Designing a Safe Electrolyte Enabling Long‐Life Li/S Batteries

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.

Recent Advances of Two‐Dimensional (2 D) MXenes and Phosphorene for High‐Performance Rechargeable Batteries

“…Li–S batteries have attracted extensive attention in recent years because of their low cost, high theoretical specific capacity (1672 mAh g −1 ) and high energy density (2567 Wh kg −1 ) . Nevertheless, the low electrical conductivity of sulfur and fast capacity degradation resulting from polysulfide dissolution in the electrolyte limit the practical application of Li–S batteries .…”

Elucidating Interfacial Phenomena between Solid-State Electrolytes and the Sulfur-Cathode of Lithium–Sulfur Batteries

“…For instance, the use of organic-based liquid electrolytes raises concerns because of their flammability, formation of lithium dendrites, and low stability against the Li-metal anode. 6,7 In addition, long-chain polysulfides, formed at the cathode, are soluble in the liquid electrolyte and can result in the formation of an insulating layer because of parasitic reactions at the anode. 8,9 As a potential solution to solve these issues, solidstate electrolytes (SSEs) have recently been considered as an alternative for electrolyte systems.…”

“…In this search, one of the most promising chemistries is the lithium–sulfur (Li–S) battery because of its reduced cost, low toxicity, and high theoretical energy density (2567 W h kg –1 ). , However, there are some challenges that still need to be overcome before this technology is widely commercialized. For instance, the use of organic-based liquid electrolytes raises concerns because of their flammability, formation of lithium dendrites, and low stability against the Li-metal anode. , In addition, long-chain polysulfides, formed at the cathode, are soluble in the liquid electrolyte and can result in the formation of an insulating layer because of parasitic reactions at the anode. , As a potential solution to solve these issues, solid-state electrolytes (SSEs) have recently been considered as an alternative for electrolyte systems. , …”

A Combined Lithium Intercalation and Plating Mechanism Using Conductive Carbon‐Fiber Electrodes

“…The pores of the carbon fiber network are now filled up with electronically isolated Li deposits and (likely to be) excess SEI buildup, making the fibers undistinguishable. The sudden drop of the Li plating/stripping regime efficiency is likely caused by the combined effect of the gradual build‐up of residue Li and the continuous consumption of LiNO 3 [23,24,64] . These deteriorations occur sooner when the lithiation capacity and/or current density is higher.…”