostini (Rome University), X. Shizhao (National University of DefenseTechnology, China.), A. Matic (Chalmers University of Technology), and J. Hassoun (University of Ferrara, Italy)
The massive employment of non-renewable fossil fuels has resulted in a rapid increase of greenhouse gas emission and global warming. The consequent excessive climate changes have triggered a new energy policy, mainly focused on clean and renewable sources.1 Solar and wind energy conversion systems are the most suitable for large-scale diffusion, in particular in view of recent advances reflecting in cost reduction and economic advantages.1 However, these discontinuous energy sources require side systems for energy storage and electrical grid stabilization.2 Furthermore, electrified vehicles using high-energy storage systems matching the automotive market requirements may effectively mitigate the environmental pollution in large urban areas.2 Thus, there is a large push for the development of high capacity energy storage technologies.

Lithium−sulfur battery appears as one of the most promising technologies due to its high theoretical capacity and energy density, i.e. 1672 mAh g−1 and 3500 Wh kg−1 basing on the sulfur weight, respectively, the natural abundance, the low toxicity of elemental sulfur, and the expected low cost.3 However, a sulfur electrode in a lithium battery shows several drawbacks, including poor electronic conductivity, high solubility of the polysulfides formed during the electrochemical process, large volume changes (approximately 80%) by operation, and precipitation of insoluble Li−S intermediates formed during the discharge process in the electrolyte solution. These remarkable issues, leading to severe capacity fading and Li−S cell deterioration upon cycling, have been already investigated in terms of the reaction mechanism.4

Herein, we reported a detailed study of an important aspect, i.e., the chemical−physical and electrochemical characterization of the electrode−electrolyte interphase. Indeed, we comparatively investigate the properties of the SEI film formed at the lithium electrode surface in tetraethylene glycol dimethyl ether (TEGDME)-based electrolytes containing different polysulfide species, namely Li2S2, Li2S4, Li2S6, and Li2S8, added within a constant concentration of 5% w/w.5

References

(1) Armand, M.; Tarascon, J.-M. Nature 2008, 451, 652−657.

(2) Bruce, P. G.; Freunberger, S. A.; Hardwick, L. J.; Tarascon, J.-M. Nat. Mater. 2012, 11, 19−29.

(3) Ji, X.; Nazar, L. F. J. Mater. Chem. 2010, 20, 9821−9826.

(4) Ryu, H.-S.; Guo, Z.; Ahn, H.-J.; Cho, G.-B.; Liu, H. J. Power Sources 2009, 189, 1179−1183.

(5) Agostini, M.; Shizhao, X.; Matic, A.; Hassoun, J. Chem. Mater 2015, 27, 4604−4611.