Poly(ionic liquid)-Based Quasi-Solid-State Copolymer Electrolytes for Dynamic-Reversible Adsorption of Lithium Polysulfides in Lithium–Sulfur Batteries

Abstract

The shuttle of the long-chain lithium polysulfides (LiPSs) is the main obstacle to the practical application of lithium–sulfur batteries. Herein, a poly­(butyl acrylate/1-ethyl-3-vinylimidazole bis­[(trifluoromethyl)­sulfonyl]­imide)-based quasi-solid-state copolymer electrolyte poly­(ethylene glycol) diacrylate (PEGDA-P­(BA-co-[EVIm]­TFSI) QPE-IL) was prepared for lithium–sulfur batteries. The butyl acrylate component with abundant ester groups ensures the strong chemical capture for LiPSs. What is more, the introduction of ionic liquid ([EVIm]­TFSI) can greatly improve the ionic conductivity and lithium-ion migration rate. More importantly, the dynamic-reversible adsorption of LiPSs was realized by chemical adsorption of ester-rich groups and electrostatic repulsion of free-moving negatively charged ions. As a result, the lithium–sulfur battery assembled by a reduced graphene oxide/carbon nanotube film@sulfur (rGOCTF@S) self-supporting cathode and QPE-IL displayed a high initial discharge capacity of 1179 mA h g–1, good cycling stability (72% capacity retention after 200 cycles at 0.5 C), and superior rate performance.

Ion transport and relaxation in phosphonium poly(ionic liquid) homo‐ and co‐polymers

“…More recently, Zhang and co-workers 62 demonstrated an alternating strategy to obtain solid polymer electrolytes having high mechanical strength, high ionic conductivity, high electrochemical stability and less Li dendrites growth by blending of copolymer based PIL (PPaB-MT) and P(VdF-HFP) containing 20% LiTFSI salt for Li-ion batteries. Cai and co-workers 74 4 that PIL and PIL based random copolymers reported in present work showed good thermal stability, less moisture sensitivity and good ionic conductivity and that fundamental view ensures the potential use of these materials as polymer electrolytes in energy storage devices.…”

“…More recently, Zhang and co‐workers 62 demonstrated an alternating strategy to obtain solid polymer electrolytes having high mechanical strength, high ionic conductivity, high electrochemical stability and less Li dendrites growth by blending of copolymer based PIL (PPaB‐MT) and P(VdF‐HFP) containing 20% LiTFSI salt for Li‐ion batteries. Cai and co‐workers 74 also synthesized PIL based quasi‐solid‐state copolymers (PEGDA‐P(BA‐co‐[EVIm]TFSI) QPE‐IL) for lithium‐sulfur batteries. Safa and coworkers 75,76 also synthesized a PIL (PDADMATFSI) based composite gel polymer electrolytes (PIL‐EMIMTFSI‐1 M LiTFSI) for lithium metal batteries (LMB).…”

Enhanced Cycling Performance of All‐Solid‐State Li‐S Battery Enabled by PVP‐Blended PEO‐Based Double‐Layer Electrolyte

“…It originated from the strong dipole–dipole interaction between LiPSs and electron‐rich donors in PVP. As a result, it caused red shifts in the C=O vibration, and the shift distance of C=O peak represents the strength of binding with LiPSs [54] . As can be seen, the stretching vibration peak of C=O red‐shifted from 1667 cm −1 to 1639 cm −1 .…”

“…As a result, it caused red shifts in the C=O vibration, and the shift distance of C=O peak represents the strength of binding with LiPSs. [54] As can be seen, the stretching vibration peak of C=O red-shifted from 1667 cm À 1 to 1639 cm À 1 . It proved that the strong interaction existed between the amide groups and LiPSs.…”

High ionic conduction, toughness and self-healing poly(ionic liquid)-based electrolytes enabled by synergy between flexible units and counteranions

“…Most recently, Cai and coworkers have prepared a PIL-based quasi-solid state copolymer electrolyte for lithium–sulfur batteries by polymerization of butyl acrylate (BA) with IL monomer and crosslinked with poly(ethylene glycol)diacrylate. 31 The main objective of such copolymer electrolyte system is to use abundant ester groups of the BA component to capture lithium polysulfides for improving the initial discharge capacity, cycle stability and rate performance of the assembled battery. However, the PIL-based copolymer chains may exhibit deficient movability due to covalently crosslinked networks.…”