Flexible Freestanding Thin Polyethylene Oxide‐Based Film as Artificial Solid–Electrolyte Interface to Protect Lithium Metal in Lithium–Sulfur Batteries

Abstract

Lithium–sulfur batteries (LSBs) that utilize sulfur and lithium (Li) metal as electrode materials are highly attractive for transportation applications due to their high theoretical gravimetric energy density. However, two major challenges currently impede the commercialization of LSB, which are the formation of Li dendrites and polysulfide shuttling. To mitigate these two effects, a protective film or artificial solid–electrolyte interface (SEI) can be applied directly to the Li‐metal surface. Herein, the preparation of freestanding polyethylene oxide (PEO)‐based films using tape casting as a scalable coating technique is presented. Moreover, the films are applied directly to the Li surface via a solvent‐free method. To demonstrate the suitability of the developed PEO‐based films, the long‐term cycling performance of the lithium–sulfur cells is discussed. It is shown that the cells with the Li‐metal surface protected by PEO‐based films achieve better stability and reproducibility, reaching ≈400 mA h g S−1 after 250 cycles compared to ≈200 mA h g S−1 after 250 cycles for the bare Li‐metal electrode. An extensive postmortem analysis of the Li‐metal electrode surface with scanning electron microscopy is additionally shown, revealing that the PEO‐based artificial SEIs form uniformly with a low level of defect layers at the interface with the Li‐metal electrode, which indicates the creation of a stable SEI.

Recent advances in li metal anode protection for high performance lithium-sulfur batteries

“…Research and development of organic-based artificial SEI layers are playing a crucial role in enhancing the performance and safety of LSBs [90,91,[97][98][99][100][101]. Various studies have demonstrated that organic-based SEI layers can enhance the stability of Li metal anodes, minimize side reactions, and prevent dendritic growth, thereby extending the battery's cycle life.…”

Effect of ether medium in LiTFSI and LiFSI‐based liquid electrolytes for lithium–sulfur batteries

“…Transportation of the Li anode from the dry room atmosphere (average dew point = −40°C to −45°C) to the SEM was conducted using a self-made SEM holder that opens in high vacuum. 20 The S cathodes were prepared in the same dry room onto usual SEM holders and put into a box which was then sealed under argon in an aluminum bag. To maintain a low exposure to the surrounding atmosphere, the S cathode samples were opened and quickly put into the SEM directly after the chamber was opened.…”

Electropolymerisation Technologies for Next-Generation Lithium–Sulphur Batteries

“…As a representative strategy, a protective layer is formed on the surface of Li, which should exhibit the following characteristics: chemical/electrochemical stability to electrolytes, high Li-ion diffusion rate, stability to LPSs, and flexible mechanical properties [38,[40][41][42][43]. However, even if an ideal protective layer exists, the uniform coating on the surface of Li for constructing a stable interface between the protective layer and Li remains an issue to be addressed.…”