Designing a Safe Electrolyte Enabling Long‐Life Li/S Batteries. Issue 18 (19th August 2019)

• Record Type: Journal Article
• Authors: Agostini, Marco; Sadd, Matthew; Xiong, Shizhao; Cavallo, Carmen; Heo, Jungwon; Ahn, Jou Hyeon; Matic, Aleksandar
• Is Part Of: ChemSusChem. Volume 12:Issue 18(2019)
• Page Start: 4176
• Page End: 4184
• Publication Date: 2019-08-19
• Subjects: batteries -- ionic liquids -- lithium -- sulfur -- electrolytes; Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.201901770
• Languages: English
• ISSNs: 1864-5631

Abstract

Abstract: Lithium–sulfur (Li/S) batteries suffer from "shuttle" reactions in which soluble polysulfide species continuously migrate to and from the Li metal anode. As a consequence, the loss of active material and reactions at the surface of Li limit the practical applications of Li/S batteries. LiNO3 has been proposed as an electrolyte additive to reduce the shuttle reactions by aiding the formation of a stable solid electrolyte interphase (SEI) at the Li metal, limiting polysulfide shuttling. However, LiNO3 is continuously consumed during cycling, especially at low current rates. Therefore, the Li/S battery cycle life is limited by the LiNO3 concentration in the electrolyte. In this work, an ionic liquid (IL) [ N ‐methyl‐( n ‐butyl)pyrrolidinium bis(trifluoromethylsulfonyl)imide] was used as an additive to enable longer cycle life of Li/S batteries. By tuning the IL concentration, an enhanced stability of the SEI and lower flammability of the solutions were demonstrated, that is, higher safety of the battery. The Li/S cell built with a high sulfur mass loading (4 mg cm −2 ) and containing the IL‐based electrolyte demonstrated a stable capacity of 600 mAh g −1 for more than double the number of cycles of a cell containing LiNO3 additive. Abstract : Live long and prosper : A new approach to mitigate the "shuttle" mechanism in Li/S batteries is developed by controlling the solubility/mobility of Li polysulfide by using a rationally designed electrolyte medium containing N ‐methyl‐( n ‐butyl)pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquid as an additive. The addition of the ionic liquid allows longer cycle performance and an improved interface stability in Li/S cells.